Fire frequency shapes diversity in multi‐guild communities through direct and indirect pathways

Abstract

Human-induced changes in fire regimes worldwide are leading to changes in the diversity and composition of plant and insect communities through alterations in vegetation and habitat characteristics. As species interact in complex networks, environmental disturbances, such as an increase in fire frequency, can affect species directly and indirectly through cascading effects across trophic levels.This study examines the effects of fire frequency on multi-guild communities in the Chaco region in Argentina, aiming to disentangle the direct and indirect pathways of influence between five different species groups: plants, phytophagous insects, ants, predators, and parasitoids.We assess cross-taxon congruence by analysing α and β diversity indices and performing a structural equation model and Procrustes tests, respectively, trying to elucidate the pathways of influence between fire frequency and the different guilds.Multi-guild communities responded to environmental changes produced by fire frequency via direct and indirect effects. Fire has both negative and positive, but weak indirect effects on predator richness through a bottom-up cascading effect from plant richness across phytophagous insects and ants. However, when species relative abundances were considered, no effects have been observed on Shannon and Simpson diversity indices. A positive correlation between species composition of different guilds and fire frequency indicated congruence between connected guilds suggesting that changes in beta diversity propagate across all trophic chains.Given an increase in fire frequency, changes posed to vegetation translated in weak changes via species richness but through pronounced effects on species composition across different trophic levels. Our findings emphasise the importance of a multi-guild approach to understanding biodiversity responses to environmental changes, highlighting the complexity and intricate dynamics of ecological communities in fire-prone ecosystems.