Biotic Interactions In Arid Lands

The exigencies of life in the desert environment have resulted in the se lection of a diversity of adaptations, both morphological and physiologi cal, in the flora and fauna. At the same time, many plants and most small animals are able not merely to exist but even to thrive under desert conditions - mainly by avoiding thermal extremes and by the refine ment of pre-existing abilities to economise in water. In the same way, the biotic interactions of the flora and fauna of the desert do not involve many new principles. Nevertheless, conditions in arid regions frequently do invoke refinements of the complex interrelations between predators and their prey, parasites and their hosts, as well as between herbivores and the plants upon which they feed. In this book, I shall discuss not only such interactions and their feedback effects, but also community processes and population dynamics in the desert. The physical conditions of the desert that principally affect predators and their prey are its openness and the paucity of cover. This is re stricted to scattered plants, occasional rocks, holes, and crevices in the ground. Furthermore, nightfall does not confer relative invisibility, as it does in many other ecobiomes, because of the clarity of the atmosphere. The bright starlight of the desert renders nearby objects visible even to the human eye, while an incandescent moon bathes the empty landscape with a flood of silver light. Consequently, adaptive coloration is func tional at all hours of the day and night.

This comprehensive account of arid-land ecosystems will be of importance to university teachers and professional ecologists throughout the world.

Arid lands require that organisms inhabiting them be well-adapted to thrive or even just to survive. This book provides a review of the ecological adaptations - be they behavioural, physiological or morphological - of carnivores to arid environments. Following a general introduction into aridity and arid lands in Africa, the major carnivore families are presented. Ecological adaptations of carnivores in arid lands reveal the amplitude and resilience of the ecology of these animals. In setting up conservation measures, the nature and extent of such adaptations are important facets in determining the effective area and degree of heterogeneity required as habitat by a carnivore population so as to produce a viable unit.

Encyclopedia of Deserts represents a milestone: it is the first comprehensive reference to the first comprehensive reference to deserts and semideserts of the world. Approximately seven hundred entries treat subjects ranging from desert survival to the way deserts are formed. Topics include biology (birds, mammals, reptiles, amphibians, fishes, invertebrates, plants, bacteria, physiology, evolution), geography, climatology, geology, hydrology, anthropology, and history. The thirty-seven contributors, including volume editor Michael A. Mares, have had extensive careers in deserts research, encompassing all of the world’s arid and semiarid regions. The Encyclopedia opens with a subject list by topic, an organizational guide that helps the reader grasp interrelationships and complexities in desert systems. Each entry concludes with cross-references to other entries in the volume, inviting the reader to embark on a personal expedition into fascinating, previously unknown terrain. In addition a list of important readings facilitates in-depth study of each topic. An exhaustive index permits quick access to places, topics, and taxonomic listings of all plants and animals discussed. More than one hundred photographs, drawings, and maps enhance our appreciation of the remarkable life, landforms, history, and challenges of the world’s arid land.

This volume emphasizes application of the basic ecological relationships among plants, animals, microorganisms, the physical environment and man to reconstruct wildland ecosystems. It contains the proceedings of a symposium sponsored by the American Association for the Advancement of Science.

Usually authors write introductions for their books, although they know that not many readers will read it. Despite this, authors insist on writing an introduction and no publisher will publish a book without one. I would like to inform my dear readers that I have spent almost all of the first quarter of my life in a village in the Nile Delta, 65 km north of Cairo. The everyday scenery there was the beautiful green landscape dissected with canals full of running water. All of these were bordered with the huge sycamore, mulberry and acacia trees. The desert was something unknown to me at that time, except for the very basic information given in geography books, which explained that the desert is a place without water or cultiva tion. Some of my ideas about the desert came to me from the stories in the history of Islam and the desert lands where Islam originated. My real attraction to the desert developed in the last year of my under graduate studies. This was during the field courses in Ecology (Prof. A.M.

Environmental and specific diversity in the Chihuahuan desert in general, and in the Cuatro Ciénegas Basin in particular, has long been recognized as outstanding. This book provides a global ecological overview, together with in-depth studies of specific processes. The Chihuahuan desert is the warmest in North America, and has a complex geologic, climatic and biogeographical history, which affects today’s distribution of vegetation and plants and generates complex phylogeographic patterns. The high number of endemic species reflects this complex set of traits. The modern distribution of environments, including aquatic and subaquatic systems, riparian environments, gypsum dunes and gypsum-rich soils, low levels of phosphorous and organic matter, and high salinity combined with an extreme climate call for a range of adaptations. Plants are distributed in a patchy pattern based on punctual variations, and many of them respond to different resources and conditions with considerable morphological plasticity. In terms of physiological, morphological and ecological variability, cacti were identified as the most important group in specific environments like bajadas, characterized by high diversity values, while gypsophytes and gypsovagues of different phylogenies, including species with restricted distribution and endemics.

Annual desert plant species of unrelated taxa in the Negev Desert of Israel have developed complementary sets of adaptations and survival strategies as ecological equivalents with physiological, morphological and anatomical resemblances, in the various stages of their life cycles. After 40 years of research in hot deserts Yitzchak Gutterman provides a comprehensive treatise of such adaptations and strategies. In doing so he covers the following topics: post-maturation primary seed dormancy, which prevents germination of maturing seeds before the summer; seed dispersal mechanisms with escape or protection strategies; cautious or opportunistic germination strategies; seedling drought tolerance. The day-length is an important factor in regulating flowering as well as the phenotypic plasticity of seed germination which is also affected by maternal factors.