THE IMPACT OF INCREASED GRAZING INTENSITY ON WATER QUALITY IN WESTERN AND CENTRAL MONGOLIA FROM THE MONGOLIAN EMPIRE TO TODAY

Since the end of Soviet authority in 1991, traditional nomadic herders in Mongolia have seen incentives to increase the number of livestock in their household. Previous sampling of modern lakes and paleolimnological study have shown increased nutrient loads and deteriorating water quality in lakes from western and central Mongolia concurrent with this increase and a related trend toward concentrated rather than distributed grazing. However, climate warming and drought have been prevalent over the same time span and may also be an influence. We are investigating the use of the coprophilous fungus Sporormiella in lake sediment cores as a more direct marker for grazing intensity to better understand modern eutrophication and the impact of intensive grazing during wet climate conditions at the time of the Mongol Empire.

Sporormiella is found in the feces of wild and domesticated herbivores; preserved spores have been used as a proxy in the fossil record but have only recently been applied in more modern paleolimnological studies. We present preliminary evidence linking increased spore concentration in recent sediments with increased nutrient loads and find higher spore densities near roads and towns with permanent and intense grazing.

Historical records from the Mongol Empire (13^th century AD) suggest significant settlements, analogous to smaller towns in Mongolia today. The livestock population in the capital city of Karakorum in the 13th century is not well known, but based on estimates of livestock needs per person and traditional ratios of various livestock, over 15 million animals were likely pastured in the territory at its peak, with high and somewhat sedentary grazing likely near the capital - surprisingly similar to post-communist Mongolia.

Our present work combines sediment and diatom-based proxies for eutrophication with Sporormiella as a proxy for grazing intensity in recent (1900 - today) and historical (13^th century) lake sediments to examine (1) to what extent modern eutrophication is a result of livestock grazing (2) whether we can use the Mongol Empire as evidence that concentrated grazing, independent of drought, negatively impacts lakes and (3) whether there is evidence of water quality deterioration and recovery after the fall of the Mongol Empire that may offer context for the current situation.