Habitat management interventions for a specialist mid- successional grassland butterfly, the Lulworth Skipper
Data files
Nov 29, 2024 version files 34.28 KB
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plotdata_2018_2021.csv
21.10 KB
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plotdata_simpsons.csv
11.12 KB
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README.md
2.05 KB
Abstract
Evidence-based management is needed to reverse declines in insect abundance. The Lulworth Skipper Thymelicus acteon is a range-restricted and declining species associated with mid-successional grassland, presenting challenges because interventions are necessary to prevent long-term habitat deterioration but can result in short-term reductions in quality. In addition, site management should be compatible for the focal species and for wider plant and insect diversity. We conducted factorial experimental management trials to understand effects of cutting and rotovation on the height and structure of vegetation containing the larval host plant Tor-grass Brachypodium rupestre. We monitored vegetation height, B. rupestre cover and plant diversity, and T. acteon larval presence over four years. Rotovation and cutting differed in their effects on habitat structure and larval occupancy relative to controls. Vegetation height and host plant cover, the most important components of habitat quality for T. acteon, were faster to recover to suitable levels on cut plots. However, larval occupancy increased more quickly on rotovated plots, where plant species diversity was also higher. Results suggest that due to initial negative impacts of interventions on T. acteon occupancy, low frequency or intensity management, such as managing sections of a site every three years, is advisable.
https://doi.org/10.5061/dryad.mgqnk996v
The dataset contains two csv files;
- plotdata_2018_2021 contains the data used to look at effects on larval occupancy including the descriptive summary, Kruskal Wallis Tests and GLMMs on larval occupancy.
- plotdata_simpsons contains similar data to the above but with an extra column on plant diversity index (Simpsons).
The results are based on management trial plots in a factorial design, whereby effects of cut and rotovate on Lulworth Skipper occupancy were tested. Data includes habitat information on vegetation height and food plant frequency.
Description of the data and file structure
The column headings are as follows:
year = year of survey
sites = sites
plot = plot ID
replicate = replicate ID
treatment = plot treatment
cut = whether a plot was cut (1) or not cut (0)
rotovate = whether a plot was rotovated (1) or not rotovated (0)
spring.veg = mean spring vegetation height (cm)
spring.coef = coefficient of variation from spring vegetation measurement s
summer veg = mean summer vegetation height (cm)
summer.coef =coefficient of variation from summer vegetationmeasurements
bp.freq = percentage cover of Brachypodium (larval host plant)
prop.bp = proportion cover of Brachypodium rupestre
aug.veg.prev.year = mean summer vegetation height from previous year
time = time since intervention, number of growth seasons (1=2018, 2 = 2019, 3 = 2020, 4 = 2021)
larvae.status = whether the plot was occupied (1) or unoccupied (0) by larvae
aug.coef.prev.year_check - the coefficient of variation (indicator of vegetation structure) for the plots for the previous year
Plotdata_simpsons
This spreadsheet, contains the plant diversity files the rows are labelled above are the same, and the additional rows are as follows;
rowid - row number (unique identifier)
sim_ind - simpsons index of plant diversity