Interspecific difference of mound morphological characteristics of two zokor species in the eastern margin of the Qilianshan mountains

The eastern edge of the Qilian Mountains is the sympatric distribution area of Gansu zokor (Eospalax cansus) and plateau zokor (E. baileyi). The mounds formed by high-density populations significantly affect grassland vegetation and soil. In order to clarify the morphological characteristics-related differences between the two zokor mounds and their relationship with environmental factors, we investigated Gansu zokor and plateau zokor mound morphological characteristics during the two activity peaks (i.e., breeding and food-hoarding seasons) and analyzed the correlation between the soil and vegetation factor-related differences. Our results revealed significant morphology-related differences between the two zokor mounds during the different periods. During the two periods, the Gansu zokor mound height, radius, surface area, and volume were significantly higher than those of the plateau zokor mound (P < 0.01). The plateau zokor mound density and average mound number were significantly higher than those of Gansu zokor (P < 0.05 and 0.01, respectively). During the breeding season, plateau zokor mound formation morphological characteristics highly correlated with the vegetation coverage, the underground biomass of sedges, the aboveground biomass of forbs, and the total underground biomass, while those of Gansu zokor highly correlated with the underground biomass of forbs. During the storage period, plateau zokor mound formation morphological characteristics highly correlated with the grass height, sedge biomass, and total underground biomass, while those of Gansu zokor highly correlated with the soil bulk density and the aboveground biomass of legumes. In conclusion, beyond the biological characteristics, environmental factors also correlated with the different mound-building modes, and their building modes displayed seasonal differences.