The biology of African savannahs

279 Pages·2007·4.22 MB·English

by  Bryan Shorrocks

The Biology of African Savannahs
THE BIOLOGY OF HABITATS SERIES
This attractive series of concise, affordable texts provides an integrated
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ies which are possible. Management and conservation issues are also
included.The series is intended for naturalists,students studying biological
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professional biologists embarking on research in a new habitat.
The Biology ofRocky Shores
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The Biology ofPolar Habitats
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The Biology ofLakes and Ponds
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The Biology ofthe Deep Ocean
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The Biology ofLakes and Ponds,Second ed.
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The Biology ofSoil
Richard D.Bardgett
The Biology ofFreshwater Wetlands
Arnold G.van der Valk
The Biology ofPeatlands
Håkan Rydin and John K.Jeglum
The Biology ofMangroves and Seagrasses
Peter Hogarth
The Biology ofAfrican Savannahs
Bryan Shorrocks
The Biology of
African Savannahs
Bryan Shorrocks
Environment Department
University ofYork
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© Bryan Shorrocks 2007
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First published 2007
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Typeset by Newgen Imaging Systems (P) Ltd.,Chennai,India
Printed in Great Britain
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ISBN 978–0–19–857065–3 978–0–19–857066–0 (pbk)
10 9 8 7 6 5 4 3 2 1
For Jo,who also loves Africa
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Preface
This book is an introduction to African savannahs and their biology,
concentrating on large mammal ecology, behaviour and conservation.
Although it is a book on savannahs I hope that it sets out its ideas within a
general framework of ecological and behavioural ideas.
In my 40 years as an ecologist I have worked on both temperate and tropi-
cal terrestrial ecosystems.I have carried out field surveys,field experiments
and built mathematical and computer models.I believe all these elements
are essential for understanding Nature,and they all appear in this book.You
cannot simply watch wildlife populations and communities in order to
understand how they function. You have to employ field manipulations,
either natural or artificial,to tease out the possibilities.You have to describe
what you see not just in words but in mathematical models,to allow your
less precise verbal suspicions to be tested.And savannah ecology must fit
comfortably within the framework ofgeneral ecological ideas.There can be
no special pleading or special mechanisms that other ecologists just don’t
understand.I have tried to present such an encompassing view ofsavannah
ecology and behaviour.
African savannahs are magical places. The brightness of the light, the
intensity ofthe colours,and the beauty and excitement ofthe wildlife,and
of course the people. These savannahs are worth preserving for future
generations and I hope,in a small way,this book will generate an interest
that helps them survive.
I would like to thank all the people that have helped in my savannah
work in East Africa,in particular the people at the Mpala Research Centre,
in Laikipia,Kenya.Their help and insights have been invaluable during my
frequent stays there. Finally my thanks to Paul Ward who, over several
beers,over several nights,while running an undergraduate field course in
Derbyshire reawakened my latent interest in Africa and its wildlife.
Bryan Shorrocks
June 2007
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Contents
1 Savannahs 1
Distribution world-wide 2
African savannahs 10
2 The vegetation 29
Rainfall,plant biomass,and the grass–tree mixture 29
Morphology and life history 32
Grasses 40
Trees 43
Local vegetation patterns:the Serengeti–Mara ecosystem 57
3 The animals 64
The insects 64
The birds 66
The mammals 68
4 Single species populations 113
Estimating numbers 114
What changes numbers? 127
Population models 136
Other species,in other areas 141
5 Species interactions 155
Predator–prey type interaction ((cid:1) (cid:2)) 156
Competitive interactions ((cid:2)(cid:2)) 180
Mutualistic interactions ((cid:1)(cid:1)) 196
6 The savannah community and its conservation 205
Energy flow and food webs 206
Assembly rules 219