Changes in Pastoral Land Use and their Effects on Rangeland Vegetation Indices

Extensive livestock production has been Mongolia’s major industry for centuries and traditional nomadic herding lifestyle and Mongolia’s expansive rangelands sustain this industry. After the democratic election and economic liberalization in 1992, formerly state-owned collectives were disbanded and Mongolia’s livestock population was privatized. There was no longer a state institution to formally regulate pasture use and herders became responsible for pasture use management. We studied the changes in pastoral land use management in Tsahiriin tal of northwestern Mongolia and their effects on rangeland Normalized Difference Vegetation Index (NDVI), a remote sensing satellite-based estimate of rangeland vegetation productivity. We estimated NDVI from the collective (pre-1992) and post-collective (1992-present) period using six different Landsat Thematic Mapper satellite images and compared the mean NDVI estimates from the two periods. Our results indicate that three major changes occurred in pastoral land use management. First, grazing distribution changed from localized clusters to a more evenly distributed pattern. Secondly, the grazing animal species changed from predominantly sheep to herds of sheep, goats, cattle, and horses. Third, grazing intensity increased by over 800 animal units. Our results also indicated that NDVI values from the post-collective period are significantly lower than the NDVI values from the collective era indicating that rangeland vegetation productivity might be declining in Tsahiriin tal. This decline in NDVI might be largely associated with the increased grazing intensity from the collective era to the post-collective period.