Relação heterogeneidade da vegetação e diversidade de artrópodes pode ser modulada pela sazonalidade no Cerrado

Abstract

Understanding the drivers of arthropod diversity in seasonal ecosystems is fundamental to advancing our knowledge of the ecological processes that structure biological communities. Two of the main mechanisms that explain this dynamic are environmental heterogeneity and climatic seasonality, which act as ecological filters directly influencing species distribution, abundance, and richness. In this context, this study evaluated how structural attributes of woody vegetation: density, biomass, and species richness, combined with seasonal variation throughout the year, affect the diversity of terrestrial arthropods in a cerrado sensu stricto area. The study was conducted at the Reserva Ecológica do Panga, where a grid of 12 plots spaced 200 meters apart was established in a typical Cerrado area. Arthropod fauna was sampled bimonthly over one year using standardized sweep net sampling in the vegetation. Simultaneously, vegetation structure was characterized through a floristic survey in each plot, recording all woody individuals taller than one meter. These data were then used to estimate the density, aboveground biomass, and species richness of woody plants in each plot. The results indicate that, overall, the abundance and richness of terrestrial arthropods showed strong temporal variation, with sharp increases during the rainy season (October to April) and pronounced declines in the dry season (May to September). In contrast, the response to structural variations in vegetation was less consistent and limited to specific periods. Plots with higher density and species richness of woody plants tended to show lower arthropod abundance in certain months, particularly during seasonal transitions, suggesting that denser and more diverse vegetation may act as a physical barrier, restricting arthropod movement, foraging, and sensory communication. On the other hand, plant biomass had occasional positive effects on diversity, particularly during the rainy season when microclimatic conditions are more favorable, and the availability of resources such as shelter and microhabitats is higher. Despite these spatial effects, seasonal patterns proved to be predominant, with temporal variation playing a dominant role in regulating arthropod abundance and richness in the Cerrado. The substantial increase in diversity during the rainy season reflects a direct response to improved environmental conditions, while the dry season imposes severe constraints, resulting in significant reductions in community activity and diversity. Therefore, this study reinforces that, in highly seasonal ecosystems such as the Cerrado, temporal dynamics function as a stronger ecological filter than vegetation structural heterogeneity, highlighting the need to jointly integrate spatial and temporal dimensions to fully understand the processes that shape biodiversity in these environments