Rangeland degradation on the Qinghai-Tibetan plateau: A review of the evidence of its magnitude and causes

摘要

Rangelands of the Qinghai-Tibetan plateau (QTP), although sparsely populated and contributing little to China's overall economy, play an important environmental role throughout Asia. They contain high biodiversity values and can also potentially provide China with a source of cultural and geographic variety in the future. Chinese government reports paint a gloomy picture, considering vast portions of the QTP degraded and blaming irrational overstocking of livestock as the principal culprit. Global climate change, population increases, and "rodent" damage are also invoked as causes of rangeland degradation. In contrast, some Western observers claim that traditional pastoral practices were sustainable, and identify either previous or more recent state policies as the cause of degradation. Chinese governments at national and provincial levels have initiated a number of sometimes-conflicting and confusing policies aimed, at least nominally, at restoring rangeland productivity. On the basis of a comprehensive literature review, I argue that the extent and magnitude of rangeland degradation on the QTP remains largely unknown because monitoring programs have been subjective and poorly documented. Further, I argue that causes of degradation remain uncertain, often because hypotheses have been articulated too vaguely to test. No phenomena that have been hypothesized as contributing to rangeland degradation on the QTP currently enjoy unequivocal support. Where over-stocking is clearly causing damage, we lack sufficient understanding of current socio-ecological systems to identify ultimate and proximate drivers of pasto-ralist behavior, and thus policy initiatives aimed at sustainability may well fail.