Correspondence Comment on “Why Large-Scale Afforestation Efforts in China Have Failed to Solve the Desertification Problem” The article “Why Large-Scale Afforestation Efforts in China Have Failed to Solve the Desertification Problem” by Shixiong Cao (1), which appeared in a recent issue of Environmental Science & Technology, proposed that large-scale afforestation appears to be causing increasing land degradation in arid and semiarid areas of China. To avoid misleading readers who may be unfamiliar with the area or the concepts, I have written this comment to clarify a few points. The main areas of desertification in China are currently located in northwestern parts of the country, including the Inner Mongolia and Ningxia autonomous regions, Shaanxi, Qinghai, and Xinjian provinces, and other nearby areas (2). The climate of northwestern China appears to be unsuitable for afforestation owing to the low rainfall. Historically, the forested areas of China have been distributed to the east of the 500 mm precipitation isoline, which comprises China’s humid or semihumid regions (3). In contrast, northwestern China has a semiarid or arid climate, with only 50-500 mm of annual precipitation; as a result, the natural vegetation is grassland or desert (3, 4). Previous attempts to solve the desertification problem by means of afforestation have failed several times in northwestern China: At the beginning of the 1980s, large-scale afforestation carried out in northwestern China by the central government failed completely (5). Simultaneously, an FAO afforestation project implemented in Hai-Yuan county Qinghai Province and China’s government’s afforestation project implemented in Inner Mongolia autonomous regions, where the annual precipitation averages less than 400 mm also failed (2). There has been an endless debate about the “Three Norths Shelter Forest System” project. Yet despite valid points made by
10.1021/es801718q CCC: $40.75
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2008 American Chemical Society
researchers on both sides of the debate, the survival of trees planted under this project has been only 15% during last 25 years (6). Although it is likely that some afforestation in northwestern China has been successful in areas with access to more water than the regional average, there seems to be little evidence that trees are capable of surviving in areas with less than 500 mm of precipitation; there is no historical evidence that trees were ever capable of surviving under these conditions, and the three studies I have cited provide additional evidence that calls this aspect of China’s afforestation policy into question (2-6). My own investigations across China during the past 20+ years have shown that afforestation in humid or semihumid hilly areas of southern China has generally been successful, but as Dr. Cao notes, efforts to use afforestation to solve the desertification problem in northwestern China have mostly failed (2).
Literature Cited (1) Cao, S. Why large-scale afforestation efforts in China have failed to solve the desertification problem. Environ. Sci. Technol. 2008, 42, 1826–1831. (2) Liu, X., et al. Science of Farming System. China Agricultural University Press, Beijing, 2005 (in Chinese). (3) Liu, X. The Problem of Forestry Ecology China’s Agric. Resource Plan 2005, 26(2), 14-17 (in Chinese). (4) Liu, X. Discussing of the natural problem at arid and semiarid area in Northwest China. Arid Semiarid Agric. Res. 2000, 18 (1), 1–8 (In Chinese). (5) Afforestation and grass planting in northwest china should be obeyed the natural and economic rules J. China Agric. Res. Region. Plan. 2000, 21(2), 8-10 (In Chinese). (6) Su, Y. Review of 25-year’s result of Three Northern Regions Shelter Forest System Project, China. Sci. Culture 2004, 3, 42– 44 (in Chinese).
Xunhao Liu College of Agronomy and Biotechnology at the China Agricultural University, and The State Research Council on Rural Development ES801718Q
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