Soils have been called the most complex microbial ecosystems on Earth. A single gram of soil can harbor millions of microbial cells and thousands of species. However, certain soil environments, such as those experiencing dramatic change exposing new initial soils or that are limited in precipitation, limit the number of species able to survive in these systems. In this respect, these environments offer unparalleled opportunities to uncover the factors that control the development and maintenance of complex microbial ecosystems. This book collects chapters that discuss the abiotic factors that structure arid and initial soil communities as well as the diversity and structure of the biological communities in these soils from viruses to plants.

Management of Problem Soils in Arid Ecosystems examines the challenges of managing soils in arid and semiarid regions. These soils contain low organic matter, are not leached, and accumulate lime, gypsum, and/or soluble salts, requiring special management and practices. This book discusses how to identify problems, reclaim the soils, and then use them efficiently and economically. Water management and desertification in these areas are also discussed. It contains extensive references as well as 40 tables and illustrations.

This volume summarizes our current understanding of biological soil crusts (biocrusts), which are omnipresent in dryland regions. Since they cover the soil surface, they influence, or even control, all surface exchange processes. Being one of the oldest terrestrial communities, biocrusts comprise a high diversity of cyanobacteria, algae, lichens and bryophytes together with uncounted bacteria, and fungi. The authors show that biocrusts are an integral part of dryland ecosystems, stabilizing soils, influencing plant germination and growth, and playing a key role in carbon, nitrogen and water cycling. Initial attempts have been made to use biocrusts as models in ecological theory. On the other hand, biocrusts are endangered by local disruptions and global change, highlighting the need for enhanced recovery methods. This book offers a comprehensive overview of the fascinating field of biocrust research, making it indispensable not only for scientists in this area, but also for land managers, policy makers, and anyone interested in the environment.

In arid lands, where vegetation is sparse or absent, the open ground is not bare but generally covered by a community of small, highly specialized organisms. Cyanobacteria, algae, microfungi, lichens, and bryophytes aggregate soil particles to form a coherent skin - the biological soil crust. It stabilizes and protects the soil surface from erosion by wind and water, influences water runoff and infiltration, and contributes nitrogen and carbon to desert soils. Soil surface disturbance, such as heavy livestock grazing, human trampling or off-road vehicles, breaks up the fragile soil crust, thus compromising its stability, structure, and productivity. This book is the first synthesis of the biology of soil crusts and their importance as an ecosystem component. Composition and functioning of different soil-crust types are discussed, and case studies are used to show the impact of crusts on landscape hydrology, soil stability, nutrient cycles, and land management.

This volume provides a comprehensive coverage of the principal extreme soil ecosystems of natural and anthropogenic origin. Extreme soils oppose chemical or physical limits to colonization by most soil organisms and present the microbiologist with exciting opportunities. Described here are a range of fascinating environments from permafrost to Martian soils. The book includes chapters on basic research in addition to applications in biotechnology and bioremediation.

THE ARID REGIONS; SOIL CLASSIFICATION; CHARACTERISTICS OF ARID-REGION SOILS; AFRICA; ASIA; AUSTRALIA; NORTH AMERICA; SOUTH AMERICA; SPAIN; CHEMICAL PROPERTIES; PHYSICAO PROPERTIES; BIOLOGICAL PROPERTIES.

Soils formed or now existing under arid climatic conditions cover more than one-third of the world's land surface. Many have unique characteristics which can pose difficult geotechnical problems. This text considers these problems and suggests ways of overcoming them.