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Grazing Effects on Butterflies in a Mediterranean Woodland Ecosystem in Northern Israel

Gad Ish-Am1*, Talia Oron2

The effects of cattle grazing on biodiversity in Mediterranean woodlands are yet unclear. To assess these effects on butterflies, we conducted surveys in the Mt. Meron nature reserve (northern Israel) in two habitats over two years. In each habitat we chose one site that was grazed by cattle and, as a control, a similar ungrazed site. Belt transects (5 m wide) divided to 100 m replications, alternately crossed woody and batha (open vegetation) patches. Those transects were surveyed on ridges in 2015 (five times, 11 replications, 538 butterflies, 25 species), and in valleys in 2016 (nine times, 12 replications, 3,944 butterflies, 38 species). Each habitat was analysed separately. In both habitats, species similarity index between sites was high. Richness was higher in the ridge's control and evenness was higher in the valley's grazed site. In both habitats total abundance in the control was twofold higher, and for the woody affiliated butterflies it was even threefold higher. For the batha polyphagous and oligophagous butterfly species, abundance was similar between the sites, and for a few of those, associated with grazing increaser plants, it was even higher in the grazed than in the control sites. However, the batha monophagous species were more abundant in the control. Monophagous and endangered species were found to be more sensitive to cattle grazing. We conclude that the current cattle grazing management in Mt. Meron reserve affects butterfly populations negatively. Therefore, we recommend more regulated grazing and earlyseason suspension precautions, along with designation of no-grazing areas in reserves.