Response of moths (Lepidoptera: Heterocera) to livestock grazing in Mongolian rangelands

Overgrazing has become an ecological problem in the wide steppes of Mongolia due to rapid livestock growth in the last two decades. Species diversity and productivity of biological communities, along with information on the presence and absence of certain species, can be indicators of environmental health to assess the state of pasture. Moths have been used as indicator species in various studies as they are abundant in many different habitats and sensitive to environmental changes. We used moths as indicators for pasture degradation in the Mongolian steppe for the first time. In this study, we investigated how overgrazing affected moth species diversity, identified indicator species for degraded pasture and collected baseline data to study distribution and migration of moths under future climate change. To accomplish these objectives, we compared moth diversity in plots with different grazing intensity in two locations in central Mongolia. Species diversity of moths was two times higher in lightly grazed plots than in medium-grazed and heavily grazed plots. Thus we conclude that pasture degradation affected moth diversity negatively. As a result of indicator species analysis we identified four indicator species for heavily grazed plots (Leucoma salicis, Autographa buraetica, Mythimna impura and Pelochrista arabescana) and seven indicator species for lightly grazed plots (Panchrysia dives, Gastropacha quercifolia, Selagia argyrella, Lymantria dispar, Mythimna conigera, Stigmatophora micans and Perconia strigillaria). The meadow moth Loxostege sticticalis was most abundant in all plots. In this study we collected a total of 115 species from Ikhtamir and Undurshireet as baseline data in order to study distribution and migration of moths under future climate change.