12. Regeneration of woody legumes in Sahel.

Publ. of Botanical Institute, Aarhus, University in cooperation with DANIDA Forest Seed Centre, Denmark; ISBN 87-87600-35-8, 1991, 90 pp.

Woody legumes are a major feature of the semi-arid vegetation zones of West Africa and are very important economically in the region, but there is little published information on their natural regeneration. In this short book, Mr. Tybirk gives an overview of the regeneration strategies of 36 species found in West Africa's Sahelian and dry Sudanian zones.

Most of the legumes covered are indigenous, but the author also includes a few exotic species.

He discusses in separate chapters four phases in the natural-regeneration process - seed dispersal, seed predation, germination of hard-seeded plants, and growth of young seedlings. Based on the morphology of the diaspore, personal observations and the literature, he suggests that about 50% of the species covered are dispersed primarily by wind (hemi-legumes or samaras), nearly all species are dispersed either primarily or secondarily by passage through animals (most by ungulates and a few also by birds and/or primates), and a few species are secondarily dispersed by water.

The chapter on seed predation focuses mainly on predation by the beetle family Bruchidae, which has a major ecological and economic impact on woody legumes in the region. Lists of host-predator associations, host-predator-parasite associations, and seed-predation percentages are compiled from the literature.

The chapter on seed germination presents a general description of seed characteristics, dormancy-control mechanisms, seed banks in the soil, the germination process, and environmental factors affecting germination in the region. The chapter on seedling growth describes seedling development, vegetative regeneration, and environmental factors influencing growth.

The author emphasizes throughout the text that successful natural regeneration depends on complex ecological interactions involving dispersal, predation, germination, timing, grazing, fire, drought, soil type and other factors. He illustrates this complexity with many examples, some of which have important implications for ecosystem management. In the last two chapters, he discusses some general implications for long-term management and sustainable use of woody legumes in the region and provides a useful summary of regeneration characteristics for each species.

This book is a valuable contribution to our understanding of the natural regeneration of woody legumes in the Sahel. It should also stimulate further research in this important area.

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