Como a diversidade beta e a heterogeneidade dos usos do solo afetam a polínização do sub-bosque florestal?

Abstract

Ecological processes occur and interact in the landscape, which is why the study of landscape relationships with key ecosystem processes such as pollination can contribute to the development of more sustainable land use strategies. We studied the effect of landscape characteristics on the pollination of forest understory species, considering the relationships with beta diversity in the composition of plants and floral visiting bees and analysis of how the heterogeneity of land uses in the landscape can contribute to pollination. In areas of Atlantic Forest, State of São Paulo, we selected 28 landscapes of 1km radius in a gradient of forest cover. In each fragment we built hexagonal plots where we collected open flowers for analysis of pollination and floral visitors. In 20 landscapes, floral visitors were also sampled in adjacent open areas, in transects of up to 100m. We generated the following data: Landscape Shannon Index, proportion of use classes, composition of bee and plant assemblages in the understory and adjacent unmanaged open area, and measures of pollination of understory plants. In the first chapter we analyze the total beta diversity between different environments in the landscape, if it occurs predominantly by turnover or nesting, we relate it to pollination rates and finally we investigate whether the proportion of forest influences this diversity. We found that all environments have different species composition, mainly due to the high turnover rate, but that the difference in nestedness favors pollination in the understory and that the percentage of forest does not influence this diversity. We discuss that the high turnover may be due to increased isolation because of fragmentation and because the Atlantic Forest is a biodiversity hotspot with a high incidence of endemism and rarity among species, making this pattern of high turnover a trend in view of this high heterogeneity, natural in this environment. We also saw that pollination is favored by the sharing of species between forest areas and unmanaged open areas, making these regions complementary habitats. In the second chapter, we investigate whether the benefit of heterogeneity of land uses is due to a complementary effect of different types of environments, or to increase the probability of occurrence of favorable uses. We found that the proportion of unmanaged open areas, in interaction with the proportion of forest areas, contributed more to understory pollination than the heterogeneity of non-forest uses. This result reinforces that some anthropic uses are more favorable than others in maintaining pollinators and pollination. We conclude that priority should be given to the conservation of the greatest possible number of areas of natural vegetation, as well as the promotion of anthropic uses that provide resources for the species associated with them, and that the greater heterogeneity of uses is positive because it increases the chance of occurrence of favorable uses.