ABSTRACT
Savannas are major land ecosystems comprising a global extent that has been estimated to vary between 15 and 37 million (M) km2 (House and Hall 2001). This broad range of area reflects the difficulties in defining what exactly is a savanna vegetation, not only due to its wide variability in plant diversity and degree of tree coverage but also because savannic areas shift considerably in decadal time frames due to changes in regional rainfall and land use. In the context of this article, a savanna is defined as a biome in which different combinations of grass, shrub, and tree strata occur, either as a roughly homogeneous mix in the same area or as a dominantly grassy landscape where shrubs and trees are sparse, or concentrated on patches or drainageways. Savannas occur in large areas in Africa and the Americas, but also in Southeast Asia and Australia. The word “neotropical” is traditionally used to refer to the tropics of the “New World,” especially South America. Neotropical savannas differ considerably from their African counterparts, more notably by a relatively more humid climate, high plant, and animal biodiversity (Grace et al. 2006) but paucity of large terrestrial animals, and a sparser human occupation (House and Hall 2001; Romero-Ruiz et al. 2012).
