Effects of Climate Warming and Vegetation Cover on Permafrost of Mongolia

Long-term monitoring of permafrost in Mongolia showed that permafrost under the influence of climate warming is ubiquitously degrading at different rates. The average trends of the increases in active layer thickness and mean annual ground temperature are 5–20 cm and 0.1–0.3°C per decade, respectively. These trends of the last 15–20 years are higher than those of the previous 15–20 years. Furthermore, the degradation of permafrost in the Hovsgol mountainous region is more intense than in the Hentei and Hangai mountainous regions. Experimental results have shown that vegetation cover, especially moss cover, forest, and dense grass, are natural insulators that maintain lower soil temperature and higher soil moisture by lowering the evaporation rate. Hence, intense grazing may accelerate the degradation of permafrost. Since permafrost plays an important role in the maintenance of ecosystems in this region, the recent degradation of permafrost may lead to significant changes in ecosystems, especially in the soil thermal state and moisture content.