Savannas and Grasslands
Niti B. Mishra, Kenneth R. Young
Abstract
This entry discusses the ecological features of the extensive and important ecosystems of savannas and grasslands, which provide habitat to important species, regulate an important part of the Earth’s nutrient cycles, and serve many purposes for people. The savannas are mostly tropical ecosystems wherein dominant woody and herbaceous plants coexist. In turn, grasslands are found in both tropical and temperate climates. Place-to-place changes in vegetation structure and land cover are caused by the interactions of plant available moisture, plant available nutrient, herbivore, and fire. Brief descriptions of these ecosystems are followed by a review of the significant ecological determinants of the structural and functional characteristics in savanna and grassland systems. There are a number of conceptual models that attempt to explain features of these ecosystems, including the unique coexistence of tree and grass life forms in savannas. Current threats to the sustainability of savanna and grassland systems worldwide arise as socio-economic processes interact with global environmental changes.