A hydroclimatic regionalization of central Mongolia as inferred from tree rings

In arid and semi-arid regions of the world, such as Mongolia, the future of water resources under a warming climate is of particular concern. The influence of increasing temperatures on precipitation is difficult to predict because precipitation trends in coming decades could have a high degree of spatial variability. In this study, we applied a rotated principal component analysis (RPCA) to a network of 20 tree-ring chronologies across central Mongolia from 1790 to 1994 to evaluate spatial hydroclimatic variability and to place recent variability in the context of the past several centuries. The RPCA results indicate that the network consists of four tree-growth anomaly regions, which were found to be relatively stable through time and space. Correlation analyses reveal spatial linkages between the tree-growth anomalies and instrumental data, where annual streamflow variability was strongly associated with tree-growth anomalies from their respective regions from 1959 to 1994 (r = 0.52–0.64, p < 0.05). This study highlights the extent of spatial variability in hydroclimate across central Mongolia and emphasizes the value of using tree-ring networks in locations with limited instrumental records.     

Privatization, Drought, and Fire Exclusion in the Tuul River Watershed, Mongolia

Global wildfire frequency and extent are expected to increase under projected climate change in the twenty-first century, yet little is known about how human activities might affect this trend. In central Mongolia, there has been a 2.5°C rise in spring and summer temperatures during the last 40 years and a decrease in moisture availability during the latter half of the twentieth century. Concurrently, Mongolia has experienced multiple shifts in socioeconomic systems during the twentieth century, most notably the establishment of a Soviet-backed communist economy in the 1920s and a rapid transition to privatization in the 1990s. Observed records of fire in the late twentieth century suggested that fire activity had increased, but no long-term data existed to place these trends in a historical context. Our objective was to identify spatial and temporal patterns in fire occurrence in the forest-steppe ecotone of the Tuul River watershed in the context of changing climatic and social conditions since 1875. We used fire-scarred trees to reconstruct past fire occurrence during the period 1875–2009. Our results indicate a significant association between human activity and fire occurrence independent of climatic variables. The greatest evidence for an anthropogenic fire regime exists following the transition to a free market economy during the early 1990s when land-use intensification near the capital city of Ulaanbaatar resulted in fire exclusion. We emphasize the importance of including socio-political variables in global models of wildfire potential, particularly where fuels limit fire activity.     

Effects of large-scale forest fire followed by illegal logging on the regeneration of boreal forests in Mongolia

Landscape and Ecological Engineering - We aimed to test the hypothesis that large-scale forest fire followed by illegal logging inhibits the regeneration of boreal forests in Mongolia. For this...