Fragilidades nas interações entre aves e plantas em áreas prioritárias para a conservação

Abstract

Seed dispersal is a fundamental process in the life cycle of plants. Flowering plants have developed different strategies to ensure the displacement of their diaspores. In tropical forests, dispersal is mainly accomplished through interactions with different groups of animals. Birds represent one of the most important of these groups. However, the Anthropocene is characterized by intense deforestation, defaunation, and particularly fragile ecological interactions. Significant effort has been devoted to trying to understand the aspects related to the loss of these interactions. Within this context, the general objective of this thesis was to investigate the factors that jeopardize the processes of seed dispersal by birds in two hotspots for biodiversity conservation. First, we analyzed the influence of environmental fragmentation by monitoring the interactions in two areas of Cerrado stricto sensu with different conservation states: a fragmented area and a continuous (conserved) area. We then evaluated how the morphological correspondence between the ingestion capacity (beak width) of dispersing birds and the size of ornithochoric diaspores (fruits and seeds with attributes attractive to birds) can influence dispersal processes in a fragment of Atlantic Forest. We interpret these results in light of the metrics used in the construction of interaction networks and through empirical observations of interactions. We found that, in Cerrado, environmental fragmentation had a negative influence on the diversity of the dispersing bird guild and plant communities, in addition to causing functional homogenization, favoring the predominance of interactions between generalist birds and plants with small diaspores (≤ 10 mm). Further, our results in forest fragments demonstrate that the relationship between diaspore size and bird beak width acts as a filter in the dispersal process. We observed that dispersive resilience is lower in interactions involving larger diaspores (≥ 15 mm). We also bring an interesting case study in which the morphological incompatibility between the width of the beak of Hemithraupis guira (Thraupidae) and the size of the seeds of Cupania oblongifolia (Sapindaceae) seems to act as a pressure (at the individual level) favoring the development of behavioral traits to optimize foraging. Finally, we bring an article of