Climate controls override grazing effects under extreme conditions of Central Asia

Mongolia and China host some of the most extensive and environmentally diverse rangelands, including the world’s largest alpine environments on the Tibetan plateau, some of the most extreme deserts in northern China and the vast steppes of central and eastern Mongolia. Animal husbandry is the main land use type across the region, with sheep and goat being the dominant species, supplemented by e.g. yaks in Tibet, horses in northern Mongolia or camels in the Gobi region. Estimates of grazing degradation in the region vary hugely, rendering development of urgently needed management strategies difficult. Part of this uncertainty is rooted in the lack of standards for degradation assessments such as selection of suitable indicators, and also in failure to calibrate assessments for the local abiotic context. Most notably, interactions between climate and human land use still are poorly understood.

The talk presents results from own research in Mongolia, northern China and Tibet, combining standard fencing experiments with large-scale transect studies and literature reviews. Although degrees of herders’ mobility vary across the region, land use can still be seen as relatively homogeneous. In contrast, climatic conditions differ strongly as shown by the altitudinal range covered (<1000 - >4000 m asl.) and the range in mean annual precipitation values (<100 mm – 700 mm MAP). Results from the dry and / or high-altitude ends of these gradients clearly show that climate exerts the dominant controls on vegetation, soils and insect indicators. At the extreme sites, grazing impact thus is relatively limited. Grazing effects are more pronounced in more mesic conditions, but even here they are not universally negative. Degradation threat may, however, be high in transition zones, near large settlements and under conditions of sedentary livelihoods with reduced mobility and limited flexibility in response to environmental extremes. Although these results are well in line with established theory, they have not yet been fully appreciated in current discussions on land use policies in both China and Mongolia.

*** Invited by Jürgen Dengler, Plant Ecology

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