In the European Alps the importance of forests as protection against ava- lanches and soil erosion is becoming ever clearer with the continuing increase in population and development of tourism. The protective potential of the moun- tain forests can currently only be partially realised because a considerable propor- tion of high-altitude stands has been destroyed in historical times by man's extensive clearing ofthe forests. The forests still remaining are of limited effec- tiveness, due to inadequate density of trees and over-maturity. Considerable efforts, however, are now being made in the...

Root research under natural field conditions is still a step-child of science. The reason for this is primarily methodological. The known methods are tedious, time- consuming, and the accuracy of their results is often not very great. Many research workers have been discouraged by doing such root studies. The need for more information on the development and distribution of plant roots in different soils under various ecological conditions is, however, obvious in many ecological disciplines. Especially the applied botanical sciences such as agriculture, horticulture, and forestry are...

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 the spring of 1969 a small meeting was convened at the CSIRO Riverina Laboratory, Deniliquin, New South Wales, to discuss the biology of the genus Atriplex, a group of plants considered by those who attended to be of profound importance both in relation to range management in the region and as a tool in physiological research. The brief report of this meeting (Jones, 1970) now serves as a marker for the subsequent remarkable increase in research on this genus, and served then to interest the editors of the Ecological Studies Series in the present volume. This was an exciting time in plant...

This book examines the ecological characteristics of tropical savanna- most simply defined as those ecosystems which lie between the equatorial rainforests and the deserts and semi-deserts of Africa, Australia and South America. These savannas form a continuum of physiognomic types ranging from closed woodlands with a heliophytic grass understorey, through open savanna woodlands to treeless edaphic grasslands. In all areas Kranz syndrome or C4 grasses dominate the herbaceous layer while the woody component, at the moist end of the moisture gradient, comprises fire tolerant trees and shrubs....

The theory of ecological convergence underlies the biogeographers' maps of world biome-types. It also determines the degree to which ecological principles, derived from research on particular populations, communities or ecosystems, are generally valid, and hence also to what extent resource management principles are general. To quote Di Castri and Mooney (1973): "In effect, in order to assess the transfer of technology, it is essential to know to what extent information acquired from studying one particular ecosystem is applicable to another ecosystem of the same type but situated in a...

This is a stimulating tale of the interplay of observation, experimentation, working hypotheses, tentative conclusions, niggling and weightier doubts and great aspirations, on the part of some score of students, on varied ecological and other aspects of the regime and role of fire in relevant biomes and ecosystem- mainly in South Africa - and on other pertinent features of fire ecology. The impressive contents is a tribute to conveners and authors alike. One can expect a profound range and depth ofinvestigation and interpretation, a closeknit fabric of knowledge, delicately interwoven with...

The importance of irrigation in the world's agriculture is rapidly increasing. Although it is practised on a large scale mainly in arid and semi-arid zones, supplementary irrigation is becoming popular in semi-humid regions as well. The record of irrigation speaks for itself in terms of increased crop production. However, the question remains as to how permanent the achievement may be. Judging from history, it seems that irrigation eventually failed in many regions because the knowledge and technology available to society at the time were incapable of coping with the problems created....

Photochemical oxidants are secondary air pollutants formed under the influence of sunlight by complex photochemical reactions in air which contains nitrogen oxides and reactive hydrocarbons as precursors. The most adverse components formed by photochemical reactions in polluted air are ozone (0 ) 3 and peroxyacetyl nitrate (PAN), among many other products such as aldehydes, ketones, organic and inorganic acids, nitrates, sulfates etc. An analysis and evaluation of the available knowledge has been used to characterize the relationships among emissions, ambient air concentrations, and effects,...

WOLFGANG E. KRUMBEIN In this section we deal with special aspects of the Gavish Sabkha, and in two contributions with the very similar environments of the Ras Muhammad Pool (Chap. 10) and the Solar Lake (Chap. 15). Comparisons are made, however, in the individual contributions to other evaporative systems. Much ofthe work was stimulated by our late friend Eli Gavish during his pro ductive years of sedimentological studies along the shores of the Gulf of Elat. An other stimulus was initiated by the agreement that the Solar Lake and the Gavish Sabkha were selected as model cases for a Project...