Potential nursing effects of Parkia platycephala Benth. (Fabaceae) in a disturbed Brazilian Savanna area undergoing restoration

Abstract

We evaluated the influence of Parkia platycephala on plant assemblages under its crown and surrounding areas in a disturbed Brazilian Savanna, as well as the effects of aqueous extracts of its leaves on the germination and development of three species, under the hypothesis that P. platycephala might work as a nurse species. Eleven areas of direct (ADIs) and indirect (AIIs) influence of P. platycephala and 11 control areas (COs) were delineated. All tree and shrub species present in these areas, including seedlings, were sampled. Richness, composition and abundance of woody taxa were determined. Laboratory studies analyzed the effects of P. platycephala aqueous leaf extracts on the germination and initial development of Dipteryx alata, Enterolobium gummiferum and Magonia pubescens, which in the field exhibited different abundance levels under its crown. Regarding plant assemblages, no differences in terms of richness and abundance of woody taxa were detected among the areas. However, we recorded a gradient of species composition and abundance ranks from ADI to CO areas. The number of seedlings also differed, with higher values near P. platycephala. Soil characteristics were similar among areas, but shading, plant height and diameter differed. The aqueous leaf extract at 25% provided the best germination of M. pubescens. The extract at 75% favored the initial development of this species in terms of root length. These results indicate that the presence of P. platycephala affects the structure of neighboring plant assemblages, possibly working as a facilitator for some species in areas undergoing restoration.