Structure and spatial distribution of Orthoptera communities in the taiga-alas landscapes of the Lena-Amga interfluve (Central Yakutia) Part 2. Orthoptera communities on the Abalakh Terrace

The second part of the paper presents the results of studies that examines species diversity, structure, biotopic occurrence, and spatial distribution of orthopteran communities in grasslands of the Abalakh terrace located in the LenaAmga interfluve. A total of 18 species from three families were identified throughout the research. Biocenological studies have shown that, in terms of species richness and general diversity, the Orthopteran communities on alas of the Abalakh terrace in 2019 exhibited similarities to those of the Tyungyulyun terrace; however, they were distinct in terms of total abundance. Thus, in the middle belt of the alas meadows, the maximum total abundance reached 670 specimens/100 sweeping, while in the steppe belts up to 790 specimens/100 sweeping. The cluster analysis of the data collected from the northeastern part of the Lena-Amga interfluve in 2019 revealed two main classes of Orthopteran communities. The first class was characterized by the absolute dominance of Chorthippus albomarginatus , where the contribution of the species to the structure varied from 70 to 100%. The second class was subdivided into a subclass of xeromorphic habitat communities with the dominance of Omocestus haemorrhoidalis and Chorthippus albomarginatus, and a subclass of wet meadow communities that feature a specific complex of hygromesophilic species. Chorthippus albomarginatu s, recognized as the most pest grasshopper species in Central Yakutia, was recorded in all alas hydrothermal belts, from wet meadows to forest edges and steppe slopes; in the majority of communities, this species dominated or was a subdominant. The cryoarid climate of Central Yakutia and the widespread taiga-alas landscapes necessitate a tailored approach to managing pest grasshoppers. In our opinion, the RAAT method (Reduced Agent and Area Treatments) represents the most viable strategy as its implementation could substantially decrease financial costs and mitigate damage caused to ecosystems during chemical treatment of farmland.