Wildlife of the Deserts [antikvár]

Preface For many people, the word "desert" conjures up an image of lifeless sand dunes stretching off to the horizon and shimmering in midday waves of heat. Dictionaries define deserts as barren, uninhabited regions; to be "deserted" is to be abandoned or forsaken. And yet to many, visiting a desert inspires the same wonder and has the same spiritual impact as contemplating the ocean or a mountain has on others. To these "xerophiles," the awesome vistas, cloudless skies, and dazzling sun afford the same sense of belonging to an ultimate reality greater than themselves as does the sight of the heavens on a starry night. Regardless of what the dictionaries say, deserts are far from uninhabited. No desert is without some forms of life. To be sure, the very driest regions—those with less than 50 millimeters of rainfall a year—are sparsely inhabited; but more than three-fourths of what are commonly called deserts have annual precipitation ranging from 50 to 250 millimeters and generally have very diverse plant and animal life. Because living conditions are severe, desert plants and animals must possess highly specialized characteristics of structure and behavior in order to survive. As a result, they are particularly interesting to professional ecologists and amateur naturaKsts alike. All the major deserts of the world are inhabited by people, and have been since well back in prehistory. Far from feeling abandoned or forsaken, these people look on the desert as their home. They understand the sources of sustenance it contains as well as its hazards. It becomes a part of their pastimes, their art, their religion. Indeed, many desert dwellers have considered the city a source of evil and looked down on sedentary city types. To this day, many individuals who have moved to the city because of its cultural advantages or the need to make a living, escape for periods of time to open country and live like nomads in tents. What we normally think of as deserts cover about 15 percent of the Earth's land area, and one person out of every 20 in the world is sustained by their biological )roductivity. This may seem like a comparatively small raction of the world's population, and "it may be thought that the food and fiber needs of such beneficiaries of the desert could be provided from other parts of the world. Hence, loss of the desert's productivity through improper use and inadequate conservation may not seem to be any great cause for concern. But it is cause for concern. The world's population is continuing to grow at about 2 percent a year, which means that in the next 30 to 40 years it will double. With half or more of the world's people now inadequately fed, clothed, and housed, we wdll need to extract twice as much food and fiber from the Earth's surface in the next half century just to keep our standard of living from declining. To lose any of the Earth's existing productivity would make an already staggering problem all the more difficult. Furthermore, the world's deserts are now misused and are producing at less than their potential. With proper management, they could yie d more than they do now to relieve the crowding and deprivation that prevails in many regions. A given area of the Earth may contain dozens of species of plants and vertebrate animals, several hundred species of invertebrate animals, and countless microscopic plants and