Effects of anthropogenic disturbances on butterfly assemblages within undisturbed landscape matrix

The global decline of insects in general and pollinators in particular
poses a significant threat to biodiversity and ecosystem functioning.
Butterflies serve as sensitive indicators of environmental changes due to
their specific habitat requirements and rapid responses to ecosystem
alterations. Available studies are mostly devoted to analyzing the effect
of anthropogenic disturbance on abundance and diversity of butterflies
within disturbed landscape matrices. In this study, we investigated how
disturbances influenced butterfly populations within an undisturbed
landscape matrix usually overlooked in the literature. Eighteen sites were
monitored biweekly from May to September over three years (2022–2024)
using standardized visual counts along 500 m long transects. Grazing
intensity and the surface of human-disturbed lands were used as a measure
of disturbance at local and landscape scales. A total of 16,017
individuals and 78 species were recorded. No significant differences in
species richness or abundance were observed across the land use types, but
analyses showed distinct species compositions between cultivated sites and
grasslands. Butterfly community compositions were mainly influenced by
structural habitat characteristics rather than land use. Low grazing
intensity and the presence of forests in the surroundings positively
influenced abundance and species richness of butterflies. Within an
undisturbed landscape matrix, cultivations play a different ecological
role than in disturbed landscape matrix increasing landscape heterogeneity
and butterfly diversity and hosting ecotonal communities. Anyway,
disturbed land use types inhabit impoverished butterfly communities
compared to semi-natural ones in which the presence of protected species
further emphasizes their critical role for conservation.