This book is about the regeneration of plants from seed under field conditions. It attempts to give a reasonably balanced overview of the many aspects of this broad topic. The first chapter introduces some general ideas about reproduction in plants. Subsequent chapters deal with the early stages in the life of a plant, from ovule to established seedling, in a more or less chronological order. The final chapter shows how the data on regeneration requirements of different species can be used to explain a number of important characteristics of whole plant communities. The study of the ecological aspects of reproduction by seed touches on a range of issues of current interest in biology. A discussion of seed size and number involves a consideration of the concepts of resource allocation, life cycles and strategies. The in teractions between plants and animals seen in pollination, seed dispersal and predation provide excellent material for the study of coevolution. Investigations on regeneration from seed have greatly our understanding of the causes and maintenance of species added to diversity. The reader will find that virtually all the experiments and field observations described in this book are conceptually very simple. Many of them merely required numerous careful measurements.
Table of Contents1 Reproductive strategies in plants.- 1.1 Seeds versus vegetative reproduction.- 1.2 The principle of allocation.- 1.3 Reproductive effort.- 1.4 Life histories and fertility schedules.- 1.5 Seed size and number.- 2 Predispersal hazards.- 2.1 Seed losses due to pollination failure.- 2.2 Seed losses due to resource deficiency.- 2.3 Seed losses due to predation.- 2.4 Seed losses due to lethal gene combinations.- 3 Dispersal.- 3.1 Dispersal curves.- 3.2 Dispersal agents.- 3.3 Wind dispersal.- 3.4 External carriage by birds, animals and man.- 3.5 Myrmecochory.- 3.6 Dispersal by frugivory.- 3.7 Long distance dispersal.- 4 Soil seed banks.- 4.1 The seed content of soils.- 4.2 Seed banks in relation to life strategies.- 4.3 Seed longevity.- 4.4 Field longevity experiments.- 4.5 Ecological significance of seed banks.- 5 Dormancy.- 5.1 Ecological significance of dormancy.- 5.2 Types of dormancy.- 5.3 Cyclic changes in dormancy.- 5.4 Influence of parental environment on seed dormancy.- 5.5 Correlative effects.- 6 Germination.- 6.1 The role of gaps in regeneration.- 6.2 Temperature fluctuations.- 6.3 Light quality and periodicity.- 6.4 Microtopography and water relations.- 6.5 The chemical environment.- 7 Seedling establishment.- 7.1 Shade, seed size and seedling growth.- 7.2 Seedling morphology in relation to shade.- 7.3 Competition and seedling survival.- 7.4 Other establishment hazards: drought, burial and predation.- 8 Regeneration and diversity.- 8.1 Coexistence.- 8.2 Gap size.- 8.3 Gap diversity.- 8.4 Timing of disturbance.- 8.5 Environmental fluctuations.- 8.6 Intraspecific spacing.- 8.7 Relative abundance.- References.