4 Protected areas and biosphere reserves in the cold deserts and subdeserts.
1.1 General considerations
There are undeniably biological, geographical, and cultural differences between the cold and hot deserts, but, as a whole, the problems of conservation of biodiversity and strategies for nondestructive development are similar. In both, sustainable development is impossible without ensuring continuity and use of genetic resources, let alone maintaining the current form of development.
Some of the staple crops on which much of humanity depends (wheat, barley, sorghum, millet, as well as many fruits and vegetables, numerous medicines, and some domesticated animals such as the ass and camel) originated in arid or semiarid areas. Furthermore, the means of subsistence of almost a billion people depends on the sustainable exploitation of these resources.
Threats to the environmental conservation objectives
The phenomena associated with desertification are especially evident in the grazing areas of the protected cold deserts, where an estimated 22% of the soil is seriously degraded, and its food production capacity and biological productivity have fallen sharply. Desertification is often the result of unsustainable farming and grazing practices. Frequently, it is not taken seriously because it only affects specific sites, not an entire nation. The measures that can be taken to resolve desertification problems on the local level often go unheeded because they are not fully understood by the local population.
The best--if not the only--way to preserve biodiversity is by designating protected areas, protecting migration routes, and maintaining traditional desert cultures. And this has to be done on the basis of what needs protection and what can still be protected, which is often not a lot. A zoning system should be established that incorporates and favors the development of the resident human population, as stated in the charter of the biosphere reserves.
Unlike mountain, forest, and coastal ecosystems, where natural barriers clearly mark the divisions between the park and pre-park, in desert areas the regions of greatest biological importance are often highly dispersed, and it is important to designate zones that will be managed in different ways. The scientific research areas and the strictly protected zones, which require greater protection, are governed by regulations that are hard to enforce, and these areas often need to be fenced off--an expensive undertaking.
Research in protected areas
Current research pays special attention to the stable desert zones. In these zones, it is possible to determine the long-term effect of isolated events (such as climatic change) and regularly occurring events (such as desertification), just as it is possible to monitor the changes most directly and immediately caused by human intervention (such as stockraising). Studying these areas is important because it represents a major contribution to gaining useful and essential experience on active and focused management. All the reserves--from the Desert Experimental Range in Utah (United States) to the Repetek Biosphere Reserve (Turkmenistan)--already carry out broadly based research programs.
The desert ecosystem is extraordinarily complex and includes many environmental interactions and many widespread anthropogenic disturbances. It seems, for example, that diverting watercourses may have serious consequences, but further study is needed. Little is known about how animals and plants might react to higher salt content in the water and air, or how this might affect human beings, especially when considering the incidence of respiratory and eye diseases. The stockraising industry should also evaluate the long-term consequences of increased levels of salts on meat and milk production.
A very interesting study carried out in the Turan protected area (Iran) has shown that the classical ideas regarding the relation between grazing, agriculture, and desertification were often mistaken. The vulnerability of protected desert areas to these activities depends on several factors, among them the economic status of the people who exploit the area, the extent to which the carrying capacity is respected, the ability to alternate the use of different resources and thus allow sites to regenerate, and, perhaps most importantly, the application of environment-friendly technology. In the early 1980s, the decision to nationalize the Turan grazing areas was revoked, and an alternative program based on rent and grazing permits was applied.
In return for access to markets for their meat and wool products, the herders have taken responsibility for managing the grazing areas. New and more efficient technologies--such as replacement of caravans of camels by motor transport--have allowed partial recovery of the desert vegetation. The ready availability of fuel has made burning sheep dung unnecessary. Even more importantly, private ownership of land has restricted the activities of seasonal migrating herders. This has led to elimination of human activities in the most vulnerable regions, where wildlife populations have increased and native plant communities have spread.
There are many areas of research that are of potential importance in active management. These include irrigation, dune stabilization, forestry, the introduction and propagation of new plant species, and, especially, different means of transporting water efficiently. Some of these studies would make economic activities other than stockraising possible for the people of the desert. One of the most successful alternative uses of desert ecosystems is the collection of fruit and fuelwood, practiced on a small scale in the Patagonian Deserts.
Other alternative uses include cultivation of industrial crops such as guayule rubber (Parthenium argentatum, Asteraceae) in the deserts of Mexico and jojoba (Simmondsia chinensis, Simmondsi-aceae) in the deserts of the United States. These products are grown mainly for export but are also used in the local economy. For example, guayule rubber is used to seal leaks in irrigation channels.
There are now several international science and technology exchange programs, but research is unequally distributed, with much more research being performed in developed countries. Many recent scientific and technical discoveries, including use of computer programs for modeling local physical and social variables, cannot be applied in developing areas. Even so, research carried out in these areas may be very useful if it leads to the development of projects based on local materials and skills. Good examples of this are the design of irrigation canals and of underground water storage facilities that reduce losses by evaporation and help eliminate diseases spread by areas of open water.
In the deserts, especially the cold ones, current research focuses on stockraising. This has been the subject of work in the Desert Experimental Range and in the protected desert areas of Patagonia, and in the biosphere reserves in Iran, though the Turan Protected Area has also been chosen for several ethnological studies and a long-term research project into soil use.
It may seem that other interesting projects are being left out, but research projects are often dependent on external factors such as institutional financing and suitable infrastructure. Furthermore, many research projects focus on a very precise geographical area, meaning that large areas of the desert are left unstudied and unexploited, and it is not possible to determine the effects of long-distance industrial pollution or of disturbances caused by military uses.
1.2 The protected parks and areas
The subtropical cold deserts cover 2.26 million [mi.sup.2] (5.85 million [km.sup.2]), 9% of all dry land. They are present in central and middle Asia (1.9 million [mi.sup.2] [4.92 million [km.sup.2]]), in the western United States (301,158 [mi.sup.2] [780,000 [km.sup.2]]), and in Patagonia (57,915 [mi.sup.2] [150,000 [km.sup.2]]). Although they cover an area much greater than most other biomes, only 1% of the cold desert area is protected.
Protected areas in middle and central Asia
In the cold deserts of central and middle Asia, the protected areas are relatively large, which mean that their human populations are relatively small. The largest protected areas are the Gobi Biosphere Reserve (5,300,000 ha [1 ha=2.5 acres]) and the natural reserves in Kazakhstan and Turkmenistan-Krasnovodsk (262,037 ha), Kaplankir (570,000 ha), and Ustyurt (223,300 ha). About 10% of the desert area of Turkmenistan and Kazakhstan enjoys adequate protection, though the protected areas in these republics are heavily used. In the other states of middle Asia (Uzbekistan, Kyrgyzstan, and Tajikstan) and also in the subdesert regions of northern Afghanistan, there are no natural parks, and less than 1% of the area enjoys any form of protection. Examining the protection regime of these areas will show how effective they have been. In Asia, especially Iran, 30% of the protected area network is secured as nature reserves and national parks. Management was initially weak and ineffective due to political instability. In several of these areas, there has been intense and indiscriminate hunting, and forests have been cleared for agriculture.
The Biosphere Reserve of the Repetek Nature Reserve, administered by the Academy of Sciences of Turkmenistan, is by far the best studied of the cold desert biosphere reserves in Asia. In the former Soviet Union and its constituent republics, unlike in the western countries, reserves are chosen on the basis of their suitability for scientific research, not for their aesthetic or biological value. In Repetek, this scientific potential focused on projects related to water: 1) underground storage of water, 2) using salt water from within dunes to allow the vegetation to develop, 3) stabilizing dunes, and 4) digging drainage channels in the clay takyrs to form pools from which livestock can drink.
The management has also 1) carried out studies to assess the viability of replanting and stabilizing the barchan dune fields, 2) conducted research into the physiology of native plants and animals to see how they react to changes in salinity, temperature, and aridity, 3) studied the changes in the soil moisture regime, and 4) measured the effects of grazing on plant productivity.
In the Gobi Biosphere Reserve (Mongolia), an active research program is under way with international support, but much remains to be done. Several interdisciplinary studies have already been performed. A project is in progress between Mongolia, Russia (USSR until 1991), and the UNEP to draw up a complete study of the area's geological and ecological characteristics. There are also efforts in the fields of rural technology, energy flows, ecosystem organization, and other restoration projects within the strictly protected zones.
The Gobi Biosphere Reserve has the best facilities of the seven biosphere reserves in the cold deserts. There are three weather and water stations (in Toorai, Ekhiin Gol, and Baitag). The maintenance staff also has a light survey aircraft, conference rooms, accommodations for visiting scientists, and research centers for university students.
Protected cold deserts in North and South America
In the cold desert regions of the United States, there are several very large protected areas, including the Desert Nature Reserve (1,590,044 acres [643,471 ha]) and the Glen Canyon Protected Landscape (1,434,584 acres [580,558 ha]), both of them in Nevada. There are also several smaller national parks such as Bryce Canyon (35,595 acres [14,405 ha]), Canyonlands (337,401 acres [136,542 ha]), Zion (146,553 acres [59,308 ha]), and Arches (72,303 acres [29,260 ha]), which are all famous for their geological formations. The Patagonian Desert contains far fewer areas, and the only large area is the Valdes Peninsula Multiple Use Reserve, which covers 889,576 acres (360,000 ha).
The Great Basin Desert is the largest of the cold deserts in North America. The monotonous and seemingly endless landscape is also the least spectacular. Yet the mountain chains that separate the sun-bathed, shrub-covered basins house an unusual boreal biome that differs from one basin to another, and they constitute a natural barrier to the spread of plants and animals. Few desert areas contain such relatively large, untouched areas with archeological remains of the first human settlers of North America. Until recently, it was thought that these large wilderness areas did not require special protection because so few people lived in them; it was one of the few important biomes present in the United States that was not represented in the National Parks Service. In 1984, studies into the effects of stockraising and mining on the desert environment led to the designation of more than 20 natural areas, and in 1986 the Great Basin National Park (76,800 acres [31,080 ha]) was created. Its declaration as a national park was criticized because, unlike other national parks, it does not seek to protect a site of great natural beauty and recreational value. It even allows stockraising and mining. Stock animals, apart from horses, were introduced into the area by the Mormon pioneers and the California gold prospectors of 1849. Stockraising is considered an integral part of the Great Basin is therefore also protected.
In Argentina, the current system of protected areas favors the steppes of the Andes over the grassy pampas of Patagonia, where human impact is, in fact, much greater. The only UNESCO Biosphere Reserve in the cold deserts in Argentina is Laguna Blanca, at an elevation of more than 9,843 ft (3,000 m). The limited regional development has often held back the integration of national parks and provincial reserves in the planning process, and colonists and gold prospectors have made it difficult to obtain the cooperation of the local people in the development of the protected area. Attempts are now being made to manage the protected areas in a way that allows multiple uses. As in the biosphere reserves, the local population is allowed to continue producing food, but areas have also been designated for ecological research and monitoring. In the deserts of Patagonia, there are two protected areas of this type--Trevelin (7,487 acres [3,030 ha]) and the Valdes Peninsula (889,576 acres [360,000 ha])--and there is also the Bosques Petrificados (petrified forests) National Monument. Several parks and reserves located high up in the Andes show physical similarities with the Patagonian Desert, among them areas of the Nahuel Huapi National Park (1,057,854 acres [428,100 ha]), which was the first protected area in South America.
In the most protected areas, the guanacos, Patagonian cavies (guinea pigs), and tinamous (game birds) are more and more common, thanks to the training of the staff and the incorporation of natural science students, who help the ranchers and serve as tourist guides. In both Trevelin and the Valdes Peninsula, long-term studies have been performed on wild populations, and the behavior of the most important species has been monitored. The Patagonia Nature Center is also performing research into the viability of reintroducing native plant species into areas grazed by livestock--research that is supported by the landowners. The more information available, the less hunting occurs, even though hunting is restricted to the owners of fincas.
However, in the valley of the Rio Negro in the northern part of the desert, large hydroelectric schemes are being constructed. It is still not known what ecological impact these and other projects will have; in the Nahuel Huapi National Park, though, boats and activities from the nearby city of Bariloche have greatly polluted the lake and surrounding desert. Erosion is often the result of grazing by livestock, but other forms of exploitation (mining and energy exploitation) play a role. Coal, gas, and oil have been found in the Comodoro Rivadivia region. On the mountain slopes of the west of the desert, iron, zinc, lead, and uranium deposits have been found. All these industries take precedence in the area, and this eventually damages the soil.
2. The UNESCO biosphere reserves in the cold deserts and subdeserts
2.1 The biosphere reserves in the cold deserts and subdeserts
There are only seven biosphere reserves in the cold deserts. All but two--the Desert Experimental Range (United States) and the Laguna Blanca National Park (Argentina)--are in Asia. The Asian cold desert biosphere reserves occupy a total of about 19.8 million acres (8 million ha), 12.4 million acres (5 million ha) of them in the Mongolian Gobi. There are two reserves in Iran (Kavir National Park and the Turan Protected Area), one in Mongolia (the Gobi), one in Turkmenistan (the Repetek Nature Reserve), and one in China (Mount Bogda). They may appear less important in quantitative terms than those of other biomes, but some of these biosphere reserves are among the most active and innovative around.
In areas as remote and unpopulated as the unexplored regions of the Gobi Desert, simply designating an area "protected" is some assurance of correct management, even though supervision is minimal. The situation is very different in the smaller and more densely populated areas. In these cases, the effectiveness of management depends on other factors such as the facilities, the infrastructure, the budget, the legal framework, and, above all, the cooperation of the local people. For example, the Iranian Environment Department is seeking to gradually reduce the human population so that nature can recover from so many years of abuse. Small craft activities are still allowed there (charcoal production), but hunting, farming, and clearing vegetation are restricted to those with permits. Because a mere 11 people are responsible for supervising the million-hectare site, the cooperation of local people is essential.
2.2 The biosphere reserves in the cold deserts and subdeserts in the Americas
There is only a single biosphere reserve in the cold deserts of South America, the Laguna Blanca Natural Wildlife Biosphere Reserve (2,425,626 acres [981,620 ha]), which is on a plateau at an elevation of more than 9,843 ft (3,000 m). The core of the reserve occupies 403,892 acres (163,450 ha) in the Pasto Ventura locality and was selected for its difficult access and because it is the most important habitat of the vicuna (a wild ruminant related to the llama). The rest of the reserve is a peripheral area where, among other less important activities, sheep, goats, horses, and cattle are raised. The region is rationally managed with the help of the reserve's research staff. One of the exceptional characteristics of this reserve, which does not occur in other protected desert areas in Argentina, is the close collaboration between the local people and the research staff. The High Altitude Experimental Research Station, which is carrying out most of the research projects, was built on ground ceded by local landowners and includes houses for the scientists. In exchange, the scientists continue to undertake research into more efficient livestock management methods. These include 1) selecting the llamas to improve the quality of their wool, 2) studying the optimal carrying capacity for stimulating productivity, and 3) establishing a zoning system of the plant communities to ensure their regeneration.
The southern desert regions of California, Arizona, and New Mexico, which extend into Utah and Nevada and reach Wyoming and eastern Oregon, share a series of characteristics that define them as cold deserts. For example, their climate is highly seasonal, the daily temperature range is large, and water is scarce. These arid zones can be divided into different deserts on the basis of their geology, biology, and degree of human disturbance. The UNESCO Biosphere Reserves Program is not hindered by the often contradictory aims of both use and conservation. At the only biosphere reserve in this region (the Desert Experimental Range; 55,630 acres [22,513 ha]), efforts are made to combine both. This is done by means of a system of zones where grazing by cattle is strictly controlled and is complemented by ecological studies. It is too early to say if the reserve will be able to combine them successfully, but studies performed have shown that it was worth declaring it a protected area, as the excessive degradation the area previously suffered has been reduced since appropriate management was introduced.
The Desert Experimental Range Biosphere Reserve
The Desert Experimental Range Biosphere Reserve is in a basin surrounded by the Wah Wah Mountains, roughly halfway between the cities of Milton and Garrison (Utah, United States). Most of the arid region of the Great Basin is considered unfertile. There are few private properties, as the lack of water makes agriculture difficult. The region is only of interest to nature lovers, a few cattle ranchers, and the large federal agencies.
The Desert Experimental Range Biosphere Reserve was designated when the Federal Land Management and Policy Act was passed in 1976. This law recognized public interest in preserving the grazing areas in the zone for the future enjoyment of the people of the United States. It also offered citizens the opportunity to express their opinions on the activities of the federal agencies, on the activities of mining companies, and, most importantly, on the renting of pastures. All of these had negatively affected the reserve's aesthetic value and wildlife.
Research began in the 1930s and until recently focused on maximizing pasture productivity. The latest work on the dynamics of this desert ecosystem has shown that, despite the availability of suitable technology to increase productivity, the rate of recovery is low, erosion is increasing, and the number of animals the area can support is consequently decreasing. The American public is increasingly aware of environmental issues and insists on the conservation of all the areas where indigenous peoples live.
Characteristics and natural values
The Great Basin Desert consists of about 150 smaller basins divided by about 160 mountain ranges running north-south. In the deepest of these basins, it is still possible to recognize the playas of the lakes present during the Pleistocene, when the climate was colder and wetter. As the climate became warmer and drier, the lakes evaporated and left salt flats. Many of these basins fill from time to time, but they have no outlet to the sea. Evaporation is usually greater than the water input, especially in the hot months of summer, so these lakes dry out rapidly and leave salt flats covered with halophilous shrubs and bare soils.
In the past, the relief of the Great Basin was dominated by playas formed by the large alluvial fans running gently down from the surrounding mountains, giving the impression that the mountains were buried in their own rubble. In the playas and the lowest parts of the alluvial fans, where most of the salts are deposited, the sandy loams, as well as silts and clays, are highly saline and alkaline. They are derived from deep lacustrine deposits, but their formation depends on the soil's salt content, the soil class, and the depth of the water table. In the areas where there is substantial plant cover, the organic matter and nutrients accumulate around the shrubs and form a microrelief with rises where a few perennial vascular plants manage to live. The surface is often covered with a saline crust colonized by lichens, mosses, and fungi.
The Great Basin has a continental climate with very marked daily and seasonal changes in temperature and rainfall, caused by geographical features and atmospheric circulation patterns associated with the winds that come from the west. The elevation and the continental nature of the climate are perhaps the most important geographical variables. The mountain ranges to the west are an obstacle preventing moisture-bearing winds arriving from the Pacific; they cast a rain shadow on the Great Basin Depression, resulting in the bottom of the depressions receiving only 8 in (200 mm) of rainfall a year. In winter, the cold air flows to the bottom of the depressions, where temperatures are lowest. In summer, the continuous solar radiation means that temperatures are very high.
Unlike the other plant communities of the Great Basin, the halophilous shrubs of the Desert Experimental Range grow in highly saline soils. Their bright green is in stark contrast to the areas to the north and the south, which are mainly gray. The intense green color is due to the fact that the plants receive enough water from the water table, which is only 12 in (30 cm) deep in some places. This halophilous scrub covers 50,387 acres (20,391 ha) in the reserve, 95% of its area, and consists of four different communities. The shadescale (Atriplex confertifolia) communities are by far the most widespread, largely due to the plant's rapid growth. The different species of Atriplex are not only associated with each other but also with other relatively halophilous species such as the sagebrush (Artemisia tridentata) at higher altitudes and the big greasewood (Sarcobatus vermiculatus) in areas where only the topsoil is highly saline. Many other shrubs grow mixed in with the shadescale--the chenopods Atriplex spinescens and Sarcobatus baileyi, Chrysothamnus viscidiflorus (Asteraceae), and Ephedra nevadensis (Ephedraceae). These plants are generally spiny and their ground cover is less than 10%.
Shadescale is dominant everywhere, except where the water table and soil salinity are very high. In such circumstances, there are two different communities, those of greasewood and those of shadescale. Greasewood is a good indicator of the presence of underground water, as its deep roots can take up the water below the alkaline soil where shadescale roots. This community occurs throughout the reserve but is more common at higher altitudes, where the greasewood roots can grow to a depth of 13-16 ft (4-5 m). Winterfat (Krascheninnikovia [=Eurotia = Ceratoides] lanata) also tolerates saline soils, but it normally grows in very wet areas in saline-alkaline soils where shadescale does not form a continuous cover. Winterfat is excellent fodder for cattle and sheep and is sometimes cultivated in zones where shadescale has been eliminated.
The worst represented community is the rabbitbrush (Chrysothamnus graveolens, Asteraceae). This grows in sites at higher elevations, together with the grasses Bromus tectorum, alkali grass (Distichlis spicata), dropseed (Sporobolus airoides), and different species of prickly pear (Opuntia). Once it has germinated successfully, rabbitbrush spreads, and it may well eventually become dominant due to its vegetative vigor, its high production of seeds, and its long roots.
The low animal diversity and productivity in the Desert Experimental Range are largely the consequence of the dominance by single-species plant communities. Animals, especially large animals, have varied nutritional requirements, and very few are able to survive on a diet of a single plant species. The only native ungulate present is the pronghorn (Antilocapra americana). Its populations have declined as a result of overgrazing by cattle, which has reduced the quantity and quality of its grazing area. The survival of the young is directly related to the distribution of the summer rains, which support the growth of the fodder they need. Some other ungulates--such as the mule deer (Odocoileus hemionus), bighorn (Ovis canadensis), and wapiti (Cervus elaphus canadensis)--are occasional visitors to the range when their sagebrush pastures to the north are covered with snow.
The native mammal fauna is dominated by rodents and lagomorphs (rabbits and related species). There are eight species of reptile, among them the little prairie rattler (Crotalus viridis). Forty species of bird have been recorded, though very few apart from the birds of prey are resident. The black-tailed jackrabbit (Lepus californicus) is the most frequent mammal, with a population density of 60-600 individuals/km2. Trapping experiments have shown that even the smallest populations of jackrabbit have a greater biomass than all the other rodents put together.
The jackrabbits' impact on the vegetation is seven times greater than that of the sheep, because they pull the leaves off and leave them on the soil without eating them. Due to increase in the number of annual species, many rodents have been able to take advantage of this habit. The chisel-toothed kangaroo rat (Dipodomys microps), Ord's kangaroo rat (D. ordii), the deer mouse (Peromyscus maniculatus), the western harvest mouse (Reithrodontomys megalotis), the kangaroo mouse Microdipodops megacephalus, and the pocket mouse Perognathus longimembris form large populations in the greasewood and shadescale communities.
On the whole, the predatory mammals and the birds of prey that live in the reserve are the same as in the rest of the Great Basin, but they are less abundant. The coyotes (Canis latrans) are active predators of the jackrabbits. The populations of coyotes are limited by those of the hares: in the classic predator-prey relationship, the coyote population increases following any increase in the hare population. Other secondary consumers are the bobcat (Felis rufus), the American badger (Taxidea taxus), the long-tailed weasel (Mustela frenata), and the kit fox (Vulpes macrotis). The most frequent birds of prey are the prairie falcon (Falco mexicanus), the ferruginous hawk (Buteo regalis), and the golden eagle (Aquila chrysaetos).
The cultural heritage
Although an archeological survey has not yet been conducted, the finds in nearby areas such as the Paragonah-Parowan show that the area was inhabited by prehistoric populations and by the Pueblo cultures. This has long been supposed but has now been confirmed by 14C dating. The prehistoric post-Pleistocene cultures are dated 11,0002,400 years ago, though few sites show signs of continuous occupation.
It seems that the region's inhabitants followed a pattern of seasonal migration, abandoning the area when the climate was unfavorable; this has been confirmed by the analysis of plant and animal remains. The ecological and climatic changes are in agreement with the dating of the tools. A wide range of spear tips, millstones, and bone tools from several different sites all suggest that their camps were not permanent but simple staging points on their seasonal migrations.
About 2,400 years ago, a new culture arose, the Fremont or Sevier culture. It spread through the south of the Great Basin from the Wasatch Range in Utah to the Snake Valley (on the border between Utah and Nevada). The Sevier culture was based on cultivating maize (of unknown origin) and beans and squashes originally from Mexico. The people of the Sevier culture lived in small villages sited on alluvial fans. Their subsistence lifestyle was based on grazing and was complemented by horticulture. The most interesting remains of this culture are the houses, which consisted of a hole dug in the ground with rectangular roofing.
Some had flat rectangular storage surfaces, where baskets, clay figures, flat millstones, bone tools, and ornaments have been found. The Sevier culture became extinct at more or less the same time as the other Pueblo cultures of the Great Basin, and some scientists suggest it may have been due to a climate change. After careful analysis of each separate valley, Sevier tools have been found that date from 3,150 years ago, mixed with archeological remains similar to more modern Paiute craft products, suggesting that the Sevier peoples either decided to emigrate suddenly or they intermixed with the Paiute.
The life of the Paiute was very simple and well adapted to the natural conditions of this region of the Great Basin. Their subsistence activities followed an annual cycle and were performed communally. In the spring and summer, they gathered seeds, roots, and plants. If fish occurred, they caught them with nets and harpoons, and they used a wide range of traps and lures to catch wild birds. They hunted mammals such as rodents, deer, antelopes, and bighorn all year-round. In autumn, they collected nuts, their main foodstuff during the harsh winter.
The southern Paiute were not strictly nomadic, but their lifestyle was highly adaptable and their utensils were easily transported. They spent the summer in simple huts made of branches called wickiups, but in winter they built more stable dwellings with trunks and branches. Their few belongings were baskets, nets, millstones, bows, arrows, fishing tackle, skins, and containers.
The southern Paiute did not start to use horses until the mid-nineteenth century. By this time, other tribes had already adopted the Plains Indian culture based on hunting buffalo, as well as the warrior activities that brought them into conflict with the Europeans. The simple lifestyle of the Paiute survived intact until the first railways to reach the region encouraged the export of livestock products; this negatively affected the Paiute's traditional food sources.
Management and problems
As the Desert Experimental Range is very unproductive and is far from the large urban centers, a nature conservation management plan is almost unnecessary. Nor is it possible to increase stockraising, as the natural primary production is very low. The only direct menace is thus the extraction of minerals, which is widespread in Utah. Minerals such as salts used to be extracted only from unvegetated salt flats, but the mountains surrounding the 200 basins in this ecosystem contain very rich deposits of magnesium, zeolites, and sodium sulfate; petrol and natural gas have been discovered in some areas.
Despite the apparent stability of these regions, studies of the soil types, the changes in the vegetation, the climate, and the distribution of animal species have brought to light several urgent problems. The most serious and the most widespread is soil erosion. Precipitation is scarce in the basin, and the most important erosive agent is the wind--in both the alluvial fans and the lower valleys that contain most pasture areas. The spaces between shrubs are very exposed, and crystallization of salt particles near the surface makes it harder for water to percolate into the soil, thus favoring erosion. In summer, when the earth dries out, the soil disintegrates and the particles are blown away. Trampling by livestock has a similar effect, and a system of enclosures has had to be built to control the length of time each area is used.
In the fenced grazing at higher elevations, the erosion caused by livestock is very clear. At high elevations, water is the most important erosive agent. Erosion is favored by the arrangement of the vegetation in bands. The problem has been solved in some areas by digging ditches and making channels and holes to try and ensure greater infiltration of the water into the soil. Furthermore, when the perennial grasses are grazed continuously, annual grasses become dominant, and this greatly reduces the grazing available. The only thing that can be done is to resow the degraded areas with perennials or transfer the livestock during the growing season.
Until 1934, most of the Desert Experimental Range was open grazing, meaning it was open to all and not controlled by the government, although not many activities were carried out there. When minerals were found in other areas of the Great Basin, the shepherds (who were considered landless wanderers and thus without rights) had to take their herds much farther away. The Desert Range was considered a marginal area, and the shepherds had to build their own fountains, wells, and conduits to transport water to the highest slopes. To begin with, the shepherds did not follow any seasonal pattern, and the high demand for meat during the interwar years (between World War I and World War II) led to serious degradation of this area and other public land. A study performed during the Great Depression of the 1930s showed that 70% of the grazing land was degraded. This led to the passing of the Taylor Grazing Act of 1934, which made it compulsory to have a license for each flock and denied access to transhumant herds. The lack of legal and personal protection, together with excessive confidence in the Taylor Act, slowed down the reduction in stock levels, until in 1976 the area was declared a biosphere reserve and the Federal Land Management and Policy Act was passed.
The area's physical characteristics mean that it has never been very suitable for grazing. Attempts to increase stockraising and protect the wild animals (such as the pronghorn) have not been successful--even with active management--due to former abuse. The saline areas of the lower parts have very few palatable fodder species, except for a few areas with scattered patches of Krascheninnikovia lanata, and they are also without water. In the high slopes where the grasses Distichlis, Elymus cinereus, and Puccinellia are replaced by nonhalophilous plants, the nutritional value of the pastures is much greater. These plants produce very few woody tissues, and the livestock thus consumes almost all the aboveground parts. Studies into grazing management in the Desert Range have been conducted since 1934. The current experimental system did not begin until the 1950s, when many animals died as a result of the spread of non-native plants such as Bromus tectorum and the pepperwort (Lepidium perfoliatum). The most important of these introduced plants is Halogeton glomeratus (Chenopodiaceae), an annual central Asian species that contains very high levels of oxalates. When eaten by livestock, the oxalates precipitate calcium, thus preventing blood from clotting; this may cause the animals' death.
The invasion of exotic plants has given rise to numerous studies into the ecology of plants of desert sites, the physiology of the different types of plants, and the nutrient requirements of the livestock. Today, the Desert Range has stockades that separate a 1,829 acres (740 ha) control area from the experimental range (124 acres [50 ha]), which is divided into 43 precincts. A 1976 Act gave the shepherds different types of leases, but the effects of grazing have been carefully monitored. Some shepherds have adopted more effective grazing rotation schemes, but they still depend on funding to build fencing and water piping systems. Another problem with this method is ensuring that the pastures are rested in the years of abundant seed production. Additional trials include artificially sowing fodder species such as winterfat (Krascheninnikovia lanata) and rabbitbrush (Chrysothamnus graveolens) in the less saline areas. In the smaller grazing areas, fertilizers have been applied to native perennial grasses, including Sporobolus airoides and Distichlis spicata. This practice is very effective in wet years, but it makes the perennial species very susceptible to dry conditions and stimulates the growth of annual weeds such as Halogeton.
On the basis of the research carried out so far, scientific solutions do not appear as effective as the more rational projects that allow moderate use of the biosphere reserve as grazing for sheep. Sheep do not need a lot of water, and they can make use of the snow in high areas during the winter. They are very efficient grazers but do not represent a threat to the wild animals in the reserve because they almost never graze in the same area two years in a row. As they are very adaptable, they can be moved to other grazing areas quite easily. It is still unclear whether practices based on the current studies have managed to reestablish the ecosystem, but recent computer models that measure the intensity of defoliation tend to favor rational approaches.
2.3 The biosphere reserves in the cold deserts and subdeserts of Asia
Almost all the biosphere reserves in cold deserts and subdeserts are in Asia. They vary greatly in size. The largest is the Gobi Biosphere Reserve in Mon-golia, which covers five million ha (1 ha=2.5 acres) and is almost totally uninhabited and largely unexploited. This opens up innovative perspectives on how to equip it for sustainable tourist use and research. In Iran, the Turan protected area is also more than a million hectares in size. The smallest of the reserves in the cold deserts of Asia is the Repetek Biosphere Reserve in Turkmenistan, which is well equipped for research and has many years of experience in its favor.
The Repetek Biosphere Reserve
The Repetek Biosphere Reserve (38[degrees]14'N -68[degrees]11'E) and its station in the Sand Desert are in the Lebab province or welayat, in the center of the eastern part of the Karakum Desert in Turkmenistan. This desert stretches west to the banks of the Amu Dar'ya (see p. 307); it is part of the large Turanian Plains occupied by loess of wind origin, alluvial sediments, and large dune formations, normally running north-south and reaching a height of up to 39 ft (12 m).
Part of the area of the current biosphere reserve was first protected in 1928 as a zapovednik. This was a debatable form of nature protection introduced shortly after the Russian Revolution of 1917. The theoreticians of nature conservation in Russia in the early twentieth century considered the zapovednik should be a sort of reference sample of the natural communities of a given region--that it should be left untouched and only visited for scientific purposes. The zapovednik was thus similar to the strict reserves created by European and U.S. conservationists. In fact, the term is derived from zapoved, which means mandate or prohibition in Russian, and would correspond more precisely to a game reserve. In practice, the interpretation of zapoved has always been more lax than this; it corresponds better to the idea of a less restrictive nature reserve.
All the zapovedniki created by the central Soviet government, the federated republics, or the autonomous regions were state-owned, but the Repetek Nature Reserve was from its creation attached to the Turkmenistan section of the then-Soviet Academy of Sciences. In 1952 a decree of the Council of Ministers of the Turkmenistan Autonomous Republic extended it to its current limits. The reserve is divided into two areas: a strictly protected core covering about 37,066 acres (15,000 ha) and an experimental peripheral area of 48,432 acres (19,600 ha). Both in the reserve and the surrounding protected area, all activities that might alter natural phenomena are banned.
Characteristics and natural values
The main ecosystems of the eastern Karakum are all represented in the Repetek. The reserve's landscape is dominated by large massifs of fixed sands, vast areas of mobile barchan dunes without vegetation, and small depressions with scattered dense patches of plants. In the recent past, the reserve's population has been very low; even so the desert's natural ecosystems have been greatly altered by human activities. The main human disturbances at the moment are those that have to do with grazing by goats, camels, and karakul sheep. The effects of this grazing are more clearly visible in the area of sterile mobile dunes than in any other area of the Karakum.
Deserts are normally very short of water, but this is not the case of the Karakum. Beneath the rock layer is an underground lake that runs from the Amu Dar'ya in the east and the Caspian Sea to the west. The depth of this underground water varies, but it is generally more near the surface in the eastern area than in the western one. Within the reserve, the underground water is 13-16 ft (4-5 m) below the lowest dunes and somewhat deeper under the higher dunes. The underground water of the Karakum has three different origins, the most important of them being the Amu Dar'ya, which is only 31 mi (50 km) from the reserve.
This river has its headwaters in the foothills of the southern Pamir Mountains, which are covered by perpetual snow and glaciers at an elevation above 16,404 ft (5,000 m). In its lower stretches in the desert, the Amu Dar'ya has no tributaries and loses water to the underground lake. These underground waters are also fed by the rivers Murghab and Tedzhen, but they carry so little water in summer that they need not be taken into account. The third source of water is precipitations (rain and snow).
The Karakum has a highly seasonal continental climate. The measurements taken at the research station show that the average annual precipitation is 4.5 in (114.5 mm), almost 85% of which falls in the cold season, between December and April, when the winds blow northwest from the Pamir-Alai Mountains.
Most of the rainwater is lost by evaporation or by the transpiration of the plants, but a considerable percentage filters into the soil. This subsurface runoff is especially important in the barchan areas, where the water filters into the loose sand and gathers in lens-shaped deposits of freshwater on top of salty underground water. These deposits are more likely to form in overgrazed areas: the less vegetation there is, the smaller the amount of water lost by transpiration.
Much of the reserve is occupied by fields of barchan dunes, with ridges of mobile dunes up to several hundred meters long. There are also dunes that are fixed or half-fixed by the plant cover. These dune fields--with pairs, groups, and chains of barchans--are only present in the areas where the wind blows and there is a extensive covering of sand. The mobile dunes are continually changing. Their speed depends on their size and the nature of the surface over which they are moving. Small dunes generally move faster than large ones, as the transport of particles by the wind is slower in the large sandy areas. This means that the life of small dunes is also shorter: they either join with larger and slower dunes or disintegrate when they travel over wet surfaces such as takyrs and solonchaks.
In isolated barchans, the very dry sand is constantly being redistributed, but in the fields of barchans, the slower movement of the sand means that less water is lost by evaporation. In addition, the winter rains form lens-shaped freshwater deposits in the intermediate layers. The lower mobility and higher water content of the dunes in the fields of barchans mean that they can be colonized by pioneer plants that stabilize the sand even more. The dunes are eventually fixed, but during the long periods of little or no rain, the plants die and the sand becomes mobile again and joins the neighboring barchans.
This process has accelerated in the last few years due to the presence of grazing livestock. The sand of the stable dunes becomes mobile because 1) the plant cover is no longer continuous, and 2) the animals' hooves break the compact sands. The areas surrounding many of the former wells for watering animals in the reserve have turned into fields of barchans. The plants that grow on these new immobile barchans--the grasses Aristida karelinii and A. pennata and the milk vetch Astragalus chivensis (Leguminosae)--do not appeal to the livestock and so the herders have to move to other sites in the reserve.
The flora of the Karakum is perhaps the most interesting of all the cold-temperate deserts, as the woody species include many arboreal types. Since the Tertiary, the plants of the deserts of middle Asia, including the Karakum, have evolved in some degree of isolation and under conditions of extreme aridity, and this has given rise to an unusual flora with a very high percentage of endemic species. The plants are well adapted to moving sands and to underground water with a high content of salts. The first plant to colonize the mobile dunes is the grass Aristida karelinii, which is very similar to other species of the same genus that grow in the Namib Desert in southern Africa. Its roots are covered in small hairs to which sand grains adhere; this stabilizes the dunes and allows other plants to grow, among them Heliotropium arguzoides (Boraginaceae) and Tournefortia sogdiana (Boraginaceae). The smaller A. pennata grows on the smaller dunes of the fields of barchans and is a sign of overgrazing.
On the upper part of the dune, where the sand is still mobile, the most important tree is the sand acacia Ammodendron connolyi, which can reach a height of 30 ft (9 m) and whose extensive horizontal root system allows it to make use of even the slightest rainfall. Like other trees and the subshrubs of sand deserts, it can continue growing if it is covered by sand. It compensates for the mobility of sand by producing new shoots and adventitious roots fromits trunk. Another woody plant that is an important stabilizer of dunes is the endemic Eremospartum flaccidum (Leguminosae).
When the mobility of the sand diminishes, more woody plants root in the shelter of the herbaceous plants. In the fixed sands, which cover much of the reserve (about 34%), white saxaoul (Haloxylon persicum) and the species that accompany it form dense patches of vegetation. This is the livestock's preferred fodder, as its tender new shoots grow rapidly. There are several different associations within this plant formation: on slightly moist sands, the saxaoul grows with Aristida pennata, and on fixed sands it grows with the clump-forming sand sedge Carex physodes (Cyperaceae). The latter is the most important clump-forming species; its long, far-spreading subterranean rhizomes can resist the dry summers and the cold winters. Known as ilak, it provides fodder for sheep in the dry season, as its leaves die in the month of May and persist until the following spring.
The deep depressions between dunes are dominated by the zaisan saxaoul (Haloxylon ammodendrum). In these areas, the water table is close to the surface, but the high evaporation from the sandy soil means that it is saline. The abundant saxaoul leaf-litter means the soil is rich in humus and nitrogen but is highly saline. Only a few halophilous species can grow--mainly tamarisks (Tamarix) and saltworts (Salsola), especially S. richteri and S. arbuscula, which may become subdominant. These shrubs, that may live for up to 100 years, are valuable fodder. They are widespread and may appear as scattered individuals or in groups of 400-500 individuals. Depressions of this type between dunes represent only 5% of the area of the reserve, but they are very important for the wildlife and livestock. Where the roots reach the water table, dense patches of vegetation form, providing shelter and food for sheep and camels. These are the areas where it is easiest to find the burrows of the great gerbil (Rhombomys opimus).
In the daytime, the Repetek Biosphere Reserve is extremely peaceful; not a single animal can be heard. As the temperature at the soil surface can reach 176[degrees]F (80[degrees]C), most animals shelter underground in their burrows, where the air is cooler and saturated with moisture. Twenty-one species of mammal live within the reserve, 23 species of reptiles are present, and there are 196 species of birds (including migratory species), 25 of which nest in the area. The small rodents and reptiles are the most abundant animals and are not much affected by human activities. The great gerbil and the long-toed ground squirrel (Spermophilopsis leptodactylus) are present almost everywhere. The agamid lizard Phrynocephalus interscapularis is the most common reptile and can reach a population density of 100 individuals/ha (1 ha=2.5 acres) in the stabilized sands with scattered vegetation where it lives. The middle Asian four-toed tortoise (Testudo horsfieldi) can be seen in the Haloxylon scrub, where it lays eggs in batches of 10-15, which may be eaten by carnivores. Some closely related species of saurians such as Eremias grammica, E. lineolata and E. script avoid interspecific competition by making use of different microhabitats and hunting techniques.
Large animals are only sporadic visitors to the reserve and belong to very few species. One of these visitors, the Persian gazelle (Gazella subgutturosa) is one of the seven species found within the reserve that is in danger of extinction. It can be seen from October to March in the depressions between dunes, where it finds food and shelter. Carnivores are very rare in the Repetek, except for the marbled polecat (Vormela peregusna), presumably because of the lack of places to drink water. The wolf (Canis lupus), the sand cat (Felis margarita), and the caracal (F. caracal) can be seen in the mobile sands near the patches of saxaoul, where there are many birds' nests. The most frequent predators in the reserve are the carnivorous reptiles. The most spectacular is the desert monitor lizard (Varanus griseus), which is seen relatively easily. (It is in danger of extinction.) It feeds on birds eggs and the eggs of other lizards and hunts young rodents by lying in wait in their underground burrows. This is how the carnivorous snakes (the endemic boas Eryx miliarus and Thaphlometopon lineolatum) in the reserve hunt.
The rodents are the best represented vertebrate group in the Repetek Biosphere Reserve. These small mammals are of tremendous ecological importance and help explain one of the many natural interactions in the desert environment. When digging, the rodents redistribute the surface layers of the soil and sand, especially the seeds and fruits; this helps to spread the plants. Each species has its own food requirements, thus preventing a single species of plant from becoming dominant. The desert rodents have many predators, among them the weasel (Mustela nivalis), the marbled polecat (Vormela peregusna), and the common fox (Vulpes vulpes). The gerboas are the rodents that have adapted best to the immobile sand dunes in the Repetek and are represented in the reserve by three species, Dipus sagitta, Paradipus ctenodactylus, and Lichtenstein's gerboa (Jaculus lichtensteini). Gerboas have very sensitive hearing, a very good sense of smell, and show great agility when escaping their predators.
Most rodents are nocturnal. Those that are active during the daytime emerge only to feed in the early morning and late evening. Gerbillinae such as the great gerbil (Rhombomys opimus) and Meriones erythrourus and M. meidianus live in areas of fixed sands dominated by sedges. The rare porcupine Hystrix indica hirsutirostris lives in dense patches of Haloxylon ammodendrum, which are also home to the common mole-vole (Ellobius talpinus). The long-toed ground squirrel (Spermophilopsis leptodactylus) is very common in areas where fruits of Calligonum are found.
Both summer and winter are difficult for the rodents. Many rodents and some reptiles retire to their burrows to hibernate when the first frosts arrive. Most reptiles remain inactive through the dry summer. The severe water regime also affects the breeding period of the animals. The rodents of the Karakum only breed in a short period in the early spring, though they may produce abundant offspring. The female great gerbil (Rhombomys opimus), for example, can produce two or three litters in this short period.
Management and problems
The strictly protected central zone of the Repetek Biosphere Reserve has been affected only minimally by human impact, but the effects of grazing are clearly visible in the peripheral experimental zones. The livestock, mainly camels and karakul sheep, has a different effect on the ecosystem from the wild animals. Herds of domesticates travel much more slowly, and their grazing is much more selective. The grazing load is concentrated around the water holes, leading to destruction of the plant cover and sometimes the formation of fields of barchans. In other sites, however, the grazing is not sufficiently used. There are concentric strips of vegetation around the water holes, with the most degraded in the center.
Within the reserve, an experimental area has been fenced off, and studies have begun to determine the optimum level of grazing, depending on the plants and soil type present. These studies have led to the conclusion that the effects of grazing are not entirely negative and that banning grazing would be even more negative for the wild animals. The animals' hooves also play an important ecological role in the desert by 1) breaking up the soil surface (and thus preventing it from becoming compacted), 2) dispersing and burying seeds, and 3) fertilizing the soil with their dung. If there are too many animals, the vegetation is degraded, mainly because the soil is left so loose that the wind can blow it away. If there are too few animals, the soil becomes compacted and a moss cover grows, thus preventing seeds from getting buried in the soil (and the rodents and birds then eat them).
In the years when rodent populations are high, their excessive density is a major problem for the reserve staff who deal with the shepherds. In some areas, the rodents consume as much as 75% of the edible material, meaning that the herders have to keep their herds in movement all the time. Some areas are grazed twice a year and have little time to recover. Experts have suggested undertaking total protection for some of the carnivores in the reserve (foxes, wild cats), as they help to keep down the rodent populations. Many shepherds doubt if this would work, and they are concerned that the carnivores would attack their livestock.
Scientific exploration of the Karakum Desert began in 1912, when a scientific station was built next to the railway station in Krasnovodsk in Samarkand. The first research conducted was into the dynamics of the sand desert ecosystem and the drawing up of an inventory. But since a long canal was built from the Amu Dar'ya on the southern edge of the Karakum to the Caspian Sea, research has intensified and become more specialized. Since 1975, it has played an important role in UNESCO's MAB Program. The former Sand Desert station has become the Desert Research Station of the Turkmenistan Academy of Sciences. It is connected with the nearby town of Chardzhou by road and rail and is available for use by the research teams.
The core protected zone of the Repetek Biosphere Reserve consists of an untouched area of the desert and includes the main forms of the Karakum's relief (mobile sands, fixed dunes), as well as the most representative plant and animal species. The only research that has been performed in this area has been scientific study of the Karakum's most typical ecosystems, especially the barchans and their sparse vegetation of black saxaouls and white saxaouls. In the peripheral experimental area, there have been studies into the seasonal dynamics of the desert, the different soil types, phenology, successional changes in the plant cover, and animal distribution.
In the last few years, most research has been into the increasing influence of humans. Studies have also been conducted on more efficient ways of using the reserves's resources; these studies examine plant reproduction, forestry management, water extraction, the impact of felling shrubs, the effects of grazing by sheep and camels, and stabilization of mobile dunes. One particular research project focuses on the artificial production of the lens-shaped deposits of freshwater that form spontaneously under some barchans and thus provide water for the livestock. In the depressions between the dunes, the wind takes the sand to the lower, wetter layers of the takyrs.
After the winter and spring rains, the water flows into these depressions, forming small pools. As the takyr is impermeable, the water remains in the depressions until it evaporates. If a well were to be dug in the clay to a depth of just 10 ft (3 m), the water in the depressions would filter in and be above the layer of underground water. The only disadvantage is that it would be necessary to dig a line of wells to compensate for the movement of the dunes and the underground water. The zone would also need to be free from vegetation to prevent the formation of new dunes and to prevent the rainwater from being lost through transpiration by the plants.
248 Magnificent natural arches decorate the Arches Natural Park in Utah (United States). This is one of the various protected areas in the cold deserts, not all that extensive or numerous, that attempts to preserve the fragile ecosystem of this biome. The Arches National Park is situated in a region with abundant gorges and is well known for the arches that give it its name. They have been carved by erosion over millions of years from sandstone rocks deposited about 150 million years ago on top of the salt deposits occupying the vast desert. When the salt layers dissolved, the sandstone collapsed; since then it has been worn away to form a labyrinth of vertical blocks of stone. Sections of these thin rock walls fell from time to time, creating spectacularly shaped rock formations. There are almost 1,000 stone arches in the national park (see also photo 177), but this is not the only formation created by erosion. Pinnacles, needles, pillars, bridges, and many other forms have been shaped under the cloudless blue sky of Utah.
[Photo: Tom Hill / Auscape International]
249 The Gobi National Park was created in 1975 and protects a significant part of the Gobi Desert. The park is located in the Republic of Inner Mongolia and covers 13,096,532 acres (5,300,000 ha), making it one of the largest protected areas on the planet. Apart from desert proper, the park contains other very different environments such as the very green areas of the southerly stone desert. Knowledge of the Gobi's geological history is incomplete, but it seems that the string of lakes running between the Altai Mountains and the Hangayn Nuruu Massif formed at the end of the Tertiary, when the ancient sea that occupied the zone dried up. The sea's retreat to the west was followed by a continuous process of desiccation, which led to the gradual shrinking of the large lakes. This, in turn, gave rise to saline zones with surface deposits of sodium sulphate and sodium chloride. For this reason, the vegetation of the Gobi consists largely of plants that are resistant to salinity.
[Photo: Joel Bennett / Survival Films / Oxford Scientific Films]
250 The landscape of the petrified forest of Bosque Petrificado National Monu-ment in Santa Cruz province, Argentina. One of the most important fossil deposits in Argentina, it covers an area of 24,710 acres (10,000 ha), containing very rich remains of a Cretaceous dinosaur fauna and petrified forest of enormous Mesozoic Arau-caria trees (showing that this area must have had a moist subtropical climate for much of the Mesozoic). These fossils were preserved by volcanic action that covered and protected the plant remains and, in part, gave rise to the soils of present-day Patagonia (see photo 194).
[Photo: John Waters / Planet Earth Pictures]
251 The biosphere reserves in the cold deserts and subdeserts (1998). The accompanying figures show the areas (in hectares; 1 hectare =2.5 acres) and the year they were designated. Though the cold desert biome encompasses a large area, it contains only seven biosphere reserves. They cover a relatively small area, about 20,410,821 acres (8,260,000 ha), which represents less than 1% of the total area. There are five biosphere reserves in central and middle Asia (two in Iran, one in Mongolia, one in Turkmenistan, and one in China) and two in the Americas (one in North America and one in South America). The largest is the Gobi Desert Biosphere Reserve in Mongolia, which covers more than five million hectares. The smallest is the Desert Experimental Range in Utah (United States), which covers 49,421 acres (20,000 ha).
[Drawing: IDEM, based on data from UNESCO's MAB Program]
252 The Wah Wah Range, shown in the background, surrounds an area of the Great Basin in the United States. The area was declared a biosphere reserve not to protect its biological diversity or natural riches, but to prevent overgrazing. Overgrazing would no doubt ruin any possibility of recovering, or at least maintaining, the pastures of the Great Basin, which begin just at the base of the Wah Wah Range. As is typical of high areas with canyons, open forests of Juniperus are common there.
[Photo: Larry Minden / Minden Pictures]
253 The low winter temperatures in the deserts of Utah (United States) mean that the limited precipitations fall as snow. The photo shows the rabbitbrush Chrysotham-nus nauseosus (Asteraceae) that is found throughout southwestern North America. The region's high altitude is largely responsible for the low average annual temperatures and for the cold winters with abundant snowfall, to which the various plant communities have had to adapt. Most of the precipitation falls at a time when evaporation is very low; thus, much of the moisture can be used by the plants.
[Photo: Jim Brandenburg / Minden Pictures]
254 The western rattlesnake (Crotalus viridis) is one of the eight species of reptile that occur in the Badlands National Park in South Dakota (United States). It can be recognized by its light brown coloration (which reflects the heat), with irregular bands, and by the rattle of horny segments, as found in all rattlesnakes. The pits between the eyes and nose are sensitive to changes in temperatures; western rattlesnakes are capable of detecting changes of just a fraction of a degree (0.2[degrees]C). This allows them to recognize approaching prey; by comparing the information supplied by each pit, the snakes can figure out their preys' exact position.
[Photo: D. Scott / Natural Science Photos]
255 The Fremont or Sevier culture has left various archeological remains, includ-ing stone and bone tools and small clay figures, like the one in the photo, which is about 4 in (10 cm) tall and 3,000 years old. Finds like this have made it possible to reconstruct the lifestyle of these Pueblo Indians. They were herders and agriculturalists who were well adapted to the dry environment of the Great Basin. The Sevier culture died out, but the other Pueblo Indians such as the Shoshone, Ute, and Paiute survived.
[Photo: Utah Museum of Natural History / Werner Forman Archive]
256 Extraction of potassium chloride by evaporation in pools, in Moab, near Arches National Park in Utah (United States). This is one of the economic activities carried out in the desert areas of the Colorado Plateau. Most industry in the desert is based on mineral extraction, as the biome does not offer many other opportunities. The availability of large areas without plant cover (that are not privately owned) has favored this type of large-scale extraction, which often gives rise to serious environmental problems.
[Photo: Francois Gohier / Ardea London]
257 The Repetek area has been protected since 1928 and covers 85,498 acres (34,600 ha). It is largely occupied by stable ridges of sand, valleys between the dunes, and areas of mobile dunes. The wind blows the loose surface sands, while the more stable strata erode more slowly. In both cases, the sand grains are blown short distances, forming several different types of dunes, including low sand hills and ridges, individual barchans, and fields of barchans. The mean annual precipitation in this sandy environment is 4.5 in (114 mm) but varies greatly. The temperature changes greatly from season to season. The temperature may fall to values as low as those in Siberia--in January 1969, it went down to -24[degrees]F (-31[degrees]C)--while the summers are very hot, with a recorded maximum of 122[degrees]F (50.1[degrees]C) in July 1983. The extreme aridity of the Repetek area means there is a large moisture deficit, even in the years when winter snowfall is abundant, as evaporation is intense. Surprisingly for such conditions, many species have been recorded in the area of the Repetek Reserve, about 1,000 species of insects, 23 species of reptiles, 196 species of bird, 21 species of mammal, and 211 species of vascular plant. All of them are well adapted to shortage of water.
[Photo: Vadim Gippenreiter]
258 The flowering period in Repetek is short, but spectacular. The ephemeral species and geophytes make good use of the best conditions (see also photo 182). Along with the tulips, which are very abundant, the first species to flower include poppies (Papaver); they are followed by a succession of other species, starting with the blue flowers of Malcolmia, then the white daisy flowers of Leucanthemum, purple irises (Iris), and a wide range of foxtail lilies (Eremurus).
[Photo: Rodger Jackman / Oxford Scientific Films]
259 The desert monitor (Varanus griseus) is the largest and most robust reptile in central Asia, and by far the most impressive. The adults weigh up to 5.5 lb (2.5 kg) and can reach a length of 5.2 ft (1.6 m). The desert monitor has a mouth like a crocodile and can deal a powerful blow with its tail. Despite its ungainly appearance, it can catch a fast-running rodent and keep it immobile until swallowing it. When it has grown larger, it uses a gerbil burrow as a home base for hunting operations and may move up to half a kilometer away from it. It readily takes on snakes--not even the spines of hedgehogs discourage this reptile. It eats tortoises, birds' eggs, and all sorts of rodents voraciously and rapidly.
[Photo: Petr Velensky / Planet Earth Pictures]
260 Allium cristophii, shown in the Repetek Bio-sphere Reserve in Turk-menistan. This is one of a dozen species of onion (Allium) that grow in the deserts of central Asia. The number of plants is also high, and in Kazakhstan densities of 8,000 plants per hectare (1 hectare=2.5 acres) have been recorded. They grow on loess and on sandy soils, which they help to stabilize. Onions are ephemeroid geophytes that sprout and flower in the few months of spring and spend the rest of the year as underground bulbs. These bulbs are an important food source for rodents such as ground squirrels, which detect them by their strong smell, dig them up, and eat them, leaving only a small hole in the sand.
[Photo: Vadim Gippenreiter]
261 Fields and ridges of barchan dunes, like this one near Chardzhou, are typical landscape formations in the Repetek in the Karakum Desert. They are formed when the largest symmetrical undulations become asymmetrical and adopt the typical profile of a barchan dune, with a steep slope on the leeward side. These barchans then form pairs or groups that end up creating dune ridges perpendicular to the predominant winds. In the Karakum Desert, the wind direction is determined by the Pamir-Alai Range; in summer it is from the northwest toward the mountains, and in winter it blows from the southeast. Winds also blow from the north and northeast, so the movement of the dunes is pendular, clearly moving to the northwest. The shape and arrangement of the dune ridges also depends on the size of the sand grains, which are continuously redistributed in the individual barchans. In the barchan fields and ridges, water from the winter rains is retained in the intermediate strata. This means that reserves of freshwater form under the bare dunes but not under those with plant cover, as the plants use the water. The possibility of using these water reserves has been one of the main research areas in the Repetek in the last few years.
[Photo: Tom Ang / NHPA]
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|Publication:||Encyclopedia of the Biosphere|
|Date:||Apr 1, 2000|
|Previous Article:||4 Protected areas and biosphere reserves of the hot deserts and subdeserts.|