Understanding the effects of patch‐burn grazing management on aboveground grassland invertebrate biodiversity

Résumé fourni par la source

Landscape heterogeneity is widely recognized as a driver of biodiversity, yet its consequences for above‐ground, foliage‐dwelling insect communities under active grassland management remain underexplored. Patch‐burn grazing (PBG), which rotates fire across patches within a grazed landscape, is designed to promote spatial and temporal heterogeneity by creating a shifting mosaic of successional stages. In contrast, annual burning and grazing (ABG) imposes uniform disturbance. We tested how these contrasting strategies shape aboveground invertebrate communities across three years (2021–2023) in tallgrass prairie at the Konza Prairie Biological Station in Manhattan, Kansas. Using vacuum sampling, we quantified family‐level richness, evenness, abundance and functional composition of above‐ground, foliage‐associated insects; this method targets smaller, vegetation‐dwelling taxa. Contrary to expectations, PBG did not consistently enhance local (alpha) or beta‐diversity. Insect richness was higher in ABG in one year, while evenness was greater in PBG in another. Total abundances and functional group distributions were broadly similar, with only limited treatment differences. However, PBG significantly altered invertebrate community composition in two of three years, suggesting that heterogeneity influenced community structuring, even when richness was unchanged. Family composition differed between ABG and PBG in two of three years, driven primarily by higher and more variable Cicadellidae in PBG, with additional contributions from Acrididae, Formicidae, Curculionidae and Caliscelidae. Herbivory rates did not differ between treatments. Our findings reveal that using PBG to manage spatial heterogeneity leads to complex responses in insect communities, but may lead to distinct community compositions across the landscape. This decoupling of richness from composition highlights the importance of considering multiple biodiversity metrics when evaluating ecological outcomes. By fostering compositional variability without inflating herbivore pressure, PBG has potential as a heterogeneity‐based strategy for managing grasslands.

Ce résumé expose les affirmations des auteurs. BNTIC ne l’interprète pas comme une validation indépendante des résultats.