Sucesso reprodutivo de Styrax ferrugineus Ness et Mart (Styracaceae) em fragmento de cerrado sensu stricto no Campus da Universidade Estadual de Goiás, Anápolis, Brasil

Abstract

In the Brazilian cerrado species Styrax ferrugineus Nees et Mart. (Styracaceae) occurs predominantly in the west and midwest. Styrax ferrugineus presents a system allogamy associated with a self-incompatibility system. What makes this species highly sensitive to changes in internal and external variables such as inbreeding, pollen viability, fragmentation, number of pollinators, floral herbivory, plant density, population isolation and environmental quality, thus affecting the reproductive success of the species in the fragment of the population State University of Goiás-UnUCET. Thus the aim of this study was to evaluate external factors that are influencing reproductive success and maintenance of ecological interactions (pollination and floral herbivory) of Styrax ferrugineus Nees & Mart. (Styracaceae) in cerrado on the campus of the State University of Goiás, in Annapolis. The twenty individuals were marked in the field between May 2011 and August 2012 and followed the phenological events (flowers and fruit) phenological these intensities in the respective years were studied from data collected with the method proposed by Fournier. Six inflorescences per individual (n = 20) were marked and measured the buds, flowers and fruits in each focal individual was evaluated so the reproductive success of the species. To determine the influence of pollinators and herbivores on reproductive success were performed reason button / flower and fruit / flower inflorescences of two on two individuals, a bagged (to isolate the pollinators and herbivores) and other desensacada (free access to both). The influence of density and spatial isolation on fruit production of S. ferrugineus was analyzed using linear regression (Pearson correlation) and ANOVA, performed the reproductive efficiency (RE = natural pollination / pollination) to meet fruit production under conditions of maximum pollination. . Phenology of S. ferrugineus still begin at the end of the rainy season and early dry season, with a peak of flowers and fruits in May to July 2011 or 20,112 such events occur sequentially. Pollen viability was 94%. Reproductive success 61.65% of the buttons become flowers, and only 30.5% of the flowers produced fruits. Both in normal conditions (presence of pollinators) and the test inflorescences (bagged) the success rate was 33.93% and 5.7%, respectively. The density influenced significantly (r (Pearson) = 0.7451, t (calculated) = 4.7391, p = 0.0002) the reproductive success of the species. The population isolation increases the rate of formation of fruit significantly (α <0.001) when the species effected manual cross-pollination. We conclude therefore that there are factors that hinder the reproductive success of the species, human disturbance of local, high incidence of arson, isolated population at distances greater than the radius of foraging pollinators (Bombus sp.), the intrinsic characteristic of reproduction of the species and the main factor is the lack of pollinators in the study area.