Steppes form one of the largest biomes. Drastic changes in steppe ecology, land use and livelihoods came with the emergence, and again with the collapse, of communist states. Excessive ploughing and vast influx of people into the steppe zone led to a strong decline in nomadic pastoralism in the Soviet Union and China and in severely degraded steppe ecosystems. In Mongolia nomadic pastoralism persisted, but steppes degraded because of strongly increased livestock loads. After the Soviet collapse steppes regenerated on huge tracts of fallow land. Presently, new, restorative steppe land management schemes are applied. On top of all these changes come strong effects of climate change in the northern part of the steppe zone. This book gives an up-to-date overview of changes in ecology, climate and use of the entire Eurasian steppe area and their effects on livelihoods of steppe people. It integrates knowledge that so far was available only in a spectrum of locally used languages.

A review of the developments in the various branches of vegetation science with special attention to the Dutch contributions compiled to celebrate the one-hundredth meeting of the Commission for the Study of Vegetation of the Royal Botanical Society of the Netherlands

Steppes form one of the largest biomes. Drastic changes in steppe ecology, land use and livelihoods came with the emergence, and again with the collapse, of communist states. Excessive ploughing and vast influx of people into the steppe zone led to a strong decline in nomadic pastoralism in the Soviet Union and China and in severely degraded steppe ecosystems. In Mongolia nomadic pastoralism persisted, but steppes degraded because of strongly increased livestock loads. After the Soviet collapse steppes regenerated on huge tracts of fallow land. Presently, new, restorative steppe land management schemes are applied. On top of all these changes come strong effects of climate change in the northern part of the steppe zone. This book gives an up-to-date overview of changes in ecology, climate and use of the entire Eurasian steppe area and their effects on livelihoods of steppe people. It integrates knowledge that so far was available only in a spectrum of locally used languages.

We have edited this book in honour ofMakoto Numata, the nestor of Japanese plant ecology, who will celebrate his 65th birthday in November 1982 and will be retiring from office in March 1983. As the main concern of his work during the last years was to educate people in ecological understanding - probably the only possibility for mankind to master the 'environmental problems' - the topic chosen for this book seemed the most suitable one to honour the retiree. We hope that this volume will prove to be useful for many in carrying through this important task of modern ecology. We are grateful to the authors and particularly to Mr. Peters and the staff of Dr. W. Junk publishers for their patient cooperation. We are also indebted to Jan Knaapen for making the index. Wien, Utrecht and Chiba, June 1982 The Editors VII Contents Preface.................................................................................................... VII List of contributors....................................................................................... XI A biography of Makoto Numata by I. Ikusima ........................................................ .

biological attributes of the three species according to the sequence in which they invade successively as a conse Studies on sample plots in Halimione portulacoides com munities show that environmental disturbances, either quence of environmental disturbance. It can therefore be concluded that for understanding this mechanism in the natural or induced by man, start a sequence of partly salt-marsh ecosystem a thorough study on the functioning overlapping density maxima in Suaeda maritima, Aster of these and other relevant biological attributes in the local tripolium and Puccinellia maritima successively, before the populations is essential. original Halimione community totally recovers. When Returning to the basic questions put in the introduction succession time before recovering is long enough, there are it is concluded that: tendencies in redundancy of this sequence stressing the unilinear character of the succession. Minor environmental a) There exist orderly and predictable succession patterns in the investigated salt-marsh vegetation. impacts induce a longer time-lag period of the Suaeda b) Following occasional disturbances, whatever these may density maximum, suggesting threshold values of these impacts for the species to maintain minimal population be, the vegetation recovers via a sequence of overlapping interim species populations showing a unilinear or obliga densities or to become locally extinct. This sequence of tory (Hom 1976) succession pattern."

Deserts provide a seemingly hostile environment in which plants can, nevertheless, survive and grow. This book, originally published in 1992, considers the ecological strategies adopted by desert succulents to overcome these problems. Much fresh data on the physiological ecology of succulent plants of southern Africa is presented - the results of more than ten years' work by the authors, both in the field and the laboratory. This information forms the basis for a better understanding of the water relations and carbon balance of succulents during short- and long-term drought and leads the authors to a definition of succulence as a tool for the temporary storage of water, essential for the conservation of physiological performance during times of drought. The authors conclude by providing a basic scheme in which the significant functional aspects of succulent life strategies are given, revealing the main trends in the biology of these fascinating plants.