Geospatial assessment of grazing regime shifts and sociopolitical changes in a mongolian rangeland

Drastic changes have occurred in Mongolia's grazing land management over the last two decades, but their effects on rangelands are ambiguous. Temporal trends in Mongolia's rangeland condition have not been well documented relative to the effects of long-term management changes. This study examined changes in grazing land use and rangeland biomass associated with the transition from the socialist collective to the current management systems in the Tsahiriin tal area of northern Mongolia. Grazing lands in Tsahiriin tal that were formerly managed by the socialist collective are now used by numerous nomadic households with their privately owned herds, although the lands remain publicly owned. Grazing pressure has more than tripled and herd distribution has changed from a few spatially clustered large herds of sheep to numerous smaller herds of multiple species. Landsat imagederived normalized-difference vegetation index estimates suggest that rangeland biomass significantly decreased (P<0.001) from the collective to the postcollective periods. The observed decrease was significantly correlated with changes in the grazing management system and increased stocking density (P<0.001), even when potential climate-induced changes were considered. Furthermore, field- and Satellite Pour l'Observation de la Terre imagerybased rangeland assessments in 2007 and 2008 indicate that current rangeland biomass is low. Spatial pattern analyses show that the low biomass is uniform throughout the study site. The observed decrease in rangeland biomass might be further accelerated if current grazing land use continues with no formal rangeland management institution or organized, well-structured efforts by the local herding households.