Grasshopper Study in Eastern Shore of Lake Hovsgol, Mongolia
Yadamsuren Oyunchuluun and Clyde e. Goulden
This study aimed to investigate the distribution, species richness and abundance of Acridids (grasshoppers) in study valleys to determine whether they are affected by livestock impacts. As a result of taxonomic studies, about 217 Orthoptera species have been reported in Mongolia; of these, 42 species are recorded in the Hövsgöl region. In our study area 19 species are recorded, two of them new for the Hovsgol region.
The distribution of the grasshopper fauna was examined in 2002-2005 along a gradient of increasing grazing impact northward along the eastern shore of Lake Hövsgöl, Mongolia.
The responses of the grasshoppers (Acridoidea) to varying levels of livestock grazing and soil moisture were analyzed. There appears to be a negative correlation between grasshopper diversity and soil moisture (r2 = -0.5). The abundance of grasshoppers was significantly different among the study valleys and strata (p<0.001) with significantly more individuals in the heavily grazed areas than in the ungrazed and lightly grazed areas.
The abundance is highest in the upper and lower steppe on south facing slope, relatively lower in the lower steppe of north facing slope and lowest in the riparian zone.
Angarcris barabensis, Bryodema tuberculatum dilitum, Aeropus sibiricus sibiricus are abundant in grazed valleys and correlated with soil temperature and negatively associated with soil moisture. Aeropus sibiricus was the dominant species among the valleys. Mecostetus grossus was distributed in moist habitats but occurred less abundantly.
Various grasshopper species exhibited different responses to grazing intensity. Meso-xerophytous and xerophytous species were more abundant in the grazed valleys with low soil moisture and high soil temperature. Hydrophytous, mesophytous and xero-mesophytous species were more distributed in the low and ungrazed valleys.
These results related directly to the insect’s ecological features. Intense livestock grazing is leading to a drying trend in the valleys as a result of loss of soil moisture, an increase in soil temperature, and soil compaction (increasing of soil bulk density) and increasing grasshopper abundance in the heavily grazed areas.