Semi Arid Environments

The semi-arid zones of the world are fragile ecosystems which are being sub stantially modified by the activities of mankind. Increasing human populations have resulted in greater demands on semi-arid zones for providing human susten ance and the possibility that this may enhance desertification is a grave concern. These zones are harsh habitats for humans. The famines that resulted from drought during the late 1960's and the 1970's in the African Sahel illustrated the unreliability of present agricultural systems in this zone. Large fluctuations in ag ricultural production have occurred in semi-arid zones of Australia, North Ameri ca, and the Soviet Union due to periodic droughts, even though considerable ag ricultural technology has been devoted to agricultural development in these zones. The challenge to mankind is to manage these different semi-arid zones so that pro ductivity is increased and stabilized, and environmental deterioration is decreased. Irrigation can be used to increase and stabilize agricultural production in semi-arid zones as discussed in Volume 5 of this series, Arid Zone Irrigation. The present volume, Agriculture in Semi-Arid Environments, focuses on dryland farming in semi-arid zones, and is relevant to the large areas of the world where rainfall is limiting and where water is not available for irrigation. This volume is designed to assist agricultural development in these areas and consists of reviews and analyses of available information by scientists working in Africa, Australia, and at the U ni versity of California.

Arid and Semi-Arid Environments focuses upon major themes in the study of desert landscapes, processes and landforms. The book considers the physical causes of aridity, the desert hydrological cycle and the problems of water supply. Particular attention is paid to desert ecosystems and how they are related to aridity. A detailed study is made of the wide range of landforms which are unique to desert areas and how they were formed. Evidence in the landscape of past climates is examined in relation to the current debate on desertification.

Semi-arid climate regions receive low annual precipitation and intermediates between the desert climates and humid climates in ecological characteristics and agricultural potential. Semi-arid climates tend to provide scrubby vegetations in regions where they exist. There are two variations of the semi-arid climate, a hot semi-arid climate and a cold semi-arid climate. This book presents topical research data in the study of semi-arid environments, including the semi-arid environments of the El Melah Lagoon in Tunisia; improving reproductive outputs of small ruminants reared in semi-arid environments; the presence of cyanobacterial soil crusts in semi-arid ecosystems is associated with an increase in carbon and nitrogen sequestration; semi-arid vegetation in Brazil; and the semi-arid zone afforestation in northern Israel.

This book deals with arid and semi-arid environments and their classification, and the physiological restraints and adaptations of plants to the environment. Further, it discusses economic botany and the needs and methods of conserving economic plants. A broad view is taken regarding the definition of economic plants, taking into account their value to the environment as well as to man and to livestock. The individual deserts and associated semi-arid regions are described in separate chapters, providing background information on the regional environments in terms of climate and major plant formations. The economic plants within these formations, their usages, geographical distribution together with their morphological and physiological adaptations are treated in detail.

Offering a cross-country examination and comparison of drought awareness and experience, this book shows how scientists, water managers, and policy makers approach drought and water scarcity in arid and semi-arid regions of Spain, Mexico, Australia, South Africa and the United States.

This publication aims to contribute to planning and management approaches that minimize land degradation and desertification in arid and semi-arid zones as a result of extractive industries operations. Both operational and policy guidance are included to help those government departments responsible for the licensing, planning and monitoring of extractive industries activities to take account of environment and development issues in their decision-making.

The natural scarcity of water in arid and semiarid regions, aggravated by man-made factors, makes it difficult to achieve a reliable water resources supply. Communities in these areas pay the price for thousands of years of water manipulation. Presenting important insight into the complexities of arid region hydrology, Engineering Hydrology of Arid

Based on four decades of research by Professor Andrew Goudie, this volume provides a state-of-the-art synthesis of our understanding of desert geomorphology. It presents a truly international perspective, with examples from all over the world. Extensively referenced and illustrated, it covers such topics as the importance of past climatic changes, the variability of different desert environments, rock breakdown, wind erosion and dust storm generation, sand dunes, fluvial and slope forms and processes, the role of the applied geomorphologist in desert development and conservation, and the Earth as an analogue for other planetary bodies. This book is destined to become the classic volume on arid and semi-arid geomorphology for advanced students and researchers in physical geography, geomorphology, Earth science, sedimentology, environmental science and archaeology.