Density and fertility of Byrsonima pachyphylla A. Juss. (Malpighiaceae) in small fragments of the Brazilian Cerrado

Abstract

Habitat fragmentation is one of the main threats to the biodiversity of the planet. This study was conducted in nine fragments of the Brazilian cerrado (savanna) sensu stricto. We assessed the effects that fragment size and distance between fragments has on the density and fertility of populations of Byrsonima pachyphylla A. Juss. (Malpighiaceae), known in Brazil as "murici". In each of the nine fragments, we evaluated seven individuals. We quantified the B. pachyphylla density within a 20-m radius around each individual. Fertility in each fragment was estimated by determining the ratio between the number of flowers and the number of fruits produced. We carried out linear regression analyses between mean B. pachyphylla density and fragment size, as well as between mean B. pachyphylla fertility and fragment size. The influence of spatial autocorrelation on the fertility of each studied plant was estimated by Moran's I to evaluate the effect of fragment distance on B. pachyphylla fertility. Population densities and the proportions of fertile plants were greater in the larger fragments, which were also more preserved. There was spatial autocorrelation only between plants in the same fragment. Neighboring fragments differed significantly in terms of fertility, which is probably related to the degree of preservation of each fragment. Habitat fragmentation has a marked effect on the fertility of plant species in the cerrado, and larger fragments are needed in order to maintain their populations and those of associated species.