Grazing and mowing practices drive complex dynamics in the structure of butterfly communities in semi-natural grasslands

Rural abandonment and agricultural intensification are major threats to the conservation of biodiversity in Europe. Butterflies are excellent bioindicators of environmental change and can be used to assess the impact of global change on agroforestry mosaics. We used long-term spatio-temporal butterfly data to explore how grazing and mowing practices affect butterfly communities in the Northwest Mediterranean Basin. Changes in butterfly richness, abundance and habitat indicators were recorded using standardized transect counts. We focused primarily on the impact of management practices but also considered their interaction with other drivers (climate and habitat configuration). The most intensive levels of grazing did not correspond to the lowest butterfly richness; rather, they were correlated with lower abundances but supported a greater number of open habitat specialists. More intense mowing was also associated with low abundances and communities dominated by common and open-habitat species. Habitat configuration variables were also influential: open areas favoured greater butterfly richness and abundance, as well as more grassland specialists; greener vegetation, as measured by satellite imagery, led to an increase in butterfly abundance and communities composed of more generalist and forest species. Our study demonstrates the significant impact of grassland management on butterfly communities and offers insights into adaptive rangeland practices. It also indicates that increased levels of mowing and grazing can alter the composition of butterfly communities without necessarily affecting their diversity. This suggests that a dynamic restructuring of butterfly communities may occur in response to the environmental and habitat changes induced by these practices.

Methods
This dataset contains annual environmental and ecological data collected from 1993 to 2021. It includes variables related to vegetation cover, such as the Soil-Adjusted Vegetation Index (SAVI), derived from Landsat satellite imagery, and open vegetation cover obtained from the Corine Land Cover database. Land management practices, including grazing and mowing occurrences, were sourced from the citizen science project of the Catalan Butterfly Monitoring Scheme (CBMS). Biodiversity is represented by butterfly abundance and species richness, also collected through the CBMS, serving as key indicators of ecological health. Additionally, climatic variables such as rainfall, temperature, and aridity index, sourced from the Digital Climatic Atlas of Catalonia, provide insights into the site's environmental conditions over time. The dataset also incorporates butterfly-based ecological indicators, including the Community Specialization Index (CSI) and the TAncat- Obert index (TAOC), reflecting habitat preferences for open or closed environments.