Changes in ground beetle communities (Coleoptera: Carabidae, Tenebrionidae) in mountain depressions of the Tuva and Altai over 60 years: trend or fluctuation?
V. G. MORDKOVICH1, R. Ju. DUDKO1, S. A. KHUDYAEV2, I. I. LYUBECHANSKII1
1Institute of Systematics and Ecology of Animals SB RAS, Novosibirsk, Russia
2Institute of Soil Science and Agrochemistry SB RAS, Novosibirsk, Russia
Keywords: ground beetles, community structure, geographic range, ecological preference, diversity, abundance, mean annual temperature, annual precipitation, steppes, Siberia
Abstract
We studied the communities of soil surface Coleoptera (Carabidae et Tenebrionidae) in the mountain hollows of Altai (Kurai and Chuya) and Tuva (Ulug-Khem and Ubsu-Nur; in the latter, the arid western sector and the more humid eastern sector were studied). Collections were made in the same habitats at intervals of about 60 years: in 1962-1963 and in 2018-2020. Climate changes over this period were analyzed. In general, the climate of the characterized steppe depressions retained the features of sharply continental, with negative mean annual temperatures, moisture deficit and high frequency of fluctuations of all parameters. In all regions an increase in average annual temperatures and in the last 10-20 years an increase in annual precipitation has been observed, most strongly in the Ulug-Khem hollow, creating preconditions for reduction of aridity of ecological conditions. Over 60 years, the number of beetles of the studied taxa has changed several times, sometimes by more than an order of magnitude. At the same time, the number of representatives of the more xerophilic Tenebrionidae family fell, while the number of the more mesophilic Carabidae increased. When comparing the proportion of tenebrionids in the population of different habitats in the 1960s with their proportion in 2018-2020, a sharp, several-fold decrease in their participation in the communities is observed in almost all cases. More beetle species with a more northern or broader (polyzonal and/or transpalaearctic) distribution are becoming more common in the Tuva basins. Such species are found in both humid and arid regions. These changes in species compositions and soil-dwelling beetle communities may reflect mitigating climatic conditions due to some increase in precipitation in the studied region. The mean values of the indices of species diversity and abundance do not differ in general for the “before” and “now” ecosystem states. There are also no reliable differences for total species richness and total abundance. But there are noticeable interannual differences for some diversity indices calculated for Altai ecosystems in 2018 and 2020. This may indicate that differences between the overall diversity indices of ground beetle communities in dry and wet years overlap the long-term trend caused by climate change, and populations of species with different life strategies in the communities respond quickly to these changes without losing the overall structural complexity of the animal population.
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