human impactsDespite its inaccessibility due to extreme topography and climate, the Mountains of Southwest China Hotspot is still heavily impacted by human activity. High population growth rates among the inhabitants of the region and immigration from other parts of China have exacerbated the pressures on natural habitat. Until a 1998 logging ban, one of the most serious threats to the area was intensive commercial logging. Forest cover in Sichuan Province, one of China’s main sources of timber, declined from 19 percent in the 1950s to 12.6 percent in 1988. Almost all this loss was in the more remote and mountainous western part of Sichuan, since forests elsewhere in the province were cut long ago. Today, even with the ban on commercial logging, forests are still being logged at a significant rate for firewood collection and house construction, particularly in the bitterly cold high valleys of the region. In some areas, the volume of extraction for these purposes may even exceed past logging harvests.With the exception of scree slopes and vertical cliffs, areas with no forest cover or that are unsuitable for crops are heavily impacted by large herds of grazing animals, such as yak, sheep, and goats. These animals are brought to the region by nomadic Tibetan herdsmen, who ascend to alpine pastures in the summer and return to the valleys before winter. In some cases, standing forests have been cleared to increase pasture for the growing domestic herds. Both logging and overgrazing have predictably led to serious erosion on steep slopes and to the siltation of rivers. Emerging threats include dam building on all main rivers in the hotspot, mining, and unplanned mass tourism development, all of which are accompanied by road expansion. For example, the Chinese government has proposed the construction of eight large dams on the upper reaches of the Lancanjiang, or Mekong River, in Yunnan Province. The dams will affect sediment transport and the river’s flooding cycle, and will drastically alter ecosystems both upstream and downstream of the sites. As mentioned above, this river flows through Yunnan Province, as well as Laos and Cambodia; the lives and livelihoods of millions of people living in these areas could be affected. Also, increasing access to disposable income and leisure time allows more and more Chinese citizens the opportunity to visit nature reserves and wilderness areas. Controlled tourism can provide an excellent alternative to logging and other harmful land uses; however, the construction of roads, hotels, and cable cars, along with the presence of large numbers of people in wild areas, can all lead to severe habitat degradation.It has been calculated that the remaining forest cover totals 23 percent of Yunnan Province, 12 percent of Sichuan Province, and 5.1 percent of The Tibetan Autonomous Region (TAR) in 1992. In all, only about eight percent of the original extent of the hotspot remains in pristine condition. Since the 1980s, and particularly from the late 1990s onwards, forest regeneration has been taking place on logged sites and “wasteland.” This has led to an increase in overall forest cover. However, most of this increase is accounted for by monoculture plantations, including stands of alien species such as the Japanese Pine.As in many of the hotspots in and around China, the collection of plants and animals for traditional medicinal purposes poses an enormous threat to the long-term viability of species in the Mountains of Southwest China. Among the species affected by this trade are monkeys, snakes, geckos, deer, and bears. Illegal hunting is also a major problem, and skins of protected species are frequently seen on the black market.
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© Diane Chang
Deforestation along river valleys, and logging in general, represent a major threat to biodiversity in the region.
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