Existe influência da borda sobre a polinização e o sucesso reprodutivo de espécies lenhosas da Caatinga?

Abstract

Although neotropical forests are among the richest on the planet, the loss of habitat fragmentation by these ecosystems grows continuously. One consequence of fragmentation is the formation of edges, which can lead to changes in composition, structure and / or function of ecosystems, including the plant-animal interactions, this process is called "edge effect". Studies of fragmentation and edge effect are being developed mainly in temperate forests and wetlands, and less frequently in arid regions such as the caatinga. This study aimed to evaluate the effect of the formation of edges in the bush on the pollination and reproductive success of woody plant species. To this were characterized and compared between border areas and core frequencies of pollination syndromes of all woody species found in bloom, as well as reproductive success, the frequency of pollination and pollinator behavior in a woody plant species, located on the edge and inside. Overall difference in the probability of occurrence of the various floral attributes (color, size, floral type, unit pollination) and the pollination syndromes, the edge areas consist of more generalist pollination systems was observed, with light colors and floral types little and specialized as the distance increases, these attributes tend to occur in smaller amount. In contrast, more specialized systems tend to increase their probability of occurrence as the distance from the edge increases, as well as many floral traits. To Ruellia asperula L., significant differences in natural fruit production between edge and interior (X2 = 25.137, df = 1, p <0.01), in the formation of fruit through cross-pollination and the number of pistils with grains pollen on the stigma (χ2 = 10.46, df = 1, p <0.01). Differences in weight, size, and width of fruit (p <0.005) was also observed, all these parameters being larger in the inside. Significant difference was observed both in the frequency of visits, number of visits flowers (p <0.01), which is more on the edge. No significant differences were observed in the rate of pollen limitation (p> 0.01). The edge effect is interfering in pollination systems through changes in the composition of some species, favoring people with systems more generalist pollination, which could be pollinated by many specific pollen vectors. This impacts negatively on the frequency of visits and reproductive success of species located on the edge of the fragment, reflecting the amount of pollen deposited on the stigma and the number and size of fruits.