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Name: Colton
Status: student
Age: 12
Location: N/A
Country: N/A
Date: 10/9/2004


Question:
Why do more desert plants and animals live in hot deserts than in cold deserts?


Replies:
Hi Colton,

I'm not sure I agree entirely that more animals and plants live in hot deserts. The Sahara is pretty barren, but most deserts have some sort of sturdy living creatures that have adapted to this harsh environment. Many larger animals live in cold deserts because the water doesn't evaporate as rapidly. However, these animals are usually solitary. You won't find herds of animals in the desert, there's not enough food.

There are a series of videos you might like to rent or find at the library. They're called "Eye-Witness" videos. There is one on the desert that you would probably like very much. There is also one on weather if you are interested in what makes these climates, and the last one I'd recommend is called Rainforest. It's kind of the opposite of the desert, it's a good way to compare what a BIG difference what makes in these climates.

Have fun learning about the desert.

Martha Croll


I'm not really sure what specific places are meant by "cold deserts", but I know the general idea. Cold deserts might include Antarctica and the North polar icecap (places all covered with snow and ice), and barren rocky high altitude places like 20000-ft mountaintops and the high plains next to the Andes mountains in Chile. I wonder if tundra qualifies as a cold desert? Or the moon-scaped tops of volcanoes in Hawaii?

The high temperature and strong sunlight in hot deserts are only partial enemies of life. To live with those 2 is a little harder, requires some adaptation, but both heat and light were originally good things that living organisms need. The low humidity and rainfall is a worse problem. It's a 100% bad thing. None of our life can live without water. And there is usually some soil in hot deserts.

Cold deserts have the same lack of water, often worse, plus the temperature is often so cold that nothing can grow fast when it finally does get some water or food. Cold slows down chemical reactions, in plants, micro-organisms, and cold-blooded animals.

The most prominent life-forms in cold deserts are usually a small number of large warm- blooded animals. They range far for food (energy), and they carry inside them the humidity and heat that the desert won't provide. The absence of cold-blooded animals greatly reduces the variety of small, simple life-forms that could help an ecology develop. In some cold deserts there is a little less sunlight to feed plants, or at high altitudes there is more UV light to hurt them. At the poles there is night for months. Hibernation takes adaptation, too. No hot deserts have that problem. Many cold deserts have less useable soil than the average warm desert. Plants aren't real fast at climbing to the top of the snow that just fell on them. Cold deserts are almost purely rocky, or are covered with ice. Living things stay alive by "playing a smart game", and it's usually harder to find a smart game to play, in an environment that has only two or three things in it. Simple environments are often tough to colonize.

I guess there isn't really one answer, Colton. There are many slightly different kinds of deserts, and many possible sets of reasons why life can't multiply to high density.

Jim Swenson



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