Low on Water

Copyright 1997 - The Multimedia Library (http://www.multimedialibrary.com.)

For the North American continent, the primary desert areas lie in the "rain shadow" east of the mountains of the central west coast. Moisture arrives at unpredictable intervals and usually goes away rapidly. Water can soak rapidly into the ground or evaporate quickly. Often, precipitation arrives in large amounts when it comes; the surface layers of soil become saturated and flash floods take away any excess water. Vegetation in these areas must deal with reduced availability of ground water and extreme heat. The low areas, such as those of Death Valley, contain large salty areas, leading to vegetation with high tolerance for salt.

A common feature of desert areas is the "playa" lake - which are shallow basins which only contain water intermittently. When they dry out, a cracked clay-mud surface is left behind.

Some desert plants are also ephemeral; they only blossom during brief rainy periods. Like plants of the forest undergrowth, they take advantage of conditions which only last for a short period.
Death Valley in bloom

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