List of ecoregions in North America (CEC)

This list of ecoregions of North America provides an overview of North American ecoregions designated by the Commission for Environmental Cooperation (CEC) in its North American Environmental Atlas. It should not be confused with Wikipedia articles based on the classification system developed by the World Wildlife Fund, such as List of ecoregions (WWF) and Lists of ecoregions by country.

The commission was established in 1994 by the member states of Canada, Mexico, and the United States to address regional environmental concerns under the North American Agreement on Environmental Cooperation (NAAEC), the environmental side accord to the North American Free Trade Agreement (NAFTA). The Commission's 1997 report, Ecological Regions of North America, provides a framework that may be used by government agencies, non-governmental organizations, and academic researchers as a basis for risk analysis, resource management, and environmental study of the continent's ecosystems.[1] Ecoregions may be identified by similarities in geology, physiography, vegetation, climate soils, land use, wildlife distributions, and hydrology.

The classification system has four levels. Only the first three levels are shown on this list. "Level I" divides North America into 15 broad ecoregions. "Level II" subdivides the continent into 52 smaller ecoregions. "Level III" subdivides those regions again into 182 ecoregions.[1][2] "Level IV" is a further subdivision of Level III ecoregions. Level IV mapping is still underway but is complete across most of the United States. For an example of Level IV data, see List of ecoregions in Oregon and the associated articles.

Arctic Cordillera

Overview

The Arctic Cordillera is one of the world's fifteen diverse ecoregions, characterized by a vast mountain chain spanning the spine of the range. The geographic range is composed along the provinces of Labrador: including Eastern Baffin, The Devon Islands, Ellesmere, Bylot Islands, the Thorngat Mountains, and some parts of the Northeastern fringe. The landscape is dominated by massive polar icefields, alpine glaciers, inland fjords, and large bordering bodies of water, distinctive of many similar arctic regions in the world. Although the terrain is infamous for its unforgiving conditions, humans maintained an established population of 1000 people – 80% of which were Inuit. In addition, the landscape is 75% covered by ice or exposed bedrock, with a continuous permafrost that persists throughout the year, making plant and animal life somewhat scarce. The temperature of the Arctic Cordillera ranges from 6 °C in summer, down to –16 °C in winter.Vegetation is largely absent in this area due to permanent ice and snow.[3]

Natural resources and human influence

The Arctic Cordillera is a cold, harsh environment making plant life and animal-life sparse; even soil is rare in this ecoregion. Moss, cottongrass, and Arctic heather are examples of plant life that can be found in valleys. Meanwhile, polar bears, seals, and walruses roam the shores and survive off the thriving marine ecosystem.[4] Fish, clams, and shrimp are just a few of the resources the local Inuit communities of Nunavut use in the highly productive waters to support their economy. Nunavut’s government is also investing in exploration of mineral resources; Breakwater Resources, for example, is a zinc-lead mine in Arctic Bay that just reopened in April 2003 after closing the year before due to declining resources.[5] Climate change is the strongest human influence in the Arctic Cordillera. Rising temperatures in the Arctic are causing ice shelves, and the habitats they provide, to shrink from year to year. Researchers of global warming also express concern for the economic, political, and social consequences of the resulting decline in fisheries stocks expected because of the changing climate.[6]

Climate

The Arctic Cordillera is one of Canada’s most inhospitable climates. The northern part is covered by the ice caps and glaciers cover a large part of the south. It was not always as cold as it is today. 40 million-year-old tree stumps found in 1985 on Axel Heiberg Island suggest that the area used to be warmer and wetter with much more biodiversity. Today the weather is generally very cold and dry with a few weeks of sun and rain in the summer. Snow is the most common form of precipitation in the Cordillera. The region only gets 20−60 centimeters of precipitation annually. The temperature in this ecoregion averages around 4 degrees Celsius during the summer. In the winter the temperature is −35 degrees Celsius on average. A polar cell is a system of winds that influence the climate of the Cordillera. It is made up of the Westerlies, which are winds that blow warm air east to west from 30 to 60 degrees latitude up to the poles, and the Polar Easterlies, which blow cold air back south where it will repeat the process.[7]

Hydrology

This region can be divided up into three major areas Ellesmere Island, Baffin Island, and the coastline of the most northern part of Labrador. Nearly 75% of the land within this ecoregion is exposed bedrock or ice. The majority of the water in this ecoregion is locked up in frozen ice and snow, therefore there are very few named rivers or other bodies of water within this region. The annual amount precipitation is about 200 mm, which usually falls down as snow or ice. Huge ice caps dominate the landscape, and they spawn large glaciers that are pushed down steep fjords and into the sea. When the temperature gets above freezing for an extended period time a little amount of runoff is created, which is generally under 200 mm annually.[8]

Geology, topography and soil

The Arctic Cordillera is dominated by vast mountain ranges stretching for thousands of miles, virtually untouched by man. These mountains were formed millions of years ago during the mid-Mesozoic when the North American Plate moved northward, pushing earth and rock upwards. The mountains of the north contain metamorphic and igneous rock, and are predominantly sedimentary rock. On the other hand, the southern mountains are greater, composed of granite gneiss and magmatic volcanic rock. These mountains are characterized as being highly erodible with very steep and jagged cliffs with narrow ledges. The highest peak in the Arctic Cordillera mountain range is Barbeau Peak – standing almost nine thousand feet tall. In general, the Arctic Cordillera Mountain Range is most similar (in composition and age) to the Appalachian Mountain Range of the United States. However, as the Appalachian Mountains are slightly older, their cliffs have been eroded, and are less jagged than those of the Arctic Cordillera. This ecoregion is also home to very limited amounts of exposed soil. Only in extremely sheltered places – such as that of caves – is surface soil present. The remaining soil is hidden beneath deep snow and ice, and is kept in a constant state of permafrost.[9]

Plant communities

The Arctic Cordillera is a very high stress environment for plants to try and grow and regenerate. Vegetation is largely absent due to permanent ice and snow. Due to the extremely cold, dry climate, along with the ice-fields and lack of soil materials, the high and mid-elevations are largely devoid of significant populations of plants. In the warmer valleys at low elevations and along coastal margins, the plant cover is more extensive, consisting of herbaceous and shrub-type communities. Stream-banks and coastlines are the most biologically productive areas here. The plants in this region have a history of being survivors and stress tolerant to high winds, low temperatures, few available macronutrients like nitrogen and phosphorus. Plants have adaptations such as fluffy seed masses, staying low to the ground, and use of other plant masses for extra insulation.[10]

Keystone species

Due to the harsh environments and extremely low temperatures that encompass the Arctic Cordillera, there is not a large variety of plants and animals that are able to survive and exist as a population. However, some animal species, both herbivores and carnivores, are able to survive the extreme weather and terrain. Among these animals are wolves, polar bears, Arctic foxes, musk-oxen, and caribou. For the most part, the large carnivores are the dominant species in the ecoregion, mainly the polar bear. It is the keystone species for the area due to many of its habits, including its diet and hunting strategies. In addition, the life history of the 22,000 polar bears in the Arctic clearly defines its current existence in the Arctic Cordillera.[11]

The large carnivorous species defines the ecoregion due to its intimate relationship with the ice as well as its extremely intelligent hunting tactics.[12] No other predatory animal defines the Arctic Cordillera as well as the large white polar bear and that is why when people think about arctic animals, they think about the polar bear. As long as the polar bear remains existent, it will be the keystone species of the Arctic Cordillera. However, this existence relies solely on the degree of ice melt that is encountered in the future.[13]

Endangered species

Polar bear
Polar bear

The polar bear is one of the most notably affected species in the Arctic Cordillera, mainly due to their heavy reliance on arctic ice for hunting and bedding grounds. Habitat loss, caused by global warming, has led to many dangerous behavioral changes including a new behavior called long swims. These are swims lasting as long as ten days performed by mother bears to attempt to find food for their cubs, which generally lead to the death of the cub.[14] Because of their stature and aggressiveness, direct conservation practices are not very useful to the polar bear. Instead, scientific observation to better understand these animals is the largest form of traditional conservation.[15]

Arctic black spruce

The Arctic black spruce is an example of a plant native to the Arctic Cordillera that is considered to be in ecological decline. The black spruce is a species of least concern because of habitat loss and deforestation from the spruce budworm moth.[16] In the Arctic Cordillera however, the black spruce population is in good health, and is slowly gaining habitat through the retreat of polar ice.[17]

Bowhead whale
Bowhead whale

Another species that is of great importance to this ecoregion is the endangered Bowhead whale (Balaena mysticetus). Five total stocks of this species exist in the region within the arctic oceans and adjacent seas: the Spitsbergen stock, Baffin Bay/Davis Strait, stock and Hudson Bay/Foxe Basin Stock, Sea of Okhotsk Stock, and the Bering/Chukchi/Beaufort Stock. Historically, these whales have served as a cultural icon, and an important source of food and fuel to the Inuit people. At this point in time, their populations were estimated between 30,000 and 50,000 individuals.

However, with the expansion of commercial whaling in the 16th and 17th century, this species was exploited to dangerously low numbers. Commercial hunting of bowheads was officially ended in 1921, when moratoria were established to protect the remaining 3,000 individuals left in the wild.[18]

Today, those same moratoria are still in effect, but the Bowhead population has been reinstated to a manageable population of between 7,000 and 10,000 individuals. Nonetheless, these whales have been (and remain) on the IUCN Red List since 1984.[19] One of the most important conservation efforts for this species is “legal” protection by the International Convention for the Regulation of Whaling, which came into force in 1935. This convention was further strengthened and ratified by Canada in 1977 to support the International Whaling Commission’s (IWC) recommendation for full protection of the bowhead whale.[20] Further conservation efforts have involved more physically demanding solutions, including the recommended funding of specialized technical machines that have the capability to remove debris that commonly kills these whales due to entanglement and accidental indigestion.[19]

Tundra

The location of the tundra in North America is highlighted in light blue.

One of the planet's most recent biomes, a result of the last ice age only 10,000 years ago, the tundra contains unique flora and fauna formed during the last glaciation in areas unrestricted by permanent ice. The tundra region is found in high latitudes, primarily in Alaska, Canada, Russia, Greenland, Iceland, Scandinavia, as well as the Antarctic Islands. Consisting of the arctic, alpine and Antarctic regions, and stemming from the Samer language, tundra literally means a "high and dry place".

Plant communities

The adversity of soil and climatic conditions proves for low production levels, as well as little biomass accumulation due to slow rates of nutrient release in cold and wet soils, specifically as a result of limited nitrogen and phosphorus (Nadelhoffer et al. 1996) Additionally, there are low temperatures and strong winds in the tundra causing most vegetation to be dominated by woody plants that hug the soil. Within the tundra, some dominant plant species include lichen, cotton grass, and Arctic willow.

Lichens

Lichens dominate the tundra as the regions major primary producer. A symbiotic combination of algae and fungi, a lichen is able to survive in the harsh conditions of the tundra (Biodiversity Institute of Ontario et al. 2010). Their unique structure and survivability makes lichen a prominent and keystone plant species in the tundra ecosystem.

Cotton grass is another dominant plant species in the tundra producing much of its growth early in the summer. Being a member of the sedge family, it forms a large part of the vegetation in the tundra because it is able to deal with harsh and cold temperatures. This perennial plant contains flowering heads with dense brittles that are spread during heavy winds, enabling pollination (Wein and Bliss 1974). Additionally, its survivability in the tundra can be attributed to cotton grass’s ability to photosynthesize in low temperatures and low light.

The Arctic willow, commonly named rock willow, is found in the North American tundra. Most uniquely, the Arctic willow often has long trailing branches that root where they intersect with the surface of the ground, and the roots are shallow as to thrive in the frozen ground of the tundra (Wielgolaski 1972).

In addition to species such as lichens, cotton grass, and Arctic willows, shrubs, sedges, lichens, mosses, and vascular plants dominate the tundra plant community (Folch and Camarasa 2000). Despite the tundra eco-region’s reputation of being a cold and desolate ‘polar desert’, it is actually a varying landscape supporting a diverse amount of plant and animal species.

Animal species

Since the tundra has such a harsh environment, the animals who live here have adapted in a way to call the tundra their home. The keystone species of the tundra can be as small as a lemming to as large as a musk ox. The low biodiversity means that fluctuation in individual animals can have a large impact on the entire ecosystem. The main predators of the tundra are the polar bear, the Arctic wolf and the Arctic fox. They all have thick white coats that help them blend into their environment and stalk prey.[21] The polar bear spends majority of its time out on the ice hunting seals and sometimes when small rodents are scarce on land the Arctic fox will follow the bears and eat their scraps. Wolves use teamwork to attack herds of caribou or musk ox for food.[22] Lemming are small rodents that fluctuate every three to four years and with their fluctuations also comes the fluctuation of their predators such as the Arctic fox and the snowy owl.[23] The keystone herbivores are the musk ox and the caribou. They have thick shaggy coats that they shed during the warmer months.[24] Caribou use their nimble legs to escape quickly from predators while the musk ox use each other to make a fierce wall of horns.[25] These animals help keep each other alive as well as the ecosystem around them.

Geology, topography and soil

The tundra is an extremely harsh, cold, windy and unique ecosystem found on the extreme north and south latitudes of our Earth. The soil consists mostly of frozen permafrost, which makes it difficult for extended root systems to grow, water to drain and support of a wide variety of plant life. This permafrost is also responsible for creating an extremely unique topography. The land of the tundra is constantly changing as permafrost and snow melts and refreezes through the changing seasons. Land slumps and depressions occur as a result of melting permafrost that takes up less space when the soil was frozen. Depressions that occur as a result of melting permafrost are known as thermokarst, and are often in the form of pits, funnel-shaped sinkholes, valleys, ravines and sometimes caves. Pingos are another feature of the tundra, and can be defined as a cone shaped hill or mound of soil with a core of ice. Lastly, polygons make up a crucial part of the tundra and are created when two large cracks create a large ice wedge and slowly slumps into itself filling with water as heat from sunlight melts the permafrost. Often small lakes are formed from polygons on the surface of the tundra.

The flora and fauna must adapt to extremely harsh conditions, however has been able to do so successfully through evolutionary change. Many threats exist today to the tundra biome including mining, oil drilling, increased habitat loss, human habitations moving farther north and global warming which is melting more and more permafrost and changing the delicate balance of the soils. It is imperative that we fully understand how our ecosystems function in order to monitor their stability through our changing climate.

Climate

The tundra is characterized by a harsh, frost-laden landscape with negative temperatures, a lack of precipitation and nutrients, and extremely short seasons. In the winter it is cold and dark, and in the summer when the snow and the top layer of permafrost melt, it is very soggy and the tundra is covered with marshes, lakes, bogs and streams. Spring and fall are only short periods between winter and summer. In the peak of winter, average temperatures can reach −30 °F. In arctic regions, there generally is not a great difference between daytime highs and nighttime lows, as the sun generally never rises or simply hangs briefly on the horizon. Summers in the tundra, on the other hand, are very short, in some locations only lasting a few weeks. Daily temperatures can reach up to 60 °F but overnight lows go down into the 30s, 20s or lower, depending on the region. This results in daily average temperatures to come out to around 50 °F. It may rain or snow, and frost still occurs. The average annual temperature is −18 °F. Nights can last for weeks, and when the sun barely rises during some months in the winter, the temperature can drop to −94 °F. During the summer the sun shines almost 24 hours a day. Temperatures can get up to 54 °F but it can get as cold as 37 °F. Average summer temperatures range from 37 °F to 60 °F. The tundra is very much like a desert in terms of precipitation. Yearly average precipitation varies by region, but generally there is only about 6–10 inches (150–250 mm) of precipitation per year and in some regions it can have up to 20 inches (510 mm). This precipitation usually falls in the form of light, fluffy snow.

Environmental threats

Due to its vulnerable state, the powerful forces of climate change, ozone depletion, air pollution, and construction threaten the tundra's survival. The melting of permafrost increases as a result of global warming, which could drastically alter both the landscape and the biodiversity of the region. The ozone depletion at both the North and South Poles increase the strength of ultraviolet rays that harm the tundra. Air pollution around the world creates smog clouds that contaminate the lichen in the ecosystem, which is a major food source in the region. The construction of pipelines and roads to obtain oil, gas, and minerals cause physical disturbances and habitat fragmentation. There are a number of possible solutions, according to National Geographic, including switching to alternative energy, establishing protected areas and park reserves to restrict human influence, limit road construction, mining activities, and the building of pipelines in tundra habitat, and limiting tourism and respecting local cultures.[26] The creation of the Arctic National Refuge is an example of a measure being enacted to protect the North American tundra. The Arctic Refuge was originally created in 1960 by the Public Land Order 2214, which was created “for the purpose of preserving unique wildlife, wilderness and recreational values” and “withdrawn from all forms of appropriation under the public land laws, including the mining but not the mineral leasing laws, nor disposals of materials”.[27] In 1980, the Alaska National Interest Lands Conservation Act (ANILCA) re-designated the Range as a part of the larger Arctic National Wildlife Refuge, and declared “that the ‘production of oil and gas from the Arctic National Wildlife Refuge is prohibited and no leasing or other development leading to production of oil and gas from the [Refuge] shall be undertaken until authorized by an act of Congress’”.[28]

Endangered species

Though species have adapted to the harsh climate of the tundra, several species have become endangered due to changing environmental factors. Both plant species and animal species have become endangered. The Aleutian shield fern is a plant species that has been endangered due to caribou tramping and grazing, slumping from growing substrate, and human foot traffic.[29] Animal species that are endangered in the tundra include the Arctic fox, caribou, and polar bears. These animals have been endangered due to overhunting, infestation of disease, loss of diet and habitat due to climate change, and human destructive activities, such as searches for natural gas and oil, mining, and road building.[30] In an effort to conserve these endangered species, many regulations and standards are being put into action along with establishing prohibition of unauthorized plant collecting. Standards are being set in regards to mining and mineral explorations. This will help in not disturbing the habitats as much. In addition to this, protection of caribou grounds has been established along with regulations in regards to removal of gravel roads for airstrips and road fill, which takes away from many of the animals’ critical territories.

Effects of climate change

The tundra is one of the first places on Earth we have noted the impacts of climate change. As an indicator biome, the tundra is a crucial part of the whole global climate system and can help predict the changes the rest of the world will face. The Earth depends on regulating mechanisms and air circulation patterns the tundra provides to keep climates steady worldwide. Human-induced climate change is devastating the tundra because intense complications are present in remote areas, free from human interference. Changes in climate, permafrost, ice pack, and glacier formations pose a serious threat to the stability of global climate because these conditions are influenced and reinforced by positive feedback loops. Temperatures in the tundra are rising to the highest temperatures recorded in four centuries and are rising more rapidly than anywhere worldwide[31] The land surfaces in the tundra are no longer reflecting radiation from the sun out of the atmosphere. Soils and open water are absorbing heat from the sun and leading to more warming. Changes in the tundra influence climate change in lower latitudes because air pressure changes are shifting global air and ocean circulation patterns.[31] Sea ice extent in the tundra has reached lowest recorded levels in centuries and this will have dramatic impacts for people and wildlife worldwide. Changes in climate will be noticed first and seen most intensely in the northern regions of the planet. The tundra will show impacts from climate change the soonest and will hopefully serve as a catalyst for action for people all over the world.

Natural resources

According to the US Energy Information Administration, the arctic tundra holds an estimated 13% or 90 billion barrels of the world's undiscovered conventional oil sources. However, there are a number of challenges to oil exploration, drilling, and transportation in an arctic tundra environment that limits the profitability of the venture.[32] Oil and gas fields in the arctic need to be large, with lots of proven reserves, because oil companies need that money to make the investment profitable. Natural gas is a more recoverable resource than oil in tundra eco-regions. It is estimated that there are 221.4 million undiscovered, technically recoverable cubic feet of natural gas in the Arctic.[32] Oil sands, often pejoratively referred to as tar sands, are a phenomenon unique to the tundra environment and are profitable and plentiful in the Athabasca region of the Alberta sands.[33] Oil sands consist of bitumen, which contains petroleum, found in a natural state combined with clays, sands, and water.[33] Oil sands must be heavily processed and refined to yield synthetic crude oil, similar to conventional crude oil. Arctic tundra may contain minerals such as coal, copper, gold, iron, nickel, diamonds and the base feedstock for uranium oxide called pitchblende.[34]

Iconic components

The arctic tundra has an exceptionally short growing period, minimal sunlight and limited resources, creating a brutal environment for plants and animals. By adapting to these harsh conditions, animals and plants represent iconic characteristics of the tundra. Plants grow in aggregated formations which provide shelter from wind, ice and also improves seed success.[35] Animals have adapted with specialized organs, such as a rete mirabile, an organ that efficiently transfers heat. Frogs and amphibians use “anti-freeze” to prevent organ damage while hibernating. Polar bears, foxes and owls use insulated fur and feathers to protect for the cold conditions.[36] These complex interactions between plants, animals and abiotic factors in the tundra are held together by the permafrost layer, located 450 metres (1,480 ft) under the soil.[37] However climate change is causing this crucial layer of frozen soil to melt. As a result, tundra communities are becoming unstable and basic processes are breaking down. Other factors such as oil development and drilling in tundra ecosystems has completely disheveled the wildlife and vegetation populations. Tundra exploration vehicles used for oil development and polar bear tours (“an eco-friendly” industry) leave traces of tire marks for 20-plus years after disturbance occurs. Other factors such as high CO2 emissions from tourism and from warming tundra soil, creates a positive feedback loop, acceleration changes to the tundra.[38]

Tundra

Northern Arctic

Alaska Tundra

Brooks Range Tundra

Southern Arctic

Taiga

Introduction

The taiga ecoregion includes much of the interior Alaska as well as the Yukon forested area, and extends on the west from the Bering Sea to the Richardson Mountains in on the east, with the Brooks Range on the north and the Alaska Range on the south end. It is a region with a vast mosaic of habitats and a fragile yet extensive patchwork of ecological characteristics. All aspects of the region such as soils and plant species, hydrology, and climate interact, and are affected by climate change, new emerging natural resources, and other environmental threats such as deforestation. These threats alter the biotic and abiotic components of the region, which lead to further degradation and to various endangered species.

Taiga in Alaska

Soils and plant species

The main type of soil in the taiga is a Spodosol. These soils contain a Spodic horizon, a sandy layer of soil that has high accumulations of iron and aluminum oxides, which lays underneath a leached A horizon. The color contrast between the Spodic horizon and the overlying horizon is very easy to identify. The color change is the result of the migration of iron and aluminum oxides from small, but consistent amounts of rainfall from the top horizon to the lower horizon of soil.

The decomposition of organic matter is very slow in the taiga because of the cold climate and low moisture. With slow decomposition of organic matter nutrient cycling is very slow and the nutrient level of the soil is also very low. The soils in the taiga are quite acidic as well. A relatively small amount of rainfall coupled with slow decomposition of organic material allows the acidic plant debris to sit and saturate the top horizons of the soil profile.

As a result of the infertile soil only a few plant species can really thrive in taiga. The common plant species in the taiga are coniferous trees. Not only do conifer trees thrive in acidic soils, they actually make the soil more acidic. Acidic leaflitter (or needles) from conifers falls to the forest floor and the precipitation leaches the acids down into the soil. Other species that can tolerate the acidic soils of the taiga are lichens and mosses, yellow nutsedge and water horsetail. The depth to bedrock has an effect on the plants that grow well in the taiga as well. A shallow depth to bedrock forces the plants to have shallow roots, limiting overall stability and water uptake.

Keystone species

Beaver, Canadian lynx, bobcat, wolverine, and snowshoe hare are all keystone species in the taiga area. These species are keystone because they have learned to adapt to the cold climate of the area and are able to survive year round.

These species survive year round in taiga by changing fur color and growing extra fur. They have adapted to use each other to survive too. All of the predators depend on the snowshoe hare at some point during the year. All of the species also depend on forests in the area for shelter.

Hydrology

Watersheds characterize much of the taiga ecoregion as interconnecting rivers, streams, lakes and coastline. Due to a cool climate, low evaporation levels keeps moisture levels high and enables water to have serious influences for ecosystems. The vast majority of water in the taiga is freshwater, occupying lakes and rivers.

Many watersheds are dominated by large rivers that dump huge amounts of freshwater into the ocean such as the Lena river in Central Siberia . This exportation of freshwater helps control the thermohaline circulation and the global climate. Flow rates of taiga rivers are variable and "flashy" due to the presence of a permafrost that keeps water from percolating deep into the soil. Due to global warming, flow rates have increased as more of the permafrost melts every year. In addition to "flashy" flow levels, the permafrost in the taiga allows dissolved inorganic nitrogen and organic carbon levels in the water to be higher while calcium, magnesium, sulfate, and hydrogen bicarbonate levels are shown to be much lower. As a dominant characteristic in the soil, the permafrost also influences the degree to which water percolates into the soil. Where there is a year-long permafrost, the water table is located much deeper in the soil and is less available to organisms, while a discontinuous permafrost provides much shallower access.

Lakes that cover the taiga are characteristically formed by receding glaciers, and therefore have many unique features. The vast majority of lakes and ponds in the taiga ecoregion are oligotrophic, and have much higher levels of allochthonous versus autochthonous matter. This is due to glacier formation and has implications in how trophic levels interact with limiting nutrients. These oligotrophic lakes show organic nitrogen and carbon as more limiting nutrients for trophic growth over phosphorus. This contrasts sharply with mesotrophic or eutrophic lakes from similar climates.

Climate

When we look at the climate of the taiga, we are looking at average temperatures, abiotic factors such as precipitation, and circulatory patterns. According to the study in Global Change Biology, the average yearly temperatures across the Alaskan and Canadian taiga ranged from −26.6 °C to 4.8 °C. This indicates the extreme cold weather the taiga has for the majority of the year. As for precipitation, the majority of it is snow, but rain is also an important factor. According to The International Journal of Climatology, precipitation in the form of rain ranged from 40 mm average in August, to 15 mm average in April over a multi-year study. Rain is not the only kind of precipitation that affects the taiga; the main factor in precipitation is usually snow. According to CEC Ecological Regions of North America, snow and freshwater ice can occupy the taiga for half to three quarters of the year. A CEC Ecological Regions of North America document states that the lowest average precipitation is on the western side of taiga; can be as little as 200 mm and on the east coast it can be as high as exceeding 1,000 mm. As for circulatory patterns, we're finding that the temperature increases have led to a seasons shift. Global Change Biology also has noted with the change in temperature over time, as well as the overall climate change, the growing season has lengthened. Their findings illustrate that the growing season has grown 2.66 days per ten years. This growing season change as a result of global warming is having an extreme effect on the taiga.

Environmental threats

Climate change has played its role in threatening the taiga ecoregion. Equally as harmful are the human impacts like deforestation, however many associations and regulations are working to protect the taiga and reverse the damage. Climate change is resulting in rising temperatures, and decreases in moisture, which cause parasites and other insects to be more active thus causing tree stress and death. Thawing permafrost has led to many forests experiencing less stability and they become “drunken forests” (the decrease in soil stability causes the trees to lean or fall over). Increased tree death then leads to a carbon dioxide out flux, thus further propagating the increases in global warming. It is essential for climate change to be combated with global action, which is what the Kyoto Protocol in 1997 was created to do. Other measures to protect the taiga would be to prohibit unsustainable deforestation, switch to renewable energy, and protect old growth forests, (they sequester the most carbon dioxide). The taiga also suffers from more direct human impacts such as logging and mining sites. Logging has been a very profitable business in the region, however fragmentation of forests leads to loss of habitats, relocation of keystone species, increases in erosion, increases in magnitude and frequency of flooding, and altered soil composition. Regions in which permafrost has thawed and trees have fallen take centuries to recover. Canadian and Russian governments enacted a Protection Belt, which covers 21.1 million ha, and initiatives like the Far East Association for the use of non-timber forest products, gives economic significance to the forests while avoiding logging. In addition to logging, studies have measured over 99,300 tones of airborne pollutants from just one metal extracting plant over a 50-year span. These pollutants are 90% sulfur dioxide, which is a precursor to acid rain. Other emissions include nitrogen oxides, sulfurous anhydrides, and inorganic dust. Forests in a 50 kilometres (31 mi) radius of these sites can serve little to no biological services once affected, and there has been little appearance of protection measures to regulate mining plants.

Endangered species

The taiga is inhabited by many species, some of which are endangered, and include the Canadian lynx, gray wolf, and grizzly bear. The Canadian lynx is one well-known animal to inhabit the North American taiga region and is listed as threatened in the U.S. The mother lynx will have a litter of about 4 kittens in the spring. Following the birth, the female is the sole caretaker, not letting them out of her sight until 12 months when they begin to learn to hunt. According to the USDS Forest Service, protection for the lynx has increased since 2000, which marks the date it became protected under the Endangered Species Act. Since much of the lynx’s habitat is land managed by the agency, efforts to maintain and increase the habitat for the Canadian lynx using forest management plans are underway.

The taiga region is also interspersed with various plant species. The endangered or threatened species include Labrador tea, lady’s slipper orchid, helleborine orchid, long leaf pine, ligonberry plant, Newfoundland pine marten, Methuselahs beard, lodgepole pine, and Scots pine. The life history of the long leaf pine is a tree species that has been around for quite sometime, and can reach more than 250 years in age. To begin the tree’s life, a seed falls from the parent in October to late November awaiting water to begin germination in a few weeks. For those individuals that make it, they will enter what is known as the grass stage. During this stage the roots are being established, and the bud of the tree is protected from fire. Years later, the long leaf will reach about 6–10 feet (1.8–3.0 m) in height and the diameter will increase with time. Somewhere around 30 years after the trees will begin to produce cones with fertile seeds and average about 110 feet (34 m) at maturity. One recent study discusses the impacts of logging in the 1950s on pine species. Since then, conservation efforts have increased the number of pine (and other) tree species. The Nature Conservancy is prioritizing its protection efforts to rebuild long leaf pine forests through land purchases, conservation easements, and management of land sites. Restoration is also a large part of efforts to ensure the long leaf pine remains extant. By planting seedlings, controlling competitive vegetation, and controlled burning methods, scientists and volunteers are working to increase the number of the long leaf pine.

Canadian lynx near Whitehorse, Yukon

Effects of climate change

Over the next 100 years, global annual mean temperatures are expected to rise by 1.4−5.8 °C, but changes in high latitudes where the boreal biome exists will be much more extreme (perhaps as much as a 10 °C rise). Warming observed at high latitudes over the past 50 years exceeds the global average by as much as a factor of 5 (2–3 °C in Alaska versus the 0.53° global mean).

The effects of increased temperature on boreal forest growth has varied, often depending on tree species, site type and region, as well as whether or not the warming is accompanied by increases or decreases in precipitation. However, studies of tree rings from all parts of the boreal zone have indicated an inverse growth response to temperature, likely as a result of direct temperature and drought stress. As global warming increases, negative effects on growth are likely to become more widespread as ecosystems and species will be unable to adapt to increasingly extreme environmental conditions.

Perhaps the most significant impact of climate change on the boreal region is the increase in severity of disturbance regimes, particularly fire and insect outbreaks. Fire is the dominant type of disturbance in boreal North America, but the past 30 plus years have seen a gradual increase in fire frequency and severity as a result of warmer and drier conditions. From the 1960s to the 1990s, the annual area burned increased from an average of 1.4 to 3.1 million hectares per year. Insect outbreaks also represent an increasingly significant threat. Historically, temperatures have been low enough in the wintertime to control insect populations, but under global warming, many insects are surviving and reproducing during the winter months, causing severe damage to forests across the North American boreal. The main culprits are the mountain pine beetle in the western provinces of British Columbia and Alberta, and the spruce bark beetle in Alaska.

Traditional and emerging natural resources

Taiga (boreal forests) have amazing natural resources that are being exploited by humans. Human activities have a huge impact on the taiga ecoregions mainly through extensive logging, natural gas extraction and mine-fracking. This results in loss of habitat and increases the rate of deforestation. It is important to use the natural resources but its key to use natural resources sustainably and not over exploit them. In recent years rules and regulations have been set in place to conserve the forests in order to reduce the amount of trees that are cut. There has been an increase in oil extraction and mining throughout the United States and Canada. Exploitation of tar sands oil reserves has increased mining. This is a large operation that started in Alberta Canada. Oil extraction has a direct effect on the taiga forests because the most valuable and abundant oil resources come from taiga forests. Tar sands have affected over 75% of the habitat in Alberta taiga forest due to the clearing of the forests and the oil ponds that come from the extraction. These tar sands also create awful toxic oil ponds that affect the wildlife and surrounding vegetation. Oil extraction also affects the forest soil, which harms tree and plant growth.

Today, the world population has an increasingly high ecological footprint and a large part of that has to do with the populations carbon footprint. As a result of that, oil supplies have increased, which has spread across the U.S. and into other countries. This is detrimental to natural ecosystems. Taiga being the largest region is seeing major consequences of our actions on extracting oil and natural gas. This is also causing climate change temperatures to increase at a rapid rate, which is affecting wildlife and forests. However, even though Human activities are responsible for the exploitation of these natural resources humans are the solution and have the tools to fix this issue. It is crucial that humans reduce the consumption rate of these natural resources in order to increase environmental conditions.

References

Alaska Boreal Interior

Taiga Cordillera

Taiga Plain

Taiga Shield

Hudson Plain

Hudson Plain

Northern Forests

Softwood Shield

Mixed Wood Shield

Atlantic Highlands

Boreal Plain

Northwestern Forested Mountains

Hydrology: Major watersheds, rivers, and lakes

Crater Lake, Oregon

Most of the water in this ecoregion is fresh water and contained in rivers, lakes, and ground water. Washington, Oregon, and Idaho are mainly drained by the Columbia River, its tributaries, and other streams that flow to the Pacific Ocean. The Columbia River Basin is the fourth largest watershed in North America. According to a 2004 GIS inventory by the Environmental Protection Agency, there are approximately 10,535 lakes and reservoirs in the Pacific Northwest. The largest lakes in the Pacific Northwest include Lake Washington, Lake Roosevelt, Lake Chelan, Upper Klamath Lake, Lake Pend Oreille, Priest Lake, and Lake Coeur d’Alene.

In British Columbia the Fraser River watershed covers one-fourth of the land and extends from Mount Robson to the Georgia Strait and Gulf Islands. This basin is the fifth largest drainage basin in Canada and contains thirteen main sub-watersheds, each consisting of small rivers, streams, creeks, marshes, bogs, and swamps. The largest lake in British Columbia is Williston Lake which covers 680 square miles.

Alaska contains abundant natural resources which include ground and surface water. The southwestern part of Alaska is drained by the Yukon River and its tributaries that include the Porcupine, Tanana, and Koyukuk Rivers. The Yukon River is the third longest river and fourth largest drainage basin in North America with a drainage area of 832,700 square kilometers. Alaska contains over three million lakes and the largest is Lake Iliamna which covers an area of 1,000 square miles.

Vegetative cover

Vegetative cover is extremely diverse within the northwestern forested mountain ecological region as the region can be broken down into different zones based on elevation, temperature and mean annual rainfall. Alpine communities; areas of high elevation (> 8,200 feet) can support the growth of herbs, grasses, lichen, and shrubs well adapted for these harsh conditions. Common plants here include mountain sorrel, capitate sedge, mat muhly, Newberry knotweed, and red huckleberry. Lichens such as the witch’s hair lichen and cup lichen also persist here. Subalpine communities; located below the alpine communities (6,500-8,200 feet) support the presence of lodgepole pine, subalpine fir, pacific silver fir, grand fir, and Engelmann spruce. The Engelmann spruce–subalpine fir forest association occupies the greatest water-yielding areas in the Rocky Mountains and the natural adaptations of these trees are important in maintaining stable vegetation. The mountainous slopes and rolling plains slope from about 5,500 feet at the foot of the Rocky Mountains to about 2,000 feet in the lowest elevations. The dominant trees present in the region consist of; ponderosa pine, Rocky Mountain Douglas fir, lodgepole pine, and quaking aspen the drier southeast and central portions. Western hemlock, western red cedar, Douglas fir, and western white pine make up the majority of the moist west and southwest portions. White spruce is also found at this elevation and is a keystone tree species found in the Alaskan interior. The dry southern interior grasslands and forests generally occur at low elevations (under 4000 feet) and usually have a lower canopy closure than forests at higher elevations that receive more precipitation They are characterized by very warm to hot, dry summers, and moderately cool winters with little snowfall. Frequent low-severity, ‘‘stand-maintaining’’ fires are thought to have played a key historic role in shaping these ecosystems. Much of this area consists of small scrub like ponderosa pine with bluebunch wheatgrass, blue grass, June-grass, and big sagebrush dominating the understory.

Fauna

This ecoregion is abundant with varying types of mammals, fish, and birds. Many dominant animal species, such as the bighorn sheep and hoary marmot, have adapted to the terrain of the region. The talus slopes provide burrowing shelters for the hoary marmot, and the bighorn sheep have adapted to climb the steep slopes in order to find shelter from predators (National Park Service). Top carnivorous predators include coyotes, wolves, and cougars. The grizzly bear is a keystone species found in this region. As an “ecosystem engineer”, they regulate the species they prey on, disperse plant seeds, aerate the soil as they dig, and bring salmon carcasses into the forest (Suzuki). The dominant fish species of the region, in which the grizzly bear preys on, is pacific salmon. The typical bird species that can be found here include blue grouse, Steller’s jay, and black-billed magpie (Commission for Environmental Cooperation, 2008).

Endangered species

The northern spotted owl (Strix occidentalis caurina) is considered a species of utmost concern in the Northwestern Forested Mountains region. This small raptor was listed as threatened under the Endangered Species Act of 1973. The current population is 15,000 birds, all of which are located in North America. Over 70% of the species’ habitat was destroyed in the 19th and 20th centuries, and the timber industry is causing that number to increase. Both northern spotted owls and the timber industry prefer old-growth forests, so as demand for timber products increases, the spotted owl’s habitat decreases. Forest management plans that stress limits on timber harvest and suggest alternative options are being formed, along with plans to prevent habitat fragmentation.

The barred owl is also causing a decrease in the population numbers of the northern spotted owl, as they are a larger, more competitive species that have begun to use the same habitat, however, no major plans have been formed to manage this situation.

Malheur wire-lettuce (Stephanomeria malheurensis) is also an endangered species in the region. Only one population of this plant survives in the wild, located in Harney, Oregon. The self-pollinating shrub is found at high elevations in volcanic soils. Because the range is so small, any disturbance in the habitat could be detrimental. One of the main threats is Cheatgrass, which can expand to completely cover the ground and use up resources also needed by Malheur wire-lettuce. It is generally agreed that in order to protect the species, efforts must be focused on forming new populations, and more importantly, maintaining the condition of the current site in Oregon.

Natural resources

The Northwestern Forested Mountain ecoregion is rich in natural resources. Historically the most sought after resources were the minerals found here. The presence of gold drove much of the early settlers to this ecoregion. These early settlers extracted gold from the streams, and timber for building, flora, and fauna. Today many more resources are utilized by the economies of this area. Large scale mining operations have become less common throughout the entirety of the region. There are a few prospective industrial mines lobbying for permitting to dig in both Canada and Alaska. Canada is the 6th-largest petroleum producer in the world. The largest point of extraction within this ecoregion is in Alberta, Canada. This area is abundant in tar sands, a crude form of petroleum. In order to begin this operation large tracts of boreal forest are removed. After the large pits are dug there is a constant risk of further environmental degradation through oil spillage. Logging in the past was often conducted through large clear cuts. The environmental impacts of large clearcuts became apparent and are now less common. There are logging techniques that can benefit the ecological integrity of a system. Group selection can mimic natural processes and increase both horizontal and vertical structure to a forest. As well as increase biotic diversity of both flora and fauna. Tourism generates a considerable amount of revenue for the different economies of this area. Tourists come to these areas for a multitude of outdoor activities. In the winter tourists travel from all across the globe to ski the Rocky Mountains, British Columbia, and Alaska ranges. In the summer the national parks draw in millions. Other summer activities include but not limited to hunting, fishing, mountain biking, backpacking, rafting, kayaking, and wildlife viewing/ photography. Resource use and extraction is sustainable when a system can replenish resources faster than they are being used. A practice is unsustainable when usage exceeds this threshold thereby damaging the ecological integrity of the ecoregion.

Climate

Extending from the lower Yukon of Canada all the way into northern California and Nevada, the northwestern-forested mountains range in different about three climate zones; moist maritime, arid dry, and sub arctic.

The moist maritime climate of the Northwestern Forested Mountains is found along a narrow strip of coastal Oregon, Washington, British Columbia, and southern Alaska in North America. It is formed by westerly winds coming off of the Pacific Ocean, which hit the mountains and rise to a cooler atmosphere. This causes rainy, cloudy, and moist atmospheric conditions where up to 100 inches of rain per year can be seen, and is a temperate zone ranging from about 15 °F in the winter to about 65 °F in the winter.

The arid dry zone is west of the mountain ranges and doesn't receive much rain due to the north to south orientation of the mountains, which block clouds and precipitation. It can range from the upper 80s (°F) in the summer to single digits in the winter. It generally only receives about 20 inches (510 mm) of rain per year.

The sub arctic region ranges from Fairbanks, Alaska to the Yukon of Canada and averages a mean of 50 °F. in the summer and is often negative 13 in the winter. On the mountain tops it can receive up to 100 inches (2,500 mm) of precipitation per year, and often considered the snowiest place on earth.

The Northwestern Forested Mountains experience phenomena called decadal oscillations, the La Niña and El Niño. This is a shift in temperatures from warmer (La Niña) to colder (El Niño) and each phase generally last about a decade. These phases are caused by many factors including, jet streams, trade winds, precipitation, land surface, temperature, ocean surface temperature, and sea level pressure.

Environmental threats to the Northwestern Forested Mountains

The biggest threats to this region are fires and invasive pests. As fires occur, they alter the forest composition dramatically. Fire scars create entry for heart rot and other fatal conditions. Burned soils repel water and the runoff creates sediment and ash polluting rivers and streams, harming fish and wildlife that depend on these water sources. An especially troubling aspect of fires’ aftermath is the increased vulnerability of trees to non-native invasive pests. Burned stands create a perfect habitat for pests who will find shelter in the regrowth. These pests create tunneling galleries that further weaken a tree’s ability to fend off pathogens that lead to mortality.

Preventing forest fires and controlling pest populations go hand-in-hand, which leaves room for any combination of treatment plans. Especially helpful is the use of prescribed burns, which consists of randomly dropping a match on a grid that has been divided and planted at scattered time periods. After the fire, workers must go in to peel bark off felled logs, and, if possible, remove dead, dying, and severely damaged/stressed trees as soon as possible.

Climate change in the Northwestern Forested Mountains

The effects of fossil fuels emissions, the largest contributor to climate change, cause rising CO2 levels in the earth’s atmosphere. This raises atmospheric temperatures and levels of precipitation in the Northwestern Forested Mountains. Being a very mountainous region, weather patterns contribute higher levels of precipitation. This can cause landslides, channel erosion and floods. The warmer air temperatures also create more rain and less snow, something dangerous for many animal and tree species; with less snow pack comes more vulnerability for trees and insects.

A large contributor to fire susceptible forests is past land use; the higher air temperatures make wildfires more common. Wildfires are extremely detrimental for species inhabiting the landscape; they destroy habitats and it takes many years to restore the land to how it used to be.

These effects caused by climate change can destroy animal habitats and species diversity. Not only will these climate catastrophes directly reduce animal populations, but it will indirectly disrupt trophic levels by reducing food sources for many keystone species. Climate change contributes to a worsening economy in this region as well by taking away valuable resources for recreational uses, like snow for skiing and fish for fishing.

Boreal Cordillera

Western Cordillera

Marine West Coast Forest

Topography/geography/soil

The region is strongly influenced by the large mountain ranges stretching throughout most of the coast. Changes in elevation cause changes in plant/animal diversity, this can be exemplified through observing the alpine tundra's vegetation which consists of shrubs, herbs, mosses, and lichens; while lower elevations, the temperate coastal forest hold magnificently large trees such as western hemlock, California redwood, and the red alder. These differences are in direct correlation with the availability of oxygen, and other nutrients at higher elevations.[39] The mountains also create rain-shadow areas due to the clouds having to release their precipitation in order to get over the mountains, or be blocked all together. Trees, which perform better under stress, grow in these areas such as the Douglas fir (www.countriesquest.com). As for the soil, the region generally has a thin podzol soil, causing it to be extremely acidic. Farmers must compensate by applying fertilizers and lime to lower the acidic levels for agricultural viability.[40] Digging even deeper the then soil within the region will reveal mostly igneous and sedimentary rock. Colluvium and morainal deposits make up most of the surface materials. Mountains, which have such an intense impact on the region, are massive formations resulting from upheaval caused by continental collisions[41]

Climate

The climate of the marine west coast forests is humid. According to the Köppen climate classification System, this climate is very damp throughout most of the year, receiving a great amount of rainfall along with heavy cloud cover. The marine climate can also be defined with its narrow range of temperatures throughout the year. Precipitation is ample and consistent in the marine west coast, with many days of rainfall and a large annual accumulation. Many areas in the marine west coast climate have more than 150 days of rainfall per a year, along with averaging around 50 to 250 centimeters per a year of total rainfall (Britannica, 2013). The average temperatures of areas within the marine west coast forests usually range from 10 °C to 15 °C (Britannica, 2013).

These mild temperatures are in collaboration with the moderating impact of ocean bodies on air temperatures due to the constant influx of oceanic air influencing the marine west coast throughout the year (Ritter, 2009). The marine west coast is located in the path of westerly winds from the ocean that contribute to its cloudy skies, significant amount of precipitation, and mild temperatures (Hollow, 2001). The rainfall, seasons, and temperature are all dependent on each other and are all affected by the global circulatory pattern.

Hydrology

The main watersheds in the region are the Puget Sound and Columbia River Watershed. Due to the region’s proximity to the Pacific Ocean, this ecoregion experiences large amounts of precipitation annually, creating a very humid and wet climate. The majority of river and stream activity is directly influenced by the annual precipitation patterns. In the rainy season from October to May, most of the low elevation rivers and streams experience peak run off levels. Rivers and streams at higher elevation are more influenced by snow melt and therefore experience peak run off from late spring into early summer due to the snowmelt. The permeability levels of bedrock in the area of interest dictate surface water in the region. Volcanic parent material, as found in Oregon, tends to result in lower levels of ground water due to the low permeability of the rock. Although areas with volcanic parent material may have fewer ground water aquifers, these areas tend to have better developed stream networks and higher stream drainage levels (Moore, 765). Areas with newer volcanic bedrock have higher levels of permeability, and are therefore more likely to have ground water aquifers. These areas will experience lower stream drainage densities and less developed stream networks due to the greater rate of ground water recharge (Moore, 765).

Keystone plants

The plants in this region are responsible for holding the geography and geology of the area intact. The North-South orientation of the mountain ranges combines with the moist polar air masses and mild westerlies coming eastward off the Pacific Ocean to form a weather pattern that dominates the area. This pattern consists of a temperate moist zone on the west side of the mountains and a drier moderate climate on the east side. The moist conditions along with glacial valleys cut by the glaciers allow for a variety of plant life to thrive.

The softwood stands of the highlands are keystone species in maintaining land integrity. The ability of the firs and spruces to populate the high altitude and shallow soil works like glue to hold the soil in place. As you drop in altitude pines and cedars do the same for the lower slopes. Erosion control is key to keeping the glacial valleys and their rivers free from silt build up, which has the ability to devastate the salmon population, as well as holding the integrity of the mountain ranges.

Dominant species

Marine West Coast Forests combine aquatic ecosystems with temperate rainforests to provide habitat for an abundance of wildlife. The sea otter is considered a keystone species because of the critical role it plays in maintaining the structure of the ecosystem. Sea otters feed on sea urchins, which are herbivores of kelps. A large mass of kelp can become an underwater kelp forest, which is considered by many to be one of the most productive and dynamic ecosystems on Earth. Two more dominant species found in the Marine West Coast Forest are the gray wolf and the grizzly bear. Both predators regulate elk populations, which tend to over-browse many shrub species in riparian zones. With less elk browsing, the riparian zones can provide habitats for birds and help maintain a healthier marine ecosystem. In addition, grizzly bears provide a connection between the marine coast and the forests when they eat nitrogen-rich salmon and transfer the nutrients to the forests. The Pacific salmon provide strong sources of nitrogen for the aquatic ecosystems. Due to the high precipitation in this Eco region, the nitrogen levels can be very low. The Pacific salmon helps to normalize the nitrogen levels. Without anyone of these species, the ecosystem would fall apart. The Marine West Coast Forests are a unique habitat for a diverse group of species.

Threatened and endangered species

Several species struggle to survive in the ever disappearing and degrading ecosystems of the northwest. These species face a high risk of extinction; some iconic examples of those listed as threatened or endangered in this ecoregion include the giant sequoia, coast redwood, and marbled murrelet.

The giant sequoia and coast redwood are listed as a vulnerable under the IUCN Red List standards (Conifer Specialist Group 1998). Large-scale logging, felling 90 to 95 percent of the old-growth forest between 1856 and 1955, is primarily to blame for these species’ now limited range. The remainder of most populations of giant sequoias and coast redwoods is now almost entirely in parks and reserves (Farjon & Page 1999). Fire prevention policy, however, is most to blame for the continued declining of populations, as the build-up of undergrowth hampers the regeneration of both species (Vankat 1977). Luckily, plans to improve management and plant trees on cleared land are in place (Farjon & Page 1999).

Though the marbled murrelet is still considered abundant, its population has undergone a rapid decline, principally because the old-growth forests in which they breed are subject to logging (Piatt et al. 2006). Current estimates are nearly half of historic numbers, suggesting just 350,000 to 420,000 remain (Piatt et al. 2007). The IUCN has listed the species as endangered (BirdLife International 2012). Hard forest edges resulting from forest fragmentation greatly subject murrelet nests to corvid predation and other associated disturbances (Peery et al. 2004). Declines in areas where logging is not an issue can be explained by the overexploitation and subsequent collapse of the pacific sardine fishery. Nylon gill-nets in shallow waters and oil spills have cause considerable mortality, as well (Piatt & Naslund 1995). In response, conservation measures have been implemented to slow the species’ decline, including: the prevention of logging within identified breeding areas (Nelson 1997), the development of detailed research and recovery plans (Kaiser et al. 1994, CMMRT 2003, Escene 2007), and the protection of 179 square kilometers on Afognak Island by the Exxon Valdex Trustee Council (EVOSTC 1995).

Environmental threats

The Marine West Coast Forest's primary environmental threats are human development and population growth, logging, spruce bark beetle populations, and invasive species. This ecological region is home to large cities like Vancouver, Portland, Anchorage, and Seattle. As these cities continue to grow in population, greater tracts of land are being developed, and more resources are needed to accommodate these higher populations. Logging is another large human induced environmental threat to the ecoregion. Logging causes habitat fragmentation and adversely affects important species such as spotted owl, grizzly bear, and Kermode "spirit" bears, who all require large tracts of land to survive (Demarchi, Nelson, Kavanagh, Sims, Mann, 2013). The spruce-bark beetle is an insect that destroys spruce trees by tunneling into the bark of the trees. These beetles are widespread in the northern part of the ecoregion in states such as Alaska (Alaska Department of Fish and Game, 2013). The beetle’s distribution and survival rate has increased in the last decade due to climate change. Invasive species are also rampant in the ecoregion. These foreign plants and animals disrupt naturally occurring species in the ecoregion. Several solutions have been enacted to solve the environmental threats of the Marine West Coast Forest. Public land ownership is positively correlated with environmental preservation, as seen by the parts of the ecoregion located in Alaska (Alaska Department of Fish and Game, 2013). When land is privately owned, the most effective measures are education of the beautiful natural areas, smart land use, and planned efficient growth (Oregon Department of Fish and Wildlife, 2006).

Climate change

The Marine West Coast Forests are located along the coast and some islands of northern California up to Alaska. The rise of the sea level will increase soil erosion of these marine areas (Coastal Areas Impacts and Adaptation). Depending on to what degree the sea level will rise, the introduction of salt water to the soil in the marine forest can slow and or destroy the growth of marine forest plants as well as the habitat of forest animals (Oberrecht). Freshwater flow will greatly disrupt the ecology of the Marine West Coast Forest. The trend seems to be that wet regions are getting wetter and the dry regions are getting drier (Song). The Marine West Coastal Region is a wet region that will most likely see these increases in precipitation levels.

The precipitation level increasing will change the stream chemistry of vital spawning areas for salmon. Spawning salmon are most successful when the water is cold and with a steady flow (Coastal Areas Impacts & Adaptation). The rising temperature of the streams from rainfall instead of snowfall will be more likely to also develop and spread disease through salmon (Coastal Areas Impacts & Adaptation). The estuaries, where the ocean and river water meet is a very vulnerable area. The rising sea level will bring more salt water into the estuaries (Oberrecht). The salinity of the water will increase further up rivers and this can alter the mixing and flushing rates of the estuary, increasing pollution dramatically (Oberrecht). The change of balance in an estuary will also decrease the buffer effect that estuaries have against storms (Oberrecht).

References

Marine West Coast Forest

Mediterranean California chaparral and woodlands

Silverado Canyon and chaparral habitat, in the Peninsular Ranges of Southern California.
California oak woodland habitat, of the California chaparral and woodlands ecoregion, in San Luis Obispo County.
Redshanks (Adenostoma sparsifolium) and bigpod ceanothus (Ceanothus megacarpus), in chaparral habitat of the Santa Monica Mountains.

Climate

Very few places in the world have the Mediterranean climate of California. It is one of the more rare in the world, with only five locations: the Mediterranean Basin, Southwest Australia, the Cape Province—Western Cape of South Africa, the Chilean Matorral, and the California chaparral and woodlands ecoregion of California and the Baja California Peninsula. The region is typified by warm dry summers and mild wet winters. This is unusual as most climates have more precipitation in the summer. There are three variations to the Mediterranean climate in California, a cool summer/cool winter variation, a cool summer/cool winter with summer fog variation, and a hot summer/cool winter variation. The average temperatures for the cool summer variations are below 71 °F in the summer and between 64 and 27 degrees Fahrenheit in the winter. Average summer temperatures for the hot summer variation are above 71 degrees Fahrenheit. Average annual precipitation for this climate is 25–100 inches (640–2,540 mm) per year.

Hydrology

Defined by the Pacific Coast on the west, the Sierra Nevada (mountains) and the deserts of California on the east, and the Northern California Coast Ranges on the north, the Mediterranean California ecoregion has unique physical characteristics that play a large role in the natural systems of the region, including hydrology.

Precipitation

The unusual precipitation pattern of the Mediterranean climate is due to subtropical high-pressure systems in the summer and the polar jet stream in the winter. Rainfall in the summer is uncommon because the marine layer becomes capped with dry sinking air. The marine layer is an air mass over a large body of water brought about by a temperature inversion from the cooling effect of the water on the warmer air. The marine layer is often accompanied by fog. The polar jet stream in the winter brings with it rain and snow. The jet stream is an extremely powerful air current flowing west to east often at over 100 miles per hour.

The precipitation in the region is closely associated with winter frontal storms from the Pacific Ocean, which bring cool air and rain to the area. The annual rainfall varies in different elevations, but the average range is between 400–800 millimetres (16–31 in) annually. Much of the rain in Central and Northern California flows out the Sacramento and San Joaquin Rivers, which with numerous tributaries run through an upper part of the ecoregion.

Fog is also an important aspect of the hydrologic cycle in this ecoregion; the cooling of air over the warm seawater create an dense fog that covers large areas of the coast. This fog affects the vegetation and overall environment on the coast. On the contrary, fire also influences this region. The fire-flood sequence that occurs post-fire can greatly effect populations of species in the region. The combination of the geophysical characteristics, little rainfall, and the bodies of water in the region make it a unique, distinct environment.

Geology

Mediterranean climate California's geology is characterized by the meeting of the North American Plate and Pacific Plate, with much of its region near or influenced by the San Andreas Fault along the junction. When the two plates collided the Pacific Plate was pushed under the North American Plate, and the California Coast Ranges and Sierra Nevada were uplifted. The Coast Ranges are largely metamorphic rock formed from the submergence of the Pacific Plate, and the Sierra are uplifted granite batholiths. Not along the San Andreas Fault, the granitic Peninsular Ranges system also uplifted with the collision, and runs from Southern California, down the Baja California Peninsula, into Baja California Sur state, northwest Mexico. The Transverse Ranges are another major Southern California mountain system primarily in the Mediterranean climate zone. Large earthquakes can do considerable damage to populated areas, and to the state's water, transportation, and energy infrastructure.

The Central Valley of California is a significant feature of Mediterranean climate California. It was an ancient oceanic inlet that eventually sediment filled in, the deposition supplied by erosion of the surrounding mountain ranges. The soil is composed of both the metamorphic, oceanic crust-like Coastal Range sediment and the mineral-rich granitic Sierra sediment. The combination creates very fertile soil. The flatness and fertility of the soil, along with the almost year-round sunshine has attracted much agriculture to the area. As a result, native species no longer dominate the landscape. The southern portion, named the San Joaquin Valley, also produces two-thirds of California’s oil from underground reserves. Fossils are found where adjacent tar pits occur.

California towhee (Pipilo crissalis), in San Luis Obispo.
Palos Verdes blue (Glaucopsyche lygdamus palosverdesensis), butterfly endemic to the Palos Verdes Peninsula.

Biota

Dominant animal species

The Mediterranean California ecoregion, is well known for its large variety and abundance of animals. One of these important animals is the American golden eagle, which plays a massive role in maintaining the ecoregion’s ecosystem through its top-down predation on smaller, more abundant animals. The golden eagle is considered to be the apex predator of this community, and there are no other species bigger than them on the food chain. Their lifespan can be up to around 30 years in the wild and even longer in captivity. Native to mountain areas and grasslands, California is a great region for this bird of prey to thrive in. The main reason for the golden eagle being a keystone species of this ecoregion is their ability to keep small herbivorous mammal populations in line. “Prairie Dogs, ground squirrels, other rodents, hares, and rabbits, all of which eat grass and seeds, constitute 77.9% of the golden eagles diet." They also are known to prey on animals such as, cranes, black-tailed jack rabbits, swans, deer, coyotes, badgers, mountain goats, bobcats, and various fish species.

Another less popular species, but yet still keystone to this region, is the kangaroo rat. Studies have shown that kangaroo rats play very large roles in maintaining the population sizes and animal diversity throughout the region. Although they are small and on the verge of extinction, these animals play a large role in maintaining plant diversity, which helps the various herbivores with food supply, and also protection for other small animals seeking shelter. kangaroo rats occupy many land habitats ranging from desserts, and grasslands, to chaparral areas making them present in all areas of the Mediterranean California ecoregion. Kangaroo rats like to feed on many various grass seeds, as well as mesquite beans and thus is the reason that plants tend to not grow as well when sharing the same community with these rats. On occasions though, these animals like to feed on green vegetation, and insects. Unfortunately for the rat though, it is preyed upon by many predators. These predators include, owls, snakes, bobcats, foxes, badgers, coyotes, cats and dogs, and many more. Other dominant species in the region include, mountain lions, coyotes, sea otters, brown bears, and various large birds of prey.

Dominant plant communities

California poppy (Eschscholzia californica) field, at the Antelope Valley California Poppy Reserve.

The vegetation in the Mediterranean California ecoregion is a mixture of grasses and shrubs called chaparral with some oak forests as well. This area is very highly populated and agriculture is prevalent in the valleys (Comm. of Env. Coop. 2011). Evergreen trees and shrubs—such as heaths—mainly dominate Mediterranean vegetation with a shrubby to herbaceous understory. Mediterranean vegetation embodies less than 5% of terrestrial ecosystems around the world. A very important aspect of this ecosystem is its frequent wildfires leading to most of its vegetation adapting fire response mechanisms (Vilà and Sardans 1999). Common shrubs within this region are chamise or greasewood (Adenostoma fasciculatum), manzanita (Arctostaphylos spp.), coast sagebrush (Artemisia californica), and California-lilacs (Ceanothus spp.) (Conrad 1987).

Because the climate is so dry and experiences frequent fires, competition is high among plants within this ecoregion. The Mediterranean community found in southern California is said to have a successional stage after wildfires. The fire leaves patches of bare ground which then are quickly filled with newly germinated seeds. Native and introduced herbs persist for the first year following a fire. Shrubs and subshrubs slowly fill in and hit their peak at four to eight years after the fire. Extinctions, unlike many other communities are frequently the cause of environmental extremes rather than competitive invasive species (Zedler et al. 1983). Human disturbance can increase wildfires with the introduction of grasses such as Bromus rubens which can be readily established in the newly burned, cleared patches. These grasses are more densely compacted and create more fuel for fires. Agricultural grazing can also greatly decrease the chaparral (tangled shrubby brush habitat), which is the home of many native endemic species (Fleming et al. 2009, Zedler et al. 1983).

California condor (Gymnogyps californianus) in flight.
San Joaquin kit fox (Vulpes macrotis subsp. mutica), sitting.

Endangered species

An endangered species is a species of organisms, either flora or fauna, which face a very high risk of extinction in a proximate time frame, much sooner than the long-term horizon in which species typically persist. There are many species of birds, mammals, reptiles, amphibians and plants that live in the Mediterranean California chaparral and woodlands ecoregion. Yet due to a variety of factors including habitat loss due to the 30 million humans who share the land, some species are endangered.

Endangered, threatened, and vulnerable species of the Mediterranean California chaparral and woodlands ecoregion include:

The California condor (Gymnogyps californianus) is one of the most iconic species in the state. With over a 9 feet (2.7 m) wingspan, condors are the largest flying land bird in North America. They are opportunistic scavengers that prey on large dead mammals. The main factors that led to the species endangered status were settlement of the west, shooting, poisoning from lead and DDT, egg collecting, and general habitat degradation. Serious conservation efforts have been made since the 1960s and this severely endangered species has begun a recovery path. A condor recovery program has been started and a wild population is steadily growing.

Another species is the tiny and secretive San Joaquin kit fox (Vulpes macrotis subsp. mutica) is one of the most endangered animals in California. The kit fox is the size of a cat, with big ears, a long bushy tail and furry toes that help to keep it cool in its hot and dry Californian Mediterranean environment. Biologists state that there are fewer than 7,000 San Joaquin kit foxes. San Joaquin kit fox populations rise and fall with the amount of annual rainfall: more rain means more kit foxes. Changes in precipitation patterns, including reduced rainfall and increase changes of drought, all caused by climate change, would have an impact on San Joaquin kit fox populations. The change in the Central Valley from open grasslands to farms, orchards, houses and roads has had the greatest impact on San Joaquin kit foxes, causing death, illness, injury, difficulty in finding a mate and difficulty in finding food. These kit foxes also are killed and out competed for resources by coyotes and red foxes. Another threat is poison used to kill rats and mice. A recent decision by the federal government to limit to use of these poisons outdoors may keep kit foxes safe.

Natural resources

Humans have used resources of this ecoregion for many years, dating all the way back to early Native Americans. Some traditional resources that are still used today are in danger of being overharvested. These include the Pacific ocean fisheries, the dwindling timber industry, the rivers flowing from the mountains and the grasslands. All of these resources are either being over harvested or destroyed through agricultural and industrial development. Grasslands hold many native oak trees that are being lost due to overgrazing or forest fires. The overgrazing is attributed to the increasing number of cattle farms while the forest fires come from the use of natural water for human and agricultural use. As more water is used, oak trees lose out without this key component and fires increase due to drying out of the grasslands and forests. The government has tried to install conservation programs to halter the increased use of the land and waterways, but more must be done to create a truly sustainable environment.

Emerging resources from the region are mainly high value agricultural crops. These include stone fruits, sugar beets, rice, nuts, grapes, cotton and specialized cattle systems. Many of these cannot be grown in other parts of the country and thrive in this type of climate. However, because of the dry seasons, these products require large amounts of water as well as varied chemicals and fertilizers to increase production. Many of these farming enterprises are enormous and not sustainable. They leach out chemicals, bring in mass amounts of inputs, and degrade a lot of the land. As with the traditional resources, the government has implemented conservation programs, but only a limited amount.

Climate change

Climate change in the Mediterranean California ecoregion is expected to ultimately have negative effects on the ecosystem and the region's biodiversity. The coast of California is expected to warm by as much as 2 °C in the next 50 years. This is going to cause hotter and drier seasons; the normally wet winters (when a majority of the ecosystem's rain in received) will be drier, and the summers will be especially hotter as well. Increased wildfires will result from the region's warming – mainly in the summer. The shrubbery and trees characteristic of the California chaparral will not fare well in the warmer (and increased fire) region; grasses that are able to regrow asexually or from special off chutes will fare the best. Ultimately the soil quality is going to degrade due to the increased burnings and increased temperatures. Overall, climate change does not bode well for the Mediterranean California ecosystem.

Environmental threats to the region

There are several large threats to this region. Many of California’s large population centers are located within it which causes stress on the surrounding environment because people have a desire to move to California so new homes and industry have to be established in order to accommodate all of the people moving into the region and this requires expansion. Research shows that this eco region is already 20% urban environments and 15% agricultural lands. The research also concluded that population density and urban area has increased by 13% between 1990 and 2000 while agricultural lands in the region have only expanded by 1%. The study conducted also showed direct relationships between the growth of the population and the number of species that were threatened in the area. Expansion will break up the contiguous landscape and move humans closer to the native flora and fauna which will over pressure species that need large open tracts of land to thrive and harm the species diversity of the region. Prevailing winds coming from the west off of the Pacific Ocean all of the pollution created gets carried up to these higher inland sites and causes the species there to suffer with the pollution generated.

The region is also plagued by wildfires. The area is becoming arid species diversity will drop as organisms adapted for dryer climates thrive. No current management plans are in place, a Species refugia to save struggling species that inhabit this region has been proposed by some. Forests similar to these are more resilient to such events due to the spatial arrangement, it would be possible to replicate this in the current forest and make it resilient to the fires that will increase in the near future.

Humboldt lily (Lilium humboldtii), endemic to Southern California.

See also

California red-legged frog (Rana draytonii), a vulnerable species.

Sources cited

25 Feb. 2013.

[42]

Eastern Temperate Forests

Description

The Eastern Temperate Forests of North America are a vast and diverse region. Stretching inland from the Atlantic coast about 385 miles (620 km), they reach from Michigan in the north and Texas in the south; they cover the land of New England to Florida, Alabama to Michigan, and Missouri to the Appalachian Mountains. This ecoregion enjoys a mild and moist climate, though it is generally warmer as latitude decreases and drier as longitude increases.[43] Warm summers and mild to cool winters have provided favorable growing conditions for a number of plant species, the dominant being large, broadleaf, deciduous trees and (to a lesser extent) needle-leaf, coniferous, evergreen trees. Indeed, before the arrival of Europeans, this area was almost completely forested. After their arrival a few centuries ago, much of the eastern forests had been cleared for timber and to make way for cropland. In more recent time, however, these open areas have been abandoned and are slowly returning to forest. Although heavily influenced by people, the Eastern Temperate Forests have proven to be a very resilient region; these great forests still provide habitat for many birds, animals, reptiles, amphibians, and insects, as well as recreational and economic benefits for the people of the region.[44]

Climate

The Eastern Temperate Forest region has a wide range of fluctuating temperatures dependent on time of year. In this region, there are four distinct seasons- winter, spring, summer, and fall. This seasonal variation is caused by exposure to both warm and cold air masses due to the biomes mid-latitude positioning between the polar regions and the tropics and is reflected in both the seasonal temperatures and precipitation levels. The highest temperatures, averaging 21 °C, occur during the summer months of July and August, and the lowest temperatures, averaging 0 °C, occur during the winter months of December, January, and February. The year-round average temperature within the region is 10 °C.[45] Levels of precipitation vary with the seasons as well, with the highest levels of precipitation, averaging 95 mm/month, occurring in May and August, and the lowest, averaging 60 mm/month, occurring in June and the winter months of January, February, March, and December.[46] The Eastern Temperate Forest region can thus be described as “warm, humid, and temperate” with abundant levels of precipitation year round.

There are many global patterns that affect and contribute to the climate of the Eastern Temperate Forest region, such as global ocean currents, El Nino, La Nina, the Gulf Stream current, and global air circulation patterns. El Niño, caused by warmer sea-surface temperatures in the Pacific Ocean, can lead to “wet winters” and warm episodes occurring between the months of December and February in the southeastern region of the United States Eastern Temperate Forest.[47] La Niña is caused by cooler than normal sea-surface temperatures in the central and eastern tropical Pacific ocean, it leads to drier than normal conditions in the winter months in the Southeast region of the Eastern Temperate Forest.[48] The global ocean current that effects the Eastern Temperate Forest most is the Gulf Stream current which brings a warm flow of water from South to North along the eastern coast of North America in the Atlantic Ocean, it keeps temperatures in this region relatively warm. The winds that have the greatest effect on the climate of the region are the prevailing westerlies and the tropical easterlies. The prevailing westerlies, caused by the Coriolis Effect, explain why most major events that occur in North America come from the west and proceed east, which is where the majority of the Eastern Temperate Forest is located.[49]

Dominant plant and animal species

Fall foliage of the Eastern Temperate Forests

The Eastern Temperate Forest Ecoregion has favorable growing conditions for a number of plant species, the dominant being large, broadleaf, deciduous trees.[44] Before the arrival of Europeans, this area was almost completely forested. After their arrival a few centuries ago, much of these forests had been cleared for timber and to make way for cropland. In more recent time, however, these open areas have been abandoned and are slowly returning to forest. Of the many plant species that inhabit the Eastern Temperate Forests today, those of the oak (Quercus), beech (Fagus), maple (Acer), basswood (Tilia), and pine (Pinus) genera are the most characteristic and defining of this ecoregion.[50] These plants can be broken down into several main communities: northern hardwood, beech-maple, maple-basswood, mixed mesophytic, oak-hickory, and southern mixed hardwood forests. With the exception of Pinus, all of these species are angiosperms, meaning that they produce flowers and fruits, an important food source to many animals who inhabit the region. The flowers of angiosperms provide nectar, their leaves are important vegetable matter for herbivores, and their seeds are rich in fat and protein rich that allow many animals to fatten up for their winter hibernation. The trees of the Eastern Temperate Forests provide food, shelter, and a suitable habitat for countless species of both flora and fauna; they yield lumber, fuel, recreation, and aesthetic enjoyment to not only the people who live in this region, but also those who visit and enjoy products produced from the resources gleaned from these vast forests.

Arboreal species are widely found in the region due to the high density of tree cover, providing a suitable habitat and food source for the animals; this includes birds and many ground squirrels. Migratory songbirds are common in the eastern temperate forests once the canopy opens up in the spring. Mammals that are native to the eastern forests are white-tailed deer, black bears, ground squirrels (gray squirrels and chipmunks), as well as red and grey foxes. Bird species include, the black-throated warbler, piping plover, and the yellow- breasted chat. Amphibious species that are common to the region are the American toad and the box turtle.

White-tailed deer populations are very large across the eastern US, making it both a dominant and defining species. The white-tailed deer competes with other herbivores for limited food resources directly affecting the ecosystem, as well as indirectly affecting the area by altering habitats for small vertebrates and mammals. According to the Virginia Journal of Science’s research on white-tailed deer, deer are grazers primarily, feeding on the leaves of shrubs and such; however in the winter months they are found browsing the woody stems of shrubs and saplings. White-tailed deer have four stomachs, each with their own specific digestive action. The complex breaking down of food allows the deer to each woody plants and other things that most animals cannot digest. Areas with high deer populations, will see a dramatic shift in forest cover because small saplings and shrubs growth with be retarded on hindered due to their browsing habits. White tailed deer are polygamous; in the northern parts of the region they will mate in November and for more southern dwelling populations mating occurs in January. A female will give birth to one to three fawns, after a 6-month gestation period. After about 3 months, the young will leave their parents. White tailed deer typically live about three years but can live up to 15 years. White-tailed deer exemplify a “k-selection” species. They have long gestation periods, can reproduce more than once in a lifetime and are only a few offspring are produced at once.

Endangered species

The United States has more endangered species than all of the other continents combined, the Eastern Temperate Forest’s endangered and threatened species make up a little less than a quarter of that number.[51] Endangered and threatened mammals (but not limited to) include, the Louisiana black bear, the red wolf, the Key deer, the eastern puma (cougar) the West Indian manatee, the North Atlantic right whale, the Mississippi sandhill crane, the piping plover, and the leatherback sea turtle. Endangered and threatened flowering/non-flowering plants include, the Virginia round-leaf birch, the Tennessee yellow-eyed grass, the Michaux's sumac, the Florida torreya and the Louisiana quillwort, among many others. The region is also home to the only two endangered lichen species, rock gnome lichen and Florida perforate reindeer lichen.[52][53]

Piping plover, Charadrius melodus

The piping plover is a bird that has been on the endangered species list since 1985 in the Great Lakes watershed (including: NY, PA, IL, MI, and WI.) This species nearly became extinct after over hunting in the 19th and early 20th century due to use of feathers for fashion hats.[54] Current potential sources of endangerment include, the development of coastlines for recreation, and detrimental material washing up to shore.[55] The management of the habitat sites, closing off sections of the beach where birds are nesting, creation of a mimic habitat, predation management, restriction of beach vehicles, and vegetation control are current conservation efforts being enforced.[56]

The Louisiana quillwort has been on the list of endangered species since 1992; contrary to its name it is only now found in MI and AL.[57] Threats to this species include, pollution (herbicides and chemicals), construction in proximity to stream, vehicle traffic on or near stream, changes in flow rate and erosion (these two factors most likely caused from climate change.)[58] Conservation efforts being enforces are, updates to where the population status is, permanently protecting existing habitats (through local and federal levels), look for potential populations that are not accounted for, preserve the genetic stock of the species remaining, and more in-depth habitat studies leading to population fluctuation.[57]

Geology, topography, and soils

The Appalachian Mountains are a main topic of research, regarding the geology of the surrounding area. They formed when the ancestral continents of North America and Africa collided together and are about 480 million years old. The folded and thrust faulted igneous rocks, marine sedimentary rock and rocks that look like that of the ancient ocean floor, reveal that they got pushed up during plate collisions.[59] Ice ages, during the Pleistocene epoch (after the Appalachians formed), contributed a great deal to the current appearance of the surrounding area. Surfaces that were once covered by ice were eroded and smoothed out during glacier movement. Therefore, the Appalachians used to be much taller when they formed, than they are today.[59] Glaciers also deposited parent materials of the underlying bedrocks, which contribute to the formation of soils later on.

There are very clear soil horizons, when looking at a cross section of this land. These are labeled and described (see Figure 2) as: O: organic matter, A: fine particles of organic matter and mineral material, B: material layer where most nutrients accumulate, C: parent material, and R: bedrock1. The U.S. Soil Taxonomy classifies Inceptisols, Mollisols, and Spodosols as good soils that can support temperate forests that like mature soils that can support deep root systems1. Different levels of nitrogen also have a big effect on a soils capability of supporting life. The presence of too much nitrogen can cause declines in species richness and abundance.[43] The types of vegetation that exist in the Appalachian area heavily rely on the existing soil types and amount of nutrients available.[60]

Traditional and emerging natural resources

The Eastern Temperate region has a vast wealth of natural resources that are utilized by people. The two most common traditional resources include timber and coal. Timber specifically hardwoods, which make up the majority of timber from this region, are utilized widely for furniture production. In 1997 there was about 6 billion dollars worth of solid wood exports with 36% coming from the eastern United States.[61] Coal is the other major traditional resource of the region. Coal is found on the western slopes of the Appalachian mountain range as well as in parts of Illinois and Indiana. In 2003 U.S. coal production was about 1.07 billion short tons and while not all of this comes from the eastern region a large portion of it does as 6 of the top 10 coal producing states are from within this region as of 2012.[62][63]

Natural gas and oil from hydraulic fracturing is an interesting relatively new emerging resource from the region. “Fracking” as it is commonly known involves sending pressurized water or sand into shale deposits into order to open up more cracks for which natural gas and oil can flow through, into the pipes and out of the ground. There were 8.982 drills as of 2011 in Pennsylvania alone that operated under hydraulic fracturing.[64] Though this is an intriguing emerging resource for the region it also is extremely controversial as oil and gas from the “fracking” process can sometimes seep into ground water and contaminate it.

Current environmental threats/ Impact of climate change

There are three major current threats to the Eastern Temperate Forest. These include agriculture, invasive species and overpopulation/urbanization. A major use of land in the eastern temperate forest is for agricultural purposes due to the rich soils which are easily converted to farmland. Pesticides in particular threaten the health of the eastern temperate forest region because they are used in massive quantities for agricultural production but are also widely popular in homes, businesses, schools, hospitals, and parks to maintain lawns or fields.

Another problem with no easy solution that faces the eastern temperate forest are non-native invasive species like the emerald ash borer. The emerald ash borer is thought to have been introduced to Michigan from China about 15 years ago.[65] The adult beetles target ash trees as places to lay their eggs, when the larvae hatch they bore through the bark and kill the tree. The health of the ash population is of major concern because they provide habitat for many wildlife species and edible seeds for birds, mammals, and insects.

The biggest threat besides climate change to the eastern temperate forest is its high density of human inhabitants. According to the Commission for Environmental Cooperation approximately 160 million people or over 40 percent of North America’s population, lives within the ecological region of the eastern temperate forest12. Such population density can be attributed to the concentration of the continents economic, political, and industrial power in this region. Major cities and sprawling suburban communities between them have drastically changed the regions landscape and fragmented local habitat. Roads and highways divide habitat and limit migration while urbanization and deforestation completely eliminate suitable habitat and food sources. Studies conducted by Kansas State University have shown that fragmentation can decrease population productivity by isolating populations, crowding species, and causing edge effect.[66]

As the planet faces more intense and severe impacts of climate changes, each element of the eastern temperate region will be affected, from flora and fauna, to soil and water. Vegetation mortality, soil content, species existence, water levels, and overall functionality of the Eco region will continue to change and be altered as global warming and the concentration of greenhouse gases increases. Climate change correlates with disturbances such as insect outbreaks, harsh weather, and susceptibility of forests to invasive species, all of which can impact the functions of a forest. Insect breakouts can completely destroy an entire habitat within one season. With increased drought and higher temperatures, the weakened forest can suffer from multiple tree species loss, along with the loss of animals and creatures that serve vital predatory roles within the ecosystem. Plants that are considered to be moist-forest herbs, such as Cohoosh and Clintonia, are threatened by the lack of available water that is vital to their survival. As climate change more rapidly progresses, temperature increases will impact the length of the growing season. Tree species growing range will shift to adapt to the new climates, typically moving to higher altitudes or more northern regions. For example, mountaintop tree species like the red spruce will potentially die out because there is no higher altitude that is available for relocation. In addition to the northern migration, southern species such as the red oak have expanded their territories. Therefore, as species that thrive in the lower areas of the region are expanding into a greater space, they are beginning to compete for resources and nutrients with pre-existing native species. This can be said for many bird species as well. A study conducted by the USDA Forest Service confirms that 27 out of 38 bird species that inhabit eastern temperate forests, have expanded their territory further north. The water cycle is also incredibly susceptible to the impacts of climate change. The water quality and ecosystems within lakes, streams, and rivers are all greatly affected by the alterations of precipitation patterns. Increases in runoff potentially increase the chemical contents within the water, such as nitrate and acid pulses. Aquatic species are stressed by not only the warmer temperatures themselves, but also the low flows and timing of ice-outs and thaws. Such factors affect oxygenation cycles, productive cycles, and reproductive cycles. Seeing as though the Eastern Temperate Forest region is considered to be a significant evolutionary zone for fauna, the impacts of climate change can substantially alter the balances and chains of not only the Ecoregion, but the planet as well.

Level II (Sub) Ecoregions

The Eastern Temperate Forest ecoregion is divided into five Level II ecoregions: Mixed Wood plains, Central USA plains, Southeastern USA plains, Ozark and Ouachita- Appalachian Forests, and Mississippi Alluvial and Southeastern Coastal Plains.

The land formation of the 490,590 square kilometres (189,420 sq mi) area of the Mixed Wood plains is predominantly plains, with some hills, and the bodies of water are many small lakes. The surface materials of the region are moraines and lacustrine and the soil composition includes forest soils and fine textured soils. The mean annual precipitation of the area ranges from 720–1,200 millimetres (28–47 in) and the mean annual temperature generally varies between 4–10 °C.[43] In this area, human activity includes fruit and dairy agriculture, major urban areas, and some forestry and tourism attractions. The most prominent wildlife observed are white tailed deer, moose, and the grey squirrel, and vegetation includes a wide range of trees such as oak, hickory, maple, beech, and some pine and basswood species.

The second sub-ecoregion is the Central USA Plains, anarea of 253,665 square kilometres (97,941 sq mi), that has a landform of smooth plains. The majority of this region’s surface material is moraine with some lacustrine, and the soil consists of calcium enriched prairie soils and forest soils on moraine. The climate consists of a mean annual precipitation of 760–1,100 mm and average temperatures varying from 7–13 °C.[43] Human activities largely include corn and soybean agriculture, major urban areas, and local dairy operations. Vegetation is mostly prairie type in the west, but also includes oak, hickory, elm, ash, beech, and maple. White tailed deer, cottontail rabbits, and grey squirrels are the most commonly represented wildlife.

The Southeastern USA plains are the third Level II ecoregion and have a land area of 946,770 square kilometres (365,550 sq mi). The majority of this land consists of irregular plains with low hills, which is made up of predominantly residuum and some loess on weakly developed soils. The climate of this region is an annual precipitation of 1,000–1,600 millimetres (39–63 in) and average temperatures of 13−19 °C.[43] Human activities include predominantly forestry with tobacco, hog, and cotton agriculture, along with major urban areas. There is a wide array of wildlife which can include white-tailed deer, grey squirrels, armadillos, wild turkeys, northern cardinals, and mockingbirds. The vegetation of the area is less diverse and includes oak, hickory, loblolly, and shortleaf pines.

The Ozark and Ouachita-Appalachian Forests region is an area mostly consisting of hills and low mountains, with some wild valleys that make up the 518,690 square kilometres (200,270 sq mi) of land. This land is primarily residuum and colluvium matter on weakly developed soils and is put to use by humans through forestry, coal mining, some local agriculture, and tourism operations. The temperature averages around 17–18 °C annually and precipitation can be anywhere from 1,000–2,000 millimetres (39–79 in), which provides a suitable environment for mixed oaks and hickory, white pine, birch, beech, maple, and hemlock trees.[43] In this environment, black bears, white tailed deer, chipmunks, and wild turkeys are commonly found

The final of the five Level II ecoregions in the Eastern Temperate Forest is Mississippi Alluvial and Southeastern Coastal Plains. The 368,720 square kilometres (142,360 sq mi) of land in this region is home to a very vast amount of organisms including animals such as white-tailed deer, opossums, armadillos, American alligators, mockingbirds, and egrets, along with varying vegetation from bottomland forests (ash, oak, tupelo, bald cypress) and southern mixed forests (beech, sweet gum, magnolias, oaks, pine, saw palmetto). The climate of 13−27 °C and precipitation varying between 1,100–1,800 millimetres (43–71 in) annually provides adequate conditions for forestry, citrus, soybean, and cotton agriculture, fishing, and tourism.[43]

Mixed Wood Plains

Central USA Plains

Southeastern USA Plains

Ozark, Ouachita-Appalachian Forests

Mississippi Alluvial and Southeast USA Coastal Plains

Tropical Wet Forests

Tropical Wet Forest canopy

The Tropical Wet Forests ecoregion in North America includes the southern tip of the Florida Peninsula in the United States; within Mexico, the Gulf Coastal Plain, the western and southern part of the Pacific Coastal Plain, most of the Yucatán Peninsula and the lowlands of the Chiapas Sierra Madre, which continue south to Central and South America.[67]

Climate

The tropical wet forests of North America have an average year round temperatures between 68−78.8 °F. Thus, frost does not occur under these conditions.[68] The temperatures remain fairly uniform throughout the year; therefore there is not a change of seasons. There is also no dry season, as all months experience precipitation. The average annual precipitation ranges from eight to fourteen feet per year. The high levels of precipitation usually cause poor soil quality because soluble nutrients are lost due to the nutrient leaching process. The average humidity is between 77−88%. Nine out of twelve months of the year are considered “wet” months. The overall climate of the tropical wet forests ecoregion can best be described as humid, warm, and wet. George Hadley, a scientist who researched during the 18th century suggested that warm tropical air rises and moves north. Colder high latitude air flows south nearer to the Earth’s surface where it displaces the former air. Hadley’s explanation is highly accepted and still expanded upon today. The warm, moist air in tropical wet forests is unstable; meaning as soon as the air rises it becomes saturated.[69] In addition, there are large amounts of heat, or convection occurring at the same time. The vast bulk of vertical movement of air occurs in the Hadley cell and thus provides an explanation for the global circulation patterns.[70]

The direction of the wind at various levels of the atmosphere determines local climate and can result in severe weather patterns. For example, in an El Nino winter the presence of warm water in the eastern Pacific Ocean can shift the position of a subtropical jet stream. This results in heavy rainfall in the tropical wet forest ecoregion. Also, in a warming climate the Hadley cell could increase the severity of climate. As a result, the ecoregion may become hotter and wetter for longer periods of time.[71]

Hydrology

Hydrology in Tropical Wet Rainforests keeps the flow of water throughout the ecosystem, which nourishes plants, keeps local aquifers and rivers active and the environment in the area functioning.[72] The watershed and basin pattern have three major contexts; first, low-gradient drainage, second, typically high ground water table, and third, extensive drainage canal network. This idea applies to all areas, but have unique outcomes in Tropical Wet Rain Forests in North America specifically. Tropical Wet Rainforests have an excess of vegetation, compared to many other ecoregion types such as savannahs, and therefore have a much slower drainage rate than other ecosystems.[73] When an ecosystem has a high ground water table it separates the time between drainage and absorption of water in an area. It helps organisms to absorb nutrients, while also slowly filling up aquifers in the ecosystem. So primarily the down time between rainfall and drainage is slowed due to vegetation and climate, but now due to the vastness of the ecosystem, the drainage canal network is large and water can fall in one place, and end up in many other places at the end of the draining process.[73]

Geology, topography, and soil

Wet tropical forests in North America span from sea level to an altitude of 1,000 metres (3,300 ft). They have particular geologic, topographic and soil conditions that characterize them. These characteristics influence biotic structures and relationships and have contributed to the high biodiversity of the ecoregion.

The geology of these forests is primarily composed of folded and metamorphic hills, which are covered by a thin layer of alluvium (loose sediments and soil).[74] The bedrock is sedimentary and rich in silica and dates back to the Precenozoic periods when much of the region was underwater.[75]

The topography of wet tropical forests includes valleys, hills, ridges and low mountains. Depending on elevation and the location of such features, areas as referred to as either lowland or highland.[76] These elevation and topographical changes allow for a higher variety of specialized conditions, which increases habitat. The inclination changes (or slope) of the forest floor greatly affects water drainage and the leaching of nutrients, and valleys can have an accumulation of sediments and nutrients versus plateaus and ridges.[77] But the most important topographic characteristic is the extensive network of rivers that weave across the landscape, acting as a drainage system to the forest that can receive upwards of 250 inches of rain a year.[78]

Tropical Forest river

The soils in wet tropical forests are some of the most diverse of any region, and they are the cause for many biological adaptations. There is a combination of highly weathered and leached soils as well as less weathered alluvial soils, categorized as “oxisols” and “ultisols”.[79] Their pH can vary immensely, sometimes being as acidic as 4.0. The soils are generally shallow, often only a few inches deep.

The soil is produced from decomposing organic matter and the breakdown of bedrock, but is generally poor in nutrients; most nutrients are found as superficial detritus and within the living components of the ecosystem. There are multiple reasons for why the soil is generally very poor in nutrients. Firstly, the warm and humid climate allows for a rapid decomposition rate, meaning that nutrients do not stay present in or on top of the soil for long before being absorbed by the biota. Secondly, the acidity of the soil, caused by the few cation exchange sites to be occupied by hydrogen ions, increases the loss of minerals such as iron, aluminium oxides and phosphorus. Thirdly, leaching, which is the continuous downward movement and loss of solutes and minerals from the soil, happens regularly due to the heavy rainfall.[80] You wouldn’t be able to tell that the soil is poor from the lush, dense vegetation in these wet tropical forests; but shortly after an area of forest is cleared for agriculture (usually through slash-and-burn) the small amount of nutrients wash away and the soil becomes infertile.[81]

The ecosystems have developed highly specialized ways of mitigating effects such as leaching, but these functions are fragile, and need to be protected. This includes tree adaptations such as buttress roots and thick root mats that grow laterally along the forest floor. These adaptations mitigate nutrient loss by capturing the nutrients in falling detritus, before the nutrients are absorbed and decomposed into the soil, and lost from leaching by the heavy rains.[82] The geologic, topographic and soil changes across wet tropical forest ecosystems has contributed to the astonishing biodiversity in biota we see today.

Buttress roots

Plant communities

The plant communities of the tropical wet forest are the most diverse, abundant, and lush plant life in the world. The plants define the tropical wet forest by contributing to ecosystem functions, such as producing nourished rainfall and storing atmospheric carbon. Tropical wet forests are characterized by the complex, physical structure of the ecosystem. There are many layers of plant communities, though they are rarely visible from the ground. Shrubs and creepers fill the forest floor with saplings dispersed throughout. Large trees hold their full crowns in the canopy, prohibiting sunlight to plants below. Beneath the canopy of trees lies a network of stout branches, thick limbs, and climbers. Sometimes even above these trees, the largest of canopies fill the sky like individual islands.[83]

Large trees, such as the pacque, allspice, and breadnut tree, provide habitat for most animal species and other plant species. The leaves are usually oval, thick, and waxy with pointed drip-tips to alleviate water collection. Roots are often buttressed (flaring from above ground), radiated across the forest floor, or stilted as prop roots. Lichens, orchids, and mosses cover the trunks of trees, retaining moisture and hosting small invertebrates. Most tropical trees have large, colorful, fragrant blossoms and plump fruits, perfect feeding for animals and insects.[83] Climbers, hemiepiphytes, and epiphytes are the major groups of non-tree species, although they tend to inhabit trees. Climbers provide a road system in canopies for motile animals.[84] Vines are large in biomass and are an essential food source to many fauna. Hemiepiphytes have the most unusual growth forms and are parasitic to larger trees. Epiphytes claim space on a branch and set roots, trap minimal soil, and photosynthesize. They adhere tightly to the bark of trees but, are not internally parasitic. As rain forests become drier and more disturbed, these native species become more rare. The loss of these plant communities severely impacts the world, in regard to increase of carbon dioxide, high floods, and impure water.

Key animal species

Jaguar-Biouniverzoo

The two main keystone species of the Tropical Wet Forest ecoregion are the American crocodile and the Mexican jaguar. They are both top predators and influence the population of their pray. American crocodiles create habitat for many creatures through their water holes and the paths they create. Their diet consists of fish, snails, birds, frogs, and mammals that come to the water’s edge.[85] Males can grow up to 15 feet long and weigh up to 2,000 pounds while females range from 8–13 feet. Their average life span is around 45 years. Females lay a clutch between 20−60 eggs which hatch after an average of 85 days. The mother leaves the young to fend for themselves after a few days.[86] The jaguar is the third largest cat in the world and the largest in North America. It is between 5 and 8 feet, nose to tail, and weighs between 140 and 300 pounds. Their average lifespan in the wild is 12–16 years while in captivity it ranges from 20–27 years. They have been observed to prey on around 85 different species, the most common of which are terrestrial mammals, they prefer giant anteaters, capybaras.[87] Females become sexually mature around 2–3 years while males become sexually mature around 3–4 years. They have a gestation period about 100 days and give birth to an average litter of 2 cubs. The cubs are able to open their eyes after about 8 days and are able to walk 10 days after that. They stay with their mother for a year and half.[88]

Natural resources

Tropical wet forests are known for their wide diversity of natural resources. Historically, the primary harvestable products they produce are from plants including exotic lumber such as mahogany, red cedar, and also gum tree for rubber. Other plants that can be utilized from this region include common food items such as bananas, cacao, oranges, coffee, sesame, alfalfa, cotton, and a variety of peppers.

Following Spanish and English colonization of the area there was a shift towards larger scaled agriculture plantations. With these plantations came increased production of sugar cane, beans, pineapples, and chiles as well as an increase in harvesting of precious lumbers. This trend continued largely up into the 1960s when large swaths of land were cleared to make room for cattle ranches.

Consecutively came the influx from the petrochemical industry to extract the vast reservoirs of oil that exist underground. This new development led to even larger portions of land being cleared for oil drilling sites and roads compounding the existing problem of deforestation in the region.

One ray of hope for the future of natural resource procurement in tropical wet forests is the search for medicinally valuable plant secondary compounds. Plants that contain compounds that can treat ailments ranging from analgesics, antibiotics, heart drugs, enzymes, hormones, diuretics, anti-parasitics, denitifrices, laxatives, dysentery treatments, anti-coagulants and hundreds more exist and could prove to be a valuable economically viable as well as sustainable alternative to current resources being utilized in the area.

Environmental threats

Deforestation is the main threat to the North Americans tropical wet forests and has devastating consequences. Deforestation causes habitat loss and habitat fragmentation which have drastic effects on biodiversity.[89] Deforestation of tropical wet forests has caused many native species to become endangered or extinct at an alarming rate. The Tropical Wet Forests around the global are being deforested at an alarming rate. For example, some counties like Florida have lost 50%[90] of their tropical wet forest habitat and Costa Rica has lost about 90%.[91]

Protection of the tropical wet forests we have left is very important for its continued existence. Many Reserves have been created in an attempt to protect the little we have left of these forests. Some examples of this in the United States are Florida's Everglades National Park and the Big Cypress National Preserve.

Another important tool for the continued existence of tropical wet forests is Restoration. There have been successful restoration projects of a tropical wet forest with native species in Costa Rica. These restoration projects have been shown to significantly improve the native animal and plant species survival.[92] It is necessary for good management plans to be developed if we are to use tropical wet forests sustainably.

Endangered species, threats, and conservation

Harpy eagle

The IUCN Red List has 65,521 species listed as threatened in the tropical wet forests.[93] The Harpia harpyja, harpy eagle is one threatened species in the tropical wet forests, they are the largest neotropical bird of prey, nest in the tallest trees, prey mostly on animals that live in trees, lay between 1−2 eggs but only allowing 1 egg to hatch, reproduce every 2–4 years, and reaches sexual maturity between the ages of 4 and 5.[94][95] The harpy eagle is suffering because of slow reproductive rates, hunting, food competition, fragmentation, and habitat destruction.[94] There are many orchid species that are threatened in the tropical wet forests. Orchids are a smart plant that manipulate other species into pollinating them, and once pollinated they produce seeds that are eventually released in hopes to be carried to a specific type of fungi (depending on the orchid) where it will attach for mycorrhizal symbioses, and then bloom after a few years or decades depending on the environment and species.[96][97][98] Many orchid species are suffering because of overharvesting, burning, clearing, and development.[99] Many efforts are being done to help save both species. Spreading knowledge (educating), creating reserves, and coming up with alternatives are the top three actions being done to conserve both species.[100][101]

Effects of climate change

Over the last 100 years the Earth's temperature has increased 0.6 degrees Celsius and it is predicted to increase an additional 3.5 degrees over the next century.[102] Tropical wet forests account for only 6% of earth's land surface yet are responsible for 40% of earth’s oxygen production.[103] Any type of change to this system can prove to have significant detrimental effects in terms of global oxygen availability. In addition, due to the sensitivity and fragile interactions between organisms and the atmosphere, ecosystem services such as carbon sequestration rates, will experience even larger adverse effects.

Amounts of precipitation and moisture availability are also areas of concern. Global precipitation is expected to rise two-fold in tropical areas. This will cause shifts in vegetation as moist forest species expand into new areas of moisture. Increasing atmospheric emissions also plays an integral role in precipitation patterns.[104] Annual rainfall is projected to decrease across the Everglades National Park causing a hydrologic change across the entire region. Dry vegetative communities will outnumber hydric vegetative communities in this particular area.[105]

Furthermore, a one degree increase in atmospheric temperature is the result from a doubling of atmospheric CO2. Effects of this increase on forest soil temperature include reduced tree growth and higher decomposition rates of deep soil organic matter.[106] Ultimately, as the forests become a larger carbon source to the atmosphere, ecosystem services cease to function, and the delicate balance found in the tropics is disrupted, the climate warming cycle intensifies.

The iconic ecosystems of the region

An iconic ecosystem of this region is the complex interaction and the variety of biota along with fairly consistent abiotic factors; even though this eco region covers roughly seven percent of the earth's surface, its tree community is the most diverse on the planet.[107] It would not be unusual to have 100 different tree species coexisting within a one-hectare plot.[108] The tree community contains many broad-leafed evergreen trees, which form a high canopy (30–40 meters) above the ground.[109] The understory contains a variety of more shade tolerant plants, which is a necessity for survival due to the thick canopy above. The vegetation is "spatially heterogeneous".[110] This plant community survives in nutrient-poor soils conditions making disturbances (such as deforestation) to have greater impacts because regeneration of the forest takes much longer. Tributaries and river systems have formed from the large amount of rainfall and typically carry a lot of sediments, but increase water demands and the construction of dams can further alter and strain these ecosystems.[111]

Plain and Hills of the Yucatan Peninsula

Sierra Los Tuxtlas

Everglades

Western Pacific Plain and Hills

Coastal Plain and Hills of Soconusco

References

Tropical rain forests. (n.d.). Retrieved from http://www.marietta.edu/~biol/biomes/troprain.htm

North American Deserts

Introduction

The North American Deserts include both cold and hot deserts, which supply a variety of climates. Due to this fact, they are often used for agricultural, business, or petroleum purposes. These factors have been taking a toll on the desert climate, organisms, and landscape. These deserts are the Mojave, Sonoran, Chihuahuan and the Great Basin.

Plant communities

The North American Deserts are home to a variety of plant species. These plants are categorized as either xerophytes, adapted to the arid conditions of the desert, or phreatophytes, which are plants with very deep roots that are dependent on a permanent water supply and survive by tapping groundwater.[112]

Agave lechuguilla

These species have come to possess several adaptations that allow them to survive and thrive in these dry and harsh conditions. One of the most common of these species is the barrel cactus (Echinocactus and Ferocactus). This plant was important to Native Americans and served a number of purposes, including use for food and water and creating fish hooks from the spines. Another common species is the Shin Digger (Agave lechuguilla).

With its shallow roots, it is able to take in a large quantity of water and store it in its pedals for extended periods of time.[113] The Ocotillo (Fouquieria splendens) is another plant frequently found in this area, which is a very uniquely shaped plant. Because of this, it is often referred to as a “vine cactus.” This plant has an adaptive ability to photosynthesize during very dry conditions and gather large quantities of water when it is available.[114] The Great Basin is also home to the oldest species in the world, the bristlecone pine (Pinus longaeva). Its needles allow it to retain water and use very little of it during its lifetime. It is able to grow on exposed rocky surfaces in higher elevations about forested areas. With these advantages come some drawbacks, including its very slow growth rate, which leaves it vulnerable to being out-competed by faster growing trees.[115]

Dominant/characteristic species

There are a variety of mammals that define the North American Deserts such as the bighorn sheep, mule deer, white-tailed deer, ground squirrel, coyote, prairie dog, cottontail rabbit, desert packrat, and mountain lion. There are a number of birds and reptiles that thrive in these ecosystems as well. The cactus wren, Gambel's quail, burrowing owl, red-tailed hawk, hummingbird, desert tortoise, and vulture to name a few.

An example of a keystone species in the North American deserts would be the coyote or mountain lion. These two predators can control the population and distribution of a large number of prey species. A single mountain lion can roam an area of hundreds of kilometers, in which deer, rabbits, and bird species are partly controlled by a predator of this caliber. They will change the feeding behavior or where they decide to nest or burrow is largely a reaction to the mountain lions activity. Another example, such as the hummingbird, new plants or animals could also come into the habitat and push out native species. In the Sonoran Desert, the hummingbird pollinates many native species of cactus and other plants. The hummingbirds in this region, such as the Costa's hummingbird, have evolved to have very long beaks and tongues that wrap around the skull in order to reach the nectar for that sweet sugar staple.

Topography, geology, and soils

The Great Basin Desert is the only Cold desert, bordered by the Rocky Mountain range to the east, and the Sierra Nevada – Cascade to the west. The northernmost part of the desert lies 2,000 metres (6,600 ft) above sea level, and due to high summer temperatures, not all of the fallen precipitation is fully absorbed into the soil, resulting in a high sodium concentration.[116] In other areas, mountain erosion has caused deep soils of fine particles, which allows for standing lakes.

The Mojave lies between the Sonoran (south) and the Great Basin (north). Here, soil is shallow, rocky, and dry. The average elevation is between 3,000–6,000 feet (910–1,830 m) above sea level. The Mojave has several mountain rage boundaries, the Garlock and the San Andres. They are made up of the two largest faults in the state of California.

The Sonoran is referred to as the Base and Range geologic province. Here, the Mogollon rim exists of sandstone and limestone piled over millions of years. The basin and valley were made from volcanic eruption 40 million years ago, and the underlying rock is made primarily of cretaceous (aged granites).

The Chihuahuan desert is made up of calcareous soils that have a high pH and calcium concentration. The soil is thin, sandy, and gravel like, and rests atop deep layers of limestone. Higher elevations allow water to sink deeper into soils that are made of finer particles, and deep sedimentary fans exist. Limestone beds show that this desert was at one point fully submerged beneath the sea. This desert features elevations ranging from 1,200 metres (3,900 ft) above sea level, to 350 metres (1,150 ft) below.

Hydrology

There are common patterns of hydrological cycles throughout the North American Deserts, but specifics of times and source of water range. All four deserts rely on rivers, precipitation, and underground aquifers to replenish their water supply.[117] The water in the North American desert is mainly freshwater. There is an ephemeral flow of underground water during the wet seasons that slows during each sub-desert’s dry season.[118] Oases form in all four deserts when the groundwater reaches the surface and pools in the hollows of the desert basins.[119] Being surrounded by mountains provides a rain shadow effect that contributes to the dry climate and creates the desert ecosystem.[120] All four deserts experience times of drought and times of intense precipitation.[121] The Colorado River flows through the Mojave, Great Basin, and Sonoran desert .[117]

But, differences in seasonal rain create the differing hydrological cycles. The Great Basin receives most its rainfall in the winter.[117] This leads to creation of playa lakes in the spring, as the snowfall melts and flows down surrounding mountains.[122] The Sonoran Desert has a bimodal precipitation pattern that includes winter storms and summer monsoons, which help sustain flora.[123] The Chihuahuan Desert relies primarily on its intense summer monsoon for water. During the summer is when the area sees the accumulation of playa lakes.[119] They may all have similar characteristics, but the difference in location and evaluation attribute to the diversity of their hydrological sources and cycles. Although the Northern American Deserts are characteristically dry, they still contain the water necessary to fuel their ecosystem and sustain the life of humans, animals, and plants alike.

Climate

North American deserts can be categorized by climate categories of hot and cold deserts. The cold deserts include the Thompson Okanagan Plateau, Columbian Plateau, Northern and Central Basins, Colorado Plateaus, and the Snake River Plane. All of these North American Deserts are included in the cold category, which indicates that they have a dry mid-latitude steppe or desert climate. These areas are impacted by their interior position within the continent leading to broader temperature ranges and considerable rainfall. More specifically, these areas are impacted by the rain shadow created by neighboring mountain ranges, acting as a barrier to westerly flowing air carrying moisture. All of these cold deserts experience about 100–300 mm of precipitation in a year indicating a semi-arid climate.

The warm deserts of North America include The Mojave Basin and Range, the Sonoran desert, and the Chihuahuan desert. These areas have a tropical desert climate, and are known as the hottest and driest place on the continent. This is due to the continental interior location on the leeward side of mountains, with constant subtropical high pressures. The high temperatures throughout the year are due to the high percentage of sunshine caused by high sun angles. Increased distance from a body of water leads to a lack of clouds, which is associated with much cooler nighttime temperatures because all the heat of the day is lost. The only source of water in the warm deserts is an oasis; this creates an arid climate in the area distinguishable by the lack of moisture in the soil due to annual precipitation being less than half of the annual potential evapotranspiration.

Ecological concerns

The North American Desert biome is facing a variety of ecological threats. Human disturbance poses the number one concern to this fragile ecosystem. The Sonoran desert contains the two large cities of Tucson and Phoenix, Arizona, which contain over 3 million people.[124] These dense human populations deplete the water table of the entire desert and are sending the desert towards desertification. Also, the Chihuahuan desert is seeing the effects of agricultural expansions, invasive species, illegal poaching, and extractions of resources such as salt, lime, and sand.[125] These activities in the desert lead to eventual desertification and a loss of overall biodiversity. A number of organizations such as the United States Nature Conservancy and the World Wildlife Fund have begun working together to conserve the threatened desert ecosystem. The less heavily populated areas of the desert are being sought out and conserved in order to prevent future human habitation and disturbance.[124] Also, several organizations are now monitoring the use and health of the Rio Grande system located in the Chihuahuan desert, while also building new low tech water treatment facilities that will help to prevent overall water table depletion. The World Wildlife Fund is replanting disturbed, upland vegetation in order to retain species habitat and biodiversity. These measures are helping to protect and preserve the four North American Desert ecosystems.

Endangered species

The giant kangaroo rat is one of the most peculiar looking rodents around. The Dipodomys ingens can grow up to 34.7 centimeters in length and have a tail of up to 19.8 centimeters long. They can weigh up to 180 grams. It is mainly found in the San Joaquin Valley in California. The giant kangaroo rat forages for food from sunset to sunrise. Its diet consists mainly of seeds, that are sun dried and some greenery. They store food in their cheeks until they bring it back to their burrow systems, where they store food that could last them up to 2 years of drought. The giant kangaroo rats develop rather quickly. Depending on the environmental conditions, they can reproduce after about 5 months. Their litter size varies but averages about 3.75 offspring.These rodents are rather resilient when it comes to surviving under natural conditions, such as drought and low plant productivity. However, when the human factor is introduced, they have a much less successful survival rate. Aqueducts and other water projects started crisscrossing the giant kangaroo rat habitat. Agriculture moved in because of the new water routes and suddenly the habitat of many species became agricultural land.[126] Kangaroo rats became a pest for farmers and rodenticide-treated grain became common practice which took out another chunk of their population.

Nichol's Turk's head cactus (Echinocactus horizonthalonius var. nicholii) is one of multiple species of Echinocactus horizonthalonius. The Nichol’s Turk’s head cactus ranges from blue-green to yellow-green. It tends to be around 46 centimeters tall and has about a 20 centimeter diameter. It has 8 ribs that are lined with spines. The cactus blooms from April to May with a purple flower and white, hairy fruit.[127] Like many cacti, it is rather slow growing at a rate of just 2 inches in 10 years, due to minimal nutrient input.[128] Its habitat is located mainly in the Vekol and Waterman Mountains in Arizona and it has a population in the Sierra del Viejo Mountains of northwestern Sonora.[129] The cactus is particularly fond of Horquilla limestone outcrops.[130] The biggest threats to these cacti are habitat loss to new development, vehicle/off-roading damage, mining, and human collection. Among other threats, erosion from foot traffic from drug and human trafficking in the area.

Climate change

North American Deserts, as in most arid systems, experience water and temperature change as the most limiting factors in this ecoregion. Climate change's major impacts thus far have been an increase in average annual temperature as well as an increase in average annual rainfall.

The most prevalent factor is the increase in rainfall events and the severity of the events. Between 1931 and 2000, there have been measurable increases in seasonal rainfall during the summertime monsoon in the southern United States and northern Mexico. Because of this increase in rainfall, changes in the vegetative cover have caused native species to disappear and invasive species populations to rise. The kangaroo rat, which also supported Mojave rattlesnake and burying owl populations, has essentially disappeared from the Chihuahan Desert, while the non-native Bailey’s pocket mouse has colonized the area. Increased rainfall has also led to decrease in soil quality and less vegetative cover, which leads to increasingly higher temperatures. In the Sonoran Desert, anthropogenic land degradation as well as natural erosion from increased rainfall has caused a 4–5 degree increase in average afternoon temperatures, which means for many species less available water and nutrients they need to survive. These effects will lead to less biodiversity in the area, which is one of the main combatant factors that biota have against climate change.

As the effects of climate change continue to develop, North American Deserts will be increasingly affected, leading worsening biodiversity loss and decreases in the ecoregion productivity. Deserts are one of the most delicate ecosystems, relying on limited water and nutrient sources to survive. When these careful relationships are disturbed by the unpredictable and worsening effects of climate change, it will be very hard for these ecosystems to recover or endure.

Bailey's pocket mouse

Natural resources

In the North American Deserts there are emerging natural resources within the ecosystem. A few natural resources within the desert consist of oil, sunlight, copper, zinc, and water.[131] Some of these resources are renewable and some are non-renewable. Most of these resources are being exploited by humans and most actions are not sustainable. Sunlight is one of the deserts most important resource as it is renewable and has sustainable exploitations. Deserts within North America tend to have fields of solar panels, so they can reuse the sun as energy. Areas such as New Mexico, Texas, Arizona, and the Great Basin area, put up fields for green energy.[132] We monitored how the sun provides energy for resources such as plants and animals; we decided to make solar panels to produce energy for us.[131] Water is also a resource found in the desert that can be reused and has sustainable exploitations.

Oil is the most exploited resource within the deserts. In the North American desert most of the oil is found within the Great Basin region and this resource is non-renewable.[133] Oil is mined out of rocks and creates massive holes that disrupt the ecosystem.[134] The process with taking oil is not sustainable and this resource is scarce. Another resource that is mined is copper. Along with oil, this resource is also scarce as it is non-renewable and also has the same mining affects as oil does. This resource can be used for things such as computers, TVs, cell phones, and other electronics.[133] Copper is mainly found in California.[133] Other mined resources consist of zinc, uranium, rocks, jade, crystals, gold, and quartz.[132]

Notes

  1. 1 2 "Ecological Regions of North America: Toward a Common Perspective" (PDF). Commission for Environmental Cooperation. 1997. Retrieved 2008-04-10.
  2. ↑ "Ecoregion Maps and GIS Resources". United States Environmental Protection Agency. Retrieved 2008-04-10.
  3. ↑
  4. ↑ Bell, Trevor. "Arctic Cordillera Ecozone." Natural Environment. J.R. Smallwood Centre for Newfoundland Studies, Nov. 2002. Web.
  5. ↑ Government of Canada. (12/19/2012). Human Activity and the Environment. Statistics Canada. Retrieved March 10, 2013 from http://www.statcan.gc.ca/pub/16-201-x/2007000/10542-eng.htm
  6. ↑ Jeffers, Jennifer. "Climate Change and the Arctic: Adapting to Changes in Fisheries Stocks and Governance Regimes." Ecology Law Quarterly 37.3 (2010): 917-66. ELQ. Web.
  7. ↑ http://ecozones.ca/english/zone/ArcticCordillera/land.html
  8. ↑ http://www.ec.gc.ca/rhc-wsc/default.asp?lang=En&n=E94719C8-1
  9. ↑ http://canadianbiodiversity.mcgill.ca/english/ecozones/arcticcordillera/arcticcordillera.htm
  10. ↑
  11. ↑ Kerr, R. (2002). A warmer arctic means change for all. August 30, 2002. Retrieved from http://sfx.uvm.edu/UVM. March 11, 2013
  12. ↑ Durner, G.M. (2009, November 05). Polar bear sea-ice relationships. Alaska science center.
  13. ↑ Richardson, E. (2009). Polar Bear Life History and Population Dynamics. InfoNorth. Retrieved from http://pubs.aina.ucalgary.ca/arctic/Arctic62-4-491.pdf
  14. ↑
  15. ↑ "Conservation of Polar Bears in Canada". Government of Canada, Environment Canada. N.p., 20 Aug. 2012. Web. 25 Feb. 2013.
  16. ↑ Fellin, D. and J. Dewey (March 1992). Western Spruce Budworm Forest Insect & Disease Leaflet 53, U.S. Forest Service. Retrieved on: September 14, 2008.
  17. ↑ Kokelj, S.V.; Burn, C.R. (2003). "'Drunken forest' and near-surface ground ice in Mackenzie Delta, Northwest Territories, Canada". In Marcia Phillips, Sarah Springman, Lukas Arenson. Proceedings of the 8th Int'l Conf. on Permafrost. Rotterdam: A.A. Balkema. ISBN 9058095827. Retrieved 2 April 2013.
  18. ↑ "Bowhead Whale (Balaena Mysticetus) - Office of Protected Resources - NOAA Fisheries." Bowhead Whale (Balaena Mysticetus) - Office of Protected Resources - NOAA Fisheries. NOAA Fisheries Office of Protected Resources, 5 December 2012. Web. 24 Feb. 2013.
  19. 1 2 Finley, K. J. (2001). Natural History and Conservation of the Greenland Whale, or Bowhead, in the Northwest Atlantic. Arctic, 54(1), 55.
  20. ↑ Lambertsen, R. H., Rasmussen, K. J., Lancaster, W. C., & Hintz, R. J. (2005). Functional Morphology of the Mouth of the Bowhead Whale and its Implications for Conservation. Journal Of Mammalogy, 96(2), 342−352.
  21. ↑ http://animals.nationalgeographic.com/animals/
  22. ↑ http://www.sonic.net/~birdman/arctic/adaptations.htm
  23. ↑ Chernov, I. I. (1985). 8. The living tundra (pp. 174−176). Cambridge: Cambridge University Press.
  24. ↑ http://www.mbgnet.net/sets/tundra/animals/index.htm
  25. ↑ Tundra Animals. (n.d.). Tundra Animals. Retrieved March 11, 2013, from http://www.tundraanimals.net/
  26. ↑ "Tundra Threats" 2013
  27. ↑ Public Land Order 2214," 2008
  28. ↑ Purposes of the Arctic National Wildlife Refuge
  29. ↑ "Alaska Endangered Plants". Alaska Nature: Explore the Wonders of Alaska.
  30. ↑ "Endangered Animals in the Tundra". Animal Port.
  31. 1 2 Overpeck et al 1997
  32. 1 2 Budzik, 2009
  33. 1 2 USEIA 2012
  34. ↑ Dowie 2009
  35. ↑ Fletcher, B; Gornal, Poyatos, Press, Stoy, Huntley, Baxter, Pheonis (2012). "Photosynthesis and productivity in heterogeneous arctic tundra: consequences for ecosystems function of mixing vegetation types at stand edges". Journal of Ecology 100 (2): 441–451. doi:10.1111/j.1365-2745.2011.01913.x. Cite uses deprecated parameter |coauthors= (help)
  36. ↑ "Tundra Animals".
  37. ↑ "Dry, Cold and Windy".
  38. ↑ "Potential impacts of proposed oil and gas development on the Arctic Refuge's coastal plain: Historical overview and issues of concern".
  39. ↑ http://www.eoearth.org/article/Marine_West_Coast_Forests_ecoregion_(CEC
  40. ↑ http://www.nrs.fs.fed.us/pubs/gtr/gtr-nrs-80chapters/9-perakis.pdf
  41. ↑ Why the West stands tall
  42. ↑ Kauffman, Eric. "Climate and Topography" (PDF). California Department of Fish and Game. Retrieved 25 April 2013.
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