Environmental controls on butterfly occurrence and species richness in Israel: The importance of temperature over rainfall

Aim Butterflies are considered important indicators representing the state of biodiversity and key ecosystem functions, but their use as bioindicators requires better understanding of how their observed response link to environmental factors. Moreover, better understanding how butterfly faunas vary with climate and land cover may be useful to estimate the potential impacts of various drivers, including climate change, botanical succession, grazing, and afforestation. It is particularly important to establish which species of butterflies are sensitive to each environmental driver. Location Israel, including the West Bank and Golan Heights. Methods To develop a robust and systematic approach for identifying how butterfly faunas vary with the environment, we analysed the occurrence of 73 species and the abundance of 24 species from Israeli Butterfly Monitoring Scheme (BMS-IL) data. We used Regional Generalised Additive Models to quantify butterfly abundance, and generalised linear latent variable models and generalised linear models to quantify the impact of temperature, rainfall, soil type, and habitat on individual species and on the species community. Results Species richness was higher along cooler transects, and also for hilly and mountainous transects in the Mediterranean region (rendzina and Terra Rossa soils) compared with the coastal plain (Hamra soil) and semi-arid northern Jordan Vale (loessial serozem soil). Species occurrence was better explained by temperature (negative correlation) than precipitation, while for abundance the opposite pattern was found. Soil type and habitat were insignificant drivers of occurrence and abundance. Conclusions Butterfly faunas responded very strongly to temperature, even when accounting for other environmental factors. We expect that some butterfly species will disappear from marginal sites with global warming, and a large proportion will become rarer as the region becomes increasingly arid.

Methods
These are summary data from Pollard (1977) transects of the Israeli Butterfly Monitoring Scheme (BMS-IL). The species occurrence data are taken from transects surveyed for at least 5 years (taking only the first five years for transects surveyed for longer). The species abundance data are sums of actual and imputed (modeled) counts of 24 easy to identify species for 2019. Imputed counts were calculated using Regional Generalized Additive Models (Regional GAM; Schmucki et al., 2016) through the package rbms version 1.0.0 (Schmucki et al., 2019). For more details, see the full text (Comay et al, 2021).

References

Comay, O., Ben-Yehuda, O., Schwartz-Tzachor, R., Benyamini, D., Pe'er, I., Ktalav, I. and Pe'er G. 2021. Environmental controls on butterfly occurrence and species richness in Israel: The importance of temperature over rainfall. Ecology and Evolution.

Pollard, E. (1977). A method for assessing changes in the abundance of butterflies. Biological Conservation, 12, 115-134.

Schmucki, R., Pe’er, G., Roy, D. B., Stefanescu, C., Van Swaay, C. A. M., Oliver, T. H. … Julliard, R. (2016). Regionally informed abundance index for supporting integrative analyses across butterfly monitoring schemes. Journal of Applied Ecology, 53, 501-510. https://doi.org/10.1111/1365-2664.12561

Schmucki R., Harrower C.A., Dennis E.B. (2019) rbms: Computing generalised abundance indices for butterfly monitoring count data. R package version 1.0.0. https://github.com/RetoSchmucki/rbms