Grazing and mowing practices drive complex dynamics in the structure of butterfly communities in semi-natural grasslands
Data files
Mar 24, 2025 version files 330.17 KB
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Dryad_data.xlsx
327.49 KB
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README.md
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Abstract
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.
https://doi.org/10.5061/dryad.8kprr4xz3
Description of the data and file structure
Files and variables
File: Dryad_data.xlsx
Description: Data of the variables used to generate the Generalized linear mixed models.
Variables
- Itin / Secc: Identifiers for the itinerary and section where the data was collected.
- Year: Year of data collection (1993-2022).
- MEAN_SAVI / SD_SAVI: Mean and standard deviation of the Soil-Adjusted Vegetation Index (SAVI), an indicator of vegetation cover.
- Grazing_occurrence: Percentage of grazing detection between March and September.
- Mowing_occurrence: Mowing index, calculated by multiplying the number of mowing events detected in a year by the percentage of grassland cover. Not ever mowed sections had NA, and not mowed sections in a specific year had 0.
- Aperture_index: A metric indicating the openness or closeness of the habitat in relation to plant cover
- CSI (Community Specialization Index): Index measuring the habitat spezilization of the community.
- TAOC: Index measuring communtiy preference for open or closed habitat.
- Butterfly_abundance / Butterfly_Richness: Abundance and richness of butterflies in the study area.
- Yearly_Mowing : Annual mowing frequency. Not ever mowed sections had NA, and not mowed sections in a specific year had 0.
- Open_vegetation_cover: Open vegetation cover percentage.
- Rainfall: Annual precipitation (in millimeters).
- Temperature: Annual average temperature (°C).
- Aridity: Aridity index, derived from the relationship between temperature and precipitation.
- CODE: Site identifier code.
Code/software
We used Generalized Linear Mixed Models (GLMMs) to analyze how grazing and mowing occurrences influence the long-term spatio-temporal dynamics of butterfly communities. The analyses were conducted in R using the lme4 package, which allows for the fitting of mixed-effects models to account for both fixed and random effects in the data.
Access information
Data was derived from the following sources:
- CBMS: https://www.catalanbms.org/ca/
- Corine Land Cover: https://land.copernicus.eu/en/products/corine-land-cover
- Digital Climatic Atlas of Catalonia: https://opengis.grumets.cat/wms/iberia/espanol/es_presentacio.htm
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.