Reproductive phenology of sympatric taxa of Chamaecrista (Leguminosae) in Serra do Cipó, Brazil

Abstract

Reproductive phenology of 13 sympatric taxa of Chamaecrista in three sections was surveyed at Serra do Cipó, south-east Brazil. Mean abundance of flowers and fruits per plant and mean number of aborted, predated, and surviving seeds per fruit were estimated. Monthly average number of developed seeds per fruit multiplied by the monthly mean number of fruits per plant gave the monthly average number of seeds produced by a plant of each taxon. Five types of phenological behaviour were differentiated by cluster analyses according to the season during which each species produced most of its mature seeds. This behaviour was related to the taxonomic section to which the taxa belong, to plant architecture, to geographical range, to seed predation and to local climatic seasonality. Herbs were more affected by variation in rainfall than shrubs and trees. Two species did not show any clear seasonal behaviour. Widespread taxa produced most of their mature seeds in the rainy season or immediately after it, and all but one of the narrowly distributed species produced most of their mature seeds in the dry season or in the transition from dry to rainy season. Seed predation is probably not an important selective force affecting reproductive phenology of larger taxa, while the smaller taxa seemed too constrained by abiotic factors for biotic factors to influence their phenology significantly.