Influence of vegetation cover on the functional diversity of macroinvertebrates associated with leaf litter in a stream of the tropical dry forest

Abstract

Vegetation is a fundamental element for the maintenance of macroinvertebrates functional diversity and, therefore, essential to aquatic trophic net preservation, being particularly relevant in threatened ecosystems such as tropical dry forests. Our aim is to determine the relationship between vegetal cover conservation and macroinvertebrates functional diversity associated with litter, in a stream from a tropical dry forest. In La Avería stream (Huila, Colombia), we sampled sites with different vegetation cover, estimated their physicochemical variables, and calculated leaf litter inputs (vertical, side, and drift) for each station for a whole year. Subsequently, we recorded the macroinvertebrates associated with litter from common vegetal species using leaf traps. We performed a PERMANOVA, added to multiple linear regression models and a redundancy analysis to correlate our environmental variables with changes in functional diversity. We observed changes in the functional parameters related to sampling zones and time. On one hand, functional richness and distance, are associated with dry seasons when resource availability and environmental conditions are stabilized. On the other hand, the functional evenness value diminishes in areas with higher pH due to the loss of individuals. We found evidence of a relationship between physicochemical variables and functional diversity. pH and precipitation changes were directly associated with changes in litter supply and therefore define the dimensionality of the functional traits in the ecosystem. Our work emphasizes the idea that the macroinvertebrate diversity carries great potential as a tool for decision-making in the preservation and environmental management of aquatic and riparian systems.