Why do plants and animals need to be fast growing in deserts
Xerophytes are plants that usually grow in extremely dry or arid conditions. Deserts occur in areas where rainfall is less than 50 cm a year. There are deserts like the Sahara of North America and the deserts of southwestern U.S Mexico and Australia that occur at low altitudes and then there are the cold deserts that occur in the basin and range area of Utah and Nevada and in parts of western Asia. Deserts are of four kinds i.e cold, hot and dry, semiarid and coastal.
Desert plants like Agave and Aloe, the leaves become thick leathery or abundantly succulent. In these the stem is reduced. Stomata in in many of these plants close in day time. The stem epidermal surface is covered with waxy material which prevents water loss by way of cuticular transpiration.
Deserts are home to many reptiles, insects, bird, and small mammals. Few large animals have adapted to desert life because their size makes it difficult to find shelter from the heat and they are not able to store water.
"Fast growing" is a manner of plants adaptations in order to survive in dry lands.
Some plants develop quickly from seeds buried in soil in the long dry period. Insects feed on plants,meanwhile pollinating flowers that will make thousands of seeds before the rain water to evaporate completely, thus ensuring a new generation.
North American Agava grows for 15 years before it blooms. When it rains, their flower produces seeds rapidly.From plants' seeds new plants are being developed, and the old plants die.
In general, plants lose more water through the leaves, but the desert plants have to hold water. Some have special leaves ,"water accumulating" .Other plants lose their leaves during periods without rain. Once rain water dries, it's leaves fall to save water.
All plants have to survive to dry periods and to animals that eat their leaves.
Most land plants take their needed water from the soil, by roots. They need water to cook their food by photosynthesis. In leaves, some water turns into vapours, which are lost in the air. Always soil water goes up in the plant and goes out in the air, in this way. If plants are left without water, first wilt, then dry, and if not receiving water, they die.