Relationship Between Grassland Corridor Characteristics and Flying Insect Biomass in Forest Plantations in a Grassland Context

ABSTRACT The expansion of human land use has led to significant loss of natural habitats. In forest plantations established in grassland ecosystems, remnants of native habitats persist as linear structures, such as roadsides, firebreaks, and stream margins, commonly referred to as ‘corridors’. Insects are highly sensitive to environmental changes, and their body size can serve as an indicator of habitat quality. We hypothesised that corridors within forest plantations that exhibit greater native vegetation cover, resembling natural environments, provide sufficient resources for insect development, resulting in increased insect biomass. According to the environmental filtering model, habitat characteristics in human‐modified landscapes and biotic interactions act as filters, promoting the loss of certain species and convergence in functional traits. We posited that environmental filtering is the primary mechanism structuring flying insect assemblages in these corridors, and that its influence diminishes with increasing corridor width and native vegetation cover. To test this, we quantified insect biomass through body size and abundance and analyzed variation in body size among collected flying insects in forest plantation corridors and larger patches (representing the natural environment). Also, we measured vegetation cover and corridor width, and we evaluated their relationship with insect biomass and its components. Our results indicate that intensive land use impacts insect biomass primarily by influencing insect abundance: larger patches support greater insect biomass and abundance than forest corridors. Additionally, we observed that most corridors had less variation in insect body size than expected by chance, a pattern consistent with the environmental filtering hypothesis.