The joint effects of forest habitat area and fragmentation on Dung beetles
Data files
Aug 21, 2023 version files 55.31 KB
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MSR1.data.EcolEvol.July.2023.txt
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README.MSR1.data.EcolEvol.July.2023.txt
Aug 21, 2023 version files 55.46 KB
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MSR1.data.EcolEvol.July.2023.txt
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README.md
Abstract
Habitat loss and habitat fragmentation usually occur together, at the same time and place. However, while there is consensus that habitat loss is the preeminent threat to biodiversity, the effects of fragmentation are contentious. Some argue that habitat fragmentation is not bad for biodiversity, and even that it is good. Generally, the studies that find no harm or positive outcomes of fragmentation invariably assume that it is independent of habitat loss. However, dissociating the effects of habitat fragmentation from habitat loss is questionable because the two are essentially coupled. Accordingly, we evaluated how forest area and fragmentation (via edge effects) influenced dung beetles per se, and through their effects on the abundance of mammals, using structural equation modeling (SEM). Dung beetles are very sensitive to forest habitat loss and fragmentation, and to changes in the abundance of mammals on which they depend for dung. Our study area was in the Tana River, Kenya, where forest fragments are depauperated of mammals except for two endemic species of monkeys. We mapped 12 forests, counted the resident monkeys, and sampled 113,955 beetles from 288 plots. Most of the 87 species of beetles found were small tunnellers. After implementing a fully latent Structural Regression SEM, the optimal model explained a significant 26% of the variance in abundance, and 89% of diversity. The main drivers of beetle abundance were positive, direct, effects of forest area and number of monkeys, and negative edge effects. The main drivers of diversity were the direct effects of the beetle abundance, indirect effects of forest area and abundance of mammals, and indirect negative edge effects. Thus forest area, fragmentation (via edge effects), and the number of monkeys jointly influenced the abundance and diversity of the beetles directly and indirectly.
README: The joint effects of forest habitat area and fragmentation on Dung beetles
https://doi.org/10.5061/dryad.9cnp5hqkt
Columns A to AA contain the covariates associated with each plot (plotID)
Each row represents a plot, 5 pitfalls combined constituting one visit to one sampling station on one of the six sampling periods
All data are original measurements, i.e. not transformed for normality.
- abdist2matrix.m, Distance of the plot to the matrix in meters
- allIndividuals, sum of all individuals of all species in the five pitfalls from the same plot
- asy.Hill.q0, asymptotic species richness for this plot
- asy.Hill.q1, asymptotic Shannon diversity for this plot
- basA, basal area of trees in the plot in square centimeters
- cent2matrix, centrod distance to matrix in meters
- colo.mang.grp, colobus and mangabey groups in the forest where this plot was located
- colo.mang.inds, number of colobus and mangabeys in the forest where this plot was located"
- comb.area, area of forest fragment (m2)
- comb.area.perim, area-perimeter ratio
- comb.perim, perimeter of forest fragment (m)
- cutbasA, basal area of cut stems in the plot in square centimeters
- east.west, location of plot on the east or west bank of the Tana River
- forest, an identifier-name-for each forest fragment
- Hill.q0, species richness (reference sample)
- Hill.q1, exponential of Shannon diversity index (reference sample))
- larg.mg, mass of large sized beetles in this plot in milligrams
- mang.grp, number of mangabey groups in the forest where this plot was located
- mang.inds, number mangabeys in the forest where this plot was located
- med.mg, mass of medium beetles (milligrams)
- NA, stands for ""Not Available"" representing a missing value
- plotID, beetle sampling plot accounting for year and month sampled
- samp.month, an identifier for the month samples were taken
- transectID, an identifier for each transect in each forest fragment
- tunn.mg, mass of tunnelling beetles (milligrams)
- utm.x, eastings UTM coordinates of forest fragment
- utm.y, northings UTM coordinates for forest fragment
- year, an identifier for the year the samples were taken