Plant traits interplay to balance pollen limitation in the Brazilian seasonal dry forest: A meta-analysis

Animal pollination is one of the most important ecosystem services that benefit both natural plant communities and plant crops. A failure in pollination service can result in pollen limitation of fruit and seed set. This scenario can be even worse in endangered ecosystems such as tropical dry forests. Pollen limitation is a way of measuring the reproductive performance of plants by comparing the output of natural pollination with that of supplemental hand cross-pollination. Studies have shown that pollen limitation can be moderated by plant traits, such as plant habit, mating system, pollinator dependence and floral specialisation. Herein, we carried out a meta-analysis to determine the magnitude of pollen limitation in 60 plant species from the Caatinga vegetation of the Brazilian seasonal dry forest. We found an overall mean pollen limitation of 0.41 and a prevalence of 35%. Trees, shrubs, and self-incompatible, pollinator dependent and generalist plants were pollen limited. We found a significant interaction between plant habit and floral specialisation. Specialist and generalist trees and generalist shrubs were pollen limited. Trees and shrubs are mostly threatened in the endangered Caatinga. Species that are not pollen limited, such as lianas and herbs, may also be indirectly threatened by deforestation and intensive farming.