Spatial heterogeneity of fire and flooding patterns can support higher diversity of floral functional traits in an indigenous‐managed landscape

Abstract

In tropical wetlands, in addition to flooding, fire also contributes to the structure of biodiversity across environmental gradients. In fire‐prone ecosystems, flower‐rich fire refuges can be maintained by a seasonal patch‐burning mosaic. Here, we evaluate how a set of floral traits that influence and are related to the pollination systems of tree and non‐tree species varies in response to spatial patterns of fire frequency in a landscape with floodable and flood‐free areas. We classified the sampled species according to flower size, color, shape, symmetry, floral resource, type of pollination units, flowering duration, and anthesis time and compared them between floodable and flood‐free areas with high, moderate, or low fire frequency. We analyzed the functional richness in response to landscape metrics related to spatial patterns of fire frequency. The composition of floral traits of non‐tree species was stable, while tree species differed among fire frequency classes, especially in floodable areas. Many floral traits of tree species are ecological indicators, especially in floodable areas with high fire frequency. In contrast, among non‐tree species, only floral tissues as resources for pollinator were related to flood‐free areas with moderate/high fire frequency. The floral functional richness of the tree species positively linked with the modified Simpson diversity index, and for both trees and non‐trees, it negatively associated with the homogenization of the fire frequency (e.g., connectance based on probability that two adjacent sites belong to the same fire frequency class was negatively related to the functional richness of floral traits). These results demonstrate that homogenization of fire frequency in the landscape decreases the functional richness. Patches with different combinations of fire frequency and flood regime can support a shared set of floral traits besides those specifically related to a particular regime. The spatial heterogeneity of fire and flood patterns in wetlands needs to be preserved to support a higher diversity of pollination systems mediated by functional complementarity between the flowers of the tree and non‐tree species.