The directives of the Twenty-Third Congress of the Communist Party of the Soviet Union concerning the Five-Year Plan for the Development of the National Economy of the USSR for 1966-1970 stipulated that the average annual output of agricultural products should increase by 25 percent compared with the average annual production achieved during the previous five-year period. To ensure the steady development of animal husbandry, the directives prescribed a number of measures, including increasing the productivity of natural forage lands and expanding improved artificial pastures. The successful development of pastoral livestock husbandry and the increase of its productivity are possible only when a stable fodder base has been established. Over the past decade, numerous scientific and production organizations in Uzbekistan have been conducting extensive research and experimental work in this field. Participants include the Institute of Botany of the Academy of Sciences of Uzbekistan, the All-Union Karakul Sheep Research Institute, the Uzbek Research Institute of Animal Husbandry, Lenin Tashkent State University, the Uzbek State Institute for Land Planning and Design, the Uzbek Forestry Research Institute, and the Pasture Improvement and Development Trust of the Ministry of Agriculture of Uzbekistan. In the central Kyzylkum Desert, oasis agriculture based on artesian irrigation has been developing successfully. The Pasture Improvement and Development Trust has transferred approximately 1,500 hectares of reclaimed and improved land to agricultural enterprises. Collective farms in Bukhara Oblast have successfully cultivated alfalfa, sorghum, maize, Sudan grass, melons, and vegetable crops on these lands. Large areas of planted forests and shrublands have appeared on newly irrigated lands, and new settlements have emerged. In order to increase the productivity of desert pasturelands through afforestation, improve impoverished plant communities, and establish shelterbelts for pasture protection, extensive studies are being conducted on the biology, physiology, and ecology of the most valuable pasture plants. Significant achievements in this field have been made by the Institute of Botany of the Academy of Sciences of Uzbekistan, the All-Union Karakul Sheep Research Institute, and the Uzbek Research Institute of Animal Husbandry. The achievements of pasture agrometeorology should not be excluded from the process of solving these important problems. Agrometeorological indicators obtained through the statistical analysis of extensive observations of pasture plant growth and development can be used in plant improvement programs and in addressing the complex issue of selecting plant components for the enhancement of degraded vegetation communities and the creation of new ones. The application of methods for evaluating existing agrometeorological conditions and forecasting expected agrometeorological conditions makes it possible to utilize correctly the bioecological characteristics of pasture plant development in order to implement large-scale vegetation improvement programs across the plains, foothill zones, and mountain slopes of the Central Asian republics. Hydrometeorological services also form an essential component of the rational organization of pastoral livestock husbandry, and the demand for such services is increasing every year. One form of this support is agrometeorological service for pastoral livestock production. This includes, first, the provision of information and warnings concerning adverse weather phenomena during the principal periods of livestock-production activity; second, the agrometeorological assessment of existing conditions affecting pasture vegetation growth; and finally, long-range forecasts of agrometeorological conditions governing the development, growth, and yield formation of pasture vegetation for specific natural-geographical regions and local production administrations. The essence of agrometeorological evaluation and forecasting lies in determining the qualitative and quantitative relationships between the development, growth, and productivity of pasture plants and the meteorological conditions prevailing during the growing season. However, the primary difficulty in solving these problems is the lack of long-term, high-quality phenological and plant-yield records corresponding to meteorological observations. This deficiency, in turn, arises from the complexity of observing the diverse plant forms that grow in the deserts of Central Asia. Approximately 25 to 30 plant species constitute the principal forage and landscape-forming vegetation of desert pastures. These species belong to several botanical families and different economic groups and possess distinctive biological characteristics and diverse developmental cycles, factors that determine both the seasonal patterns and the varying degrees of their utilization by livestock. It is also known that individual plant species differ in their heat requirements (Lysenko, 1928) and in their responses to moisture conditions (Korovin, 1958). Consequently, it is necessary to take into account the specific biological and ecological features of each species, together with the rhythms and dynamics of its development associated with climate and zonal environmental phenomena. During the past two or three decades, Soviet geobotanists have repeatedly addressed the relationship between pasture vegetation development and the combined influence of meteorological conditions in studies devoted to the evaluation of pasture forage resources. Geobotanical investigations have generally described the qualitative aspects of plant developmental rhythms, established connections between pasture productivity and weather conditions, and used data from individual observation stations to reveal seasonal dynamics in pasture-plant yields. Particular attention should be given in this regard to the extensive work of Ye. P. Korovin and M. M. Savitskaya, as well as to the investigations conducted by I. S. Amelin, A. N. Bakhlenkov, and O. I. Morozova at the Nisha and Mubarak observation stations. At the Central Asian Hydrometeorological Research Institute (SANIGMI) and the Agrometeorological Forecasting Section of the Weather Service of the Hydrometeorological Administration of the Uzbek SSR, these methods have been widely applied and tested in operational services for pastoral livestock husbandry in Kazakhstan, Uzbekistan, and Turkmenistan. Individual studies in pasture agrometeorology have also begun in Kyrgyzstan and Tajikistan. The present study was carried out at the Central Asian Hydrometeorological Research Institute and is based on nine years of observations (1958-1966) collected during eleven agrometeorological expeditions conducted by the author in different regions of the Kyzylkum Desert on behalf of SANIGMI. Extensive use was also made of long-term observational records (7 to 13 years) from eight desert meteorological stations operated by the Hydrometeorological Administration of the Uzbek SSR. In addition, data from Kazakh and Turkmen meteorological stations located within or adjacent to the Kyzylkum Desert were utilized. The research also incorporated certain results from laboratory-field experiments on the sowing of ephemeral grasses conducted by the author during 1957-1962 at SANIGMI's experimental base, the Bozsu Agrometeorological Station. Doctor of Geographical Sciences A. P. Fedoseyev of the Kazakhstan Hydrometeorological Research Institute and Candidate of Agricultural Sciences G. G. Beloborodova provided important methodological assistance in this work. The mathematical processing of the materials was carried out under the guidance and with the direct assistance of S. M. Kozik. During the fieldwork of the expeditions, students of the Department of Geobotany and Plant Systematics of the Faculty of Biology and Soil Science at Lenin Tashkent State University, together with technical personnel from SANIGMI's Agrometeorological Section, participated on a regular basis. Beginning in 1962, P. A. An, a research worker of SANIGMI's Agrometeorological Section, took an active part in the expeditions and served as co-author of certain sections of Chapters Five, Six, and Seven. During the stationary agrometeorological investigations conducted by SANIGMI, substantial assistance was provided by the staffs of the Buzaubai Meteorological Station (director A. M. Kotov, 1958-1959) and the Akbaital Meteorological Station (directors G. N. Lvov, 1959-1961, and A. G. Koshelev, 1961-1963). Senior technician M. P. Filimonova of SANIGMI's Agrometeorological Section took an active part in conducting the laboratory-field experiments. T. N. Shakhova and L. A. Shestakova carried out extensive work in preparing and organizing the cartographic materials. The author expresses sincere gratitude to all the above-mentioned colleagues for the assistance and support they provided during the collection of field materials and the preparation of this monograph.