Restoration Prospects for Heitutan Degraded Grassland in the Sanjiangyuan

• Published in: Journal of mountain science 2013-08, Vol.10 (4), p.687-698
• Main Authors: Li, Xi-lai, Perry, George L. W., Brierley, Gary, Gao, Jay, Zhang, Jing, Yang, Yuan-wu
• Format: Article
• Language: English
• Subjects: Climate change; Earth and Environmental Science; Earth Sciences; Ecology; Environment; Environmental changes; Environmental conditions; Environmental degradation; Environmental restoration; Geography; Grasslands; Grazing; Ground cover; Land degradation; Meadows; Mountains; Soil erosion; Terrestrial ecosystems; Ungulates; 三江源; 有蹄类动物; 生物多样性; 稳定状态; 草原退化; 过度放牧; 退化草地; 青藏高原
• ISSN: 1672-6316; 1993-0321; 1008-2786
• DOI: 10.1007/s11629-013-2557-0

In many ecosystems ungulates have coexisted with grasslands over long periods of time. However, high densities of grazing animals may change the floristic and structural characteristics of vegetation, reduce biodiversity, and increase soil erosion, potentially triggering abrupt and rapid changes in ecosystem condition. Alternate stable state theory provides a framework for understanding this type of dynamic. In the Sanjiangyuan atop the Qinghai-Tibetan plateau （QTP）, grassland degradation has been accompanied by irruptions of native burrowing animals, which has accentuated the loss of ground cover. Severely degraded areas of alpine meadows are referred to as ＇Heitutan＇. Here, using the framework of alternate stable state theory, we describe the proximate and ultimate drivers of the formation of Heitutan on the QTP, and we assess prospects for recovery, in relation to the degree of biophysical alteration, of these alpine meadows. Effective rehabilitation measures must address the underlying causes of degradation rather than their symptoms. Heitutan degradation is not uni-causal. Rather it reflects different mechanisms operating at different spatio-temporal scales across this vast region. Underlying causes include overly aggressive exploitation of the grasslands （e.g. overgrazing）, amplification of grazing and erosion damage by small mammals when outbreaks occur, and/or climate change. Given marked variability in environmental conditions and stressors, restorative efforts must vary across the region. Restoration efforts are likely toyield greatest success if moderately and severely degraded areas are targeted as the first priority in management programmes, before these areas are transformed into extreme Heitutan.