A set of ecological conditions which provides a species with the energy and habitat which enable it to reproduce and colonize. A niche is usually identified by the needs of the organism. See Chave et al. (2002) Am. Nat. 159 on niche differentiation and the maintenance of species diversity. Etienne and Olff (2004) Am. Nat. 163 develop a simple model uniting a neutral community model with niche-based theory.