ABSTRACT
How Does Grasslands Diversity Vary in Space and Time? . . . . . . . . . . . . . . 46 What Determines the Number of Species That May Coexist and
Makes Some Grasslands Richer Than Others?. . . . . . . . . . . . . . . . . . . . . . 47 Models of Species Coexistence Assuming Equilibrium
Conditions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 47 Models of Coexistence Assuming Nonequilibrium Conditions . . . . 48
Are Diverse Grasslands More Stable, and, If So, Which Components of Diversity Are More Important? . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 51
How Can We Conserve Species Rich Grasslands and Restore Diversity to Degraded Grasslands? . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 52
Restoration of Grassland Biodiversity. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 53 Conclusions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 55 Acknowledgments . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 55 References . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 56
Grasslands are a major vegetation type covering about 30% of the terrestrial globe (Henwood, 1998) and providing a critical resource for pastoral and arable agriculture. Despite their significance, there remain fundamental theoretical and practical questions to be answered concerning species diversity in grasslands. This chapter is concerned with seminatural grasslands, i.e., human-influenced grasslands which occur in a wide range of geographical locations and climates when the natural climax vegetation (e.g., forest) has been cut down and vegetation is grazed or cut for hay, thus preventing trees from re-establishing. This chapter addresses four themes:
• How does grassland diversity vary in space and time? • What determines the number of species that may coexist and makes
some grasslands richer than others? • Are diverse grasslands more stable, and, if so, which components
of diversity are most important? • How can we conserve species-rich grasslands and restore diversity
to degraded grasslands?
