Ecoregion: Desert Arid Page: 1
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In 1849, a group of pioneers seeking the fabled western gold
mines became lost in a dry and .
..,, ,-.,, a -e-J ro:.c-n: - Although only one of them died before
they were rescued, this desert area of exceptional heat has been known since as
"Death Valley."1 Death Valley is part of the dry mountainous Southwest ecoregion,
which includes the Mojave, Sonoran, Great Basin, and Chihuahuan deserts, as well
as the Colorado River and Rio Grande basins and the surrounding mountain ranges.
These arid lands of the United States lay nestled between the mountain ranges of
the Southwest, in part because the high mountain peaks tend to block moisture
from both the Pacific and the Gulf of Mexico.2
Many different habitats exist throughout this mountainous desert region, including
arid places nearly devoid of vegetation; cold lands with low-lying shrubs; dry
grasslands; savannas with short, thorny trees; and alpine woodlands.3 Mountain peaks
tend to experience more rainfall, leading to isolated alpine meadows and moist forest
habitats surrounded by low-lying deserts.4 The arid Southwest experiences extreme
temperature fluctuations, intense winds, seasonal precipitation, and wildfires.
Despite the lack of water, many areas of the arid Southwest ecoregion are home to
an extraordinary variety of species. Some plant species avoid the heat and lack of
water by remaining in seed form during the driest parts of the year. Then, when the
rainy season arrives, the plants quickly burst into full bloom before producing seeds
that remain dormant until the next rainfall.5 Other plants, such as cacti, survive the
whole year by storing great quantities of water during the rainy season, which they
gradually deplete during the dry season.6 Animals also exhibit unusual adaptations in
order to survive the high temperatures and lack of water. Snakes, bats, and rodents
hide in cool underground areas during the day and only come out at night in order
to escape the heat.7 Other animals dissipate the heat with adaptive mechanisms. For
example, jackrabbits have large ears that help radiate heat away from their bodies
while turkey and black vultures urinate on themselves to cool down.'
IMPACTS OF CLIMATE CHANGE
Climate models predict that the average temperatures in the Southwest could rise
by 7 to 12F (3.9 - 6.7 C) by 2090.9 The higher temperatures will create water
stress by increasing evaporation rates, and may also cause migrations of species
already living near their heat tolerance range. For example, tree species living on
mountain slopes are expected to migrate up in elevation, by approximately 350 feet
per degree Fahrenheit.10 Species such as the bristlecone pine will be trapped on
mountain tops and will not be able to migrate away from the rising temperatures."
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U.S. Global Change Research Program. Ecoregion: Desert Arid, text, June 2009; Washington D.C.. (digital.library.unt.edu/ark:/67531/metadc29333/m1/1/: accessed April 27, 2017), University of North Texas Libraries, Digital Library, digital.library.unt.edu; .