Savannas are the most widespread ecosystem in the tropics and as such are subjected to great human pressure that may result in massive soil degradation.
The book addresses the role of species in the function of savanna ecosystems. It is shown that savannas are enormously diverse and that four factors determine the function of savanna ecosystems: Plant Available Moisture; Plant Available Nutrients; Fire; Herbivores.

This book contains the results of a Symposium on the physiological ecology of plants of the lowland wet tropics held in Mexico in June 1983 organized by the Instituto de Biologla of the National University of M"exico (U. N . A. M. ), and sponsored by UNAM, CONACYT, NSF and UNESCO (CIET). A workshop portion of the Symposium was held at the tropical research station at Los Tuxtlas, Veracruz. This Symposium originated in response to the increasing interest in the physiological ecology of tropical plants, because of the potential. of this field to provide a basic understanding of functioning of tropical plant communities. The study of physiological ecology of tropical plants has been delayed in some cases by the lack of conceptual framework, but also by the absence of appropriate instrumentation and techniques with which to conduct precise measurements under high temperature, high humidity field conditions. Hypotheses and concepts of the physiological ecology of tropical plants have been based mainly on observational data and the analysis of growth forms and leaf anatomf. The early work of A. F. W. Schimper and o. Stocker in Asia, and the extensive surveys made by H. Walter on the osmotic potentials of plants in the tropics and subtropics, constituted, until relatively recently, the only available information on the water and carbon relations of tropical plants.

The book represents a multidisciplinary approach to understanding soil–landscape–vegetation relationships and, specifically, the ecophysiology of plant communities developing on sandy soils of very low fertility that are subject to seasonal flooding. It provides an overview of the white sand ecosystems within the Amazon basin, and focuses on the forest and herbaceous (meadows) vegetation growing on the dystrophic sandy soils of the upper Negro and Orinoco river basins. Several chapters describe physiographic aspects of the study area using integrated remote sensing and in situ sampling. By doing so they attain a comprehensive description of the origin and evolution of soils and landscapes, an advanced classification of soils, and a mapping of the geographic distribution of psammophilous vegetation. This volume also provides a phytosociological classification of extensive forested areas, and a detailed description of the structure and diversity of little-known herbaceous formations.It targets professionals in the fields of ecology, ecophysiology, geomorphology, soils, vegetation, and the environmental sciences. The information it offers may be of significant use to researchers, protected area planners, and environmental policy makers.

Prolonged seasonal drought affects most of the tropics, including vast areas presently or recently dominated by 'dry forests'. These forests have received scant attention, despite the fact that humans have used and changed them more than rain forests. This volume reviews the available information, often making contrasts with wetter forests. The world's dry forest heterogeneity of structure and function is shown regionally. In the neotropics, biogeographic patterns differ from those of wet forests, as does the spectrum of plant life-forms in terms of structure, physiology, phenology and reproduction. Biomass distribution, nutrient cycling, below-ground dynamics and nitrogen gas emission are also reviewed. Exploitation schemes are surveyed, and examples are given of non-timber product economies. It is hoped that this review will stimulate research leading to more conservative and productive management of dry forests.