Text%2F2009-06!22!03!00!34hdmpbg45mbmm31buvsyslm55_Characteristics of Desertification and Its Rehabilitation in China

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    Characteristics of desertification and its rehabilitationin China YongZha* & JayGao†‡ *School of Geographical Sciences, Nanjing Normal University, Nanjing210097, People’s Republic of China†Department of Geography, University of Auckland, Auckland Private Bag 92019, New Zealand  (  Received 20 March 1997, accepted 16 June 1997  ) The definition of desertification and its causes in the Chinese literature arereviewed and compared with those in international publications. BothChinese researchers and their western counterparts have difficulty in reachinga generally accepted definition for desertification and an agreement upon theexact role played by human activities and environmental settings indesertification initiation and development. Tremendous efforts in China havegone into rehabilitating desertified land into productive uses with greatcontribution to existing knowledge in reclaiming desertified land. The earlybiological-oriented measures based solely on economic return have recentlybeen replaced by a much more successful, multi-disciplinary approach of rehabilitation combined with preventive measures that follow sound eco-logical principles.©1997 Academic Press Limited Keywords: desertification; causes of desertification; severity assessment;rehabilitation of desertified land; land reclamation; China Introduction With a territory of 9·6 million km 2 , China is one of the most severely desertifiedcountries in the world. Desertification is threatening the lives of close to 400 millionpeople and has affected about 3·3 million km 2 of land (Chen et al ., 1996). It is thusvery important to study desertification and rehabilitate desertified land into productiveuses. Although sand transport and sand dune movements were studied in the 1960s(Zhu et al ., 1964; Wu, 1965), these efforts were highly limited in their scope andquantity. Spurred by the United Nations Conference on Desertification (UNCOD)held in Nairobi, Kenya in 1977, immense research on desertification and itsrehabilitation has been carried out with fruitful results. In this paper the characteristicsof desertification in China are identified through a review of published papers. Theliterature cited, with a few exceptions, comes chiefly from journals and books recentlypublished in Chinese. Wherever relevant, the issues under consideration are discussed ‡Corresponding author.  Journal of Arid Environments (1997) 37 : 419–4320140–1963/97/030419+14 $25.00/0/ae970290© 1997 Academic Press Limited  in a wider scientific context through citing articles published internationally in Englishbooks and journals.According to UNCOD (1978), desertification refers to the ‘diminution ordestruction of the biological potential of the land that can lead ultimately to desert-likeconditions.’ Increasingly, it has been agreed that the term ‘desertification’ should berestricted to dryland environments only (Thomas, 1993). Therefore, land degradationin humid regions is beyond the scope of this paper. The various definitions of desertification are first presented, followed by consideration of its spatial extent andthe magnitude of the desertification problem. The causes of desertification and itsdevelopment are discussed next. Efforts to monitor desertification and to rehabilitatedesertified land into productive uses are reviewed. Finally, the outcome of therehabilitating efforts are summarized. Definition of desertification Coined by the French botanist and ecologist Aubr´eville (1949) nearly half a centuryago, the term ‘desertification’ has undergone numerous modifications in its meaningsince then. More than one hundred definitions have appeared in the English literatureso far (Glantz & Orlovsky, 1983). For instance, Rapp (1974) defined it as ‘the spreadof desert-like conditions in arid or semi-arid areas due to man’s influence or to climaticchange.’ However, no single definition is generally accepted (Dregne, 1983). Muchconfusion in the literature has occurred as a result of its unscrupulous use (Thomas &Middleton, 1994) in three aspects: (a) indiscrimination between the process of desertification and its state; (b) non-consensus regarding the geographic regions towhich it applies; and (c) its exact causes. Recently, Rhodes (1991) and Thomas (1993)suggest that the concept of desertification be revised in light of renewed scientificadvances that have enhanced our understanding of the problem. Namely, naturalfluctuation in environment causing long-term detrimental impact must be distin-guished from land degradation caused by human actions.The concept of ‘desertification’ was not introduced into the Chinese literature untilafter the UNCOD in 1977 (Chen et al ., 1996). Prior to that, the term tudi shahua (landsandification) was in common use (Dong & Liu, 1993). It refers to the coarseningprocess of the land surface after fine sandy and nutrient particles are lost to aeolianerosion. Though close to desertification in meaning, it at most forms a stage in thedevelopment of desertification (Zhu et al ., 1989). Another related term is called  fengshahua (aeolian sandification). It refers to the process of forming desert-likelandforms by sand outside arid and semi-arid zones (Zhu, 1986). However, Li (1988)argued that this process should be called strictly land degradation.Profoundly affected by its constantly changing international meaning, desertificationhas been dissimilarly defined by Chinese researchers. Zhu & Liu (1981) referred to itas ‘the process of environmental degradation in non-sandy areas where the fragileecology is disturbed by excessive human activities’. It was defined by Yang (1987) asa series of climatic and geomorphologic processes in arid, semi-arid, and some semi-humid sandy areas under the influence of various conditions at diverse time scales.According to Chen (1991), desertification is the contemporary process of landdegradation that is caused mainly by sand in a fragile ecosystem and forms a desert-likelandform. It is ‘the process of environmental change that is characterized bysandblasting and forms a desert-like landform in formerly non-sandy areas’ (Dong et al ., 1988). Apparently, these definitions differ from one another widely in the processand time scale involved.Lack of agreement in defining desertification srcinates in part from its confusionwith desertization because of inappropriate translation. Referring to desert encroach-ment in arid and semi-arid areas of non-desert landforms due to improper human Y. ZHA & J. GAO420  activities, desertization was translated as shamohua (desertification), whereas desertifi-cation was translated as huangmohua (barrenification) in Chinese. Zhou & Pu (1996)argued that the international definition was by no means perfect and had to be alteredto suit desertification peculiarities in China. The term huangmohua should be used inits broadest sense to encompass desert creeping, land degradation in the forms of soilerosion, waterlogging and soil salinization to avoid confusion.Unlike the international ones, these Chinese definitions place a much greateremphasis on the material (sand) that is essential in desertification initiation than onclimatic, especially precipitation, variables that are incorporated in the definitionimplicitly. All sandy deserts and lands are located in northern China that has an aridor semi-arid climate (Fig. 1). The proposed adoption of  huangmohua will undoubtedlymake the concept of desertification in Chinese closer to its international meaning. Severity of desertification Historically, many parts of China are susceptible to desertification. All of them areconcentrated in the north-western, northern and north-eastern (‘Three North’)dryland (Fig. 2). Some of these historical events of desertification have beendocumented by various scholars. Zhu et al . (1986) cited notable instances of widespread desertification in the semi-arid steppe (A in Fig. 2) dating back to the HanDynasty (202 BC – AD 220). Dong et al . (1988) found that the Mu Us Sandy Land (Bin Fig. 2) has existed since the Quaternary, even though its size fluctuated over theyears. It has been subject to the southward encroachment of a sandy desert since the Figure 1. Distribution of sandy deserts (1–8) and lands (9–12) with respect to climatic zones inChina. Sandy deserts and sandy lands are differentiated because the latter is formed out of human activities (Source: modified from Fullen & Mitchell, 1994). DESERTIFICATION AND REHABILITATION, CHINA421  Tang Dynasty ( AD 618–906) (Guo et al ., 1989). As a remarkable example of desertification in Chinese history, the Ordos Plateau (Fig. 2) contains 120,000km 2 of land that were desertified during the prehistoric period (Guo et al ., 1989). At itssouthern fringe a belt of migratory sand about 60km wide formed along the Great Wallduring the last three centuries. The history of desertification in the Taklimakan Desert(1 in Fig. 1 and F in Fig. 2) can be dated back to 31,000 years ago (Wang & Dong,1994).At present China still faces a serious problem of desertification. Approximately 13%of the territory comprises of deserts and desertified land (Qu, 1980). It is estimatedthat 3·3 million km 2 have been affected by desertification, accounting for 34% of totalland area (Chen et al ., 1996). Desertified land in China totals 1·1 million km 2 by theaccount of Zhu & Cui (1996), but 2·2 million km 2 by the account of Zhou & Pu(1996). None of the authors provided accuracy for their estimates. The sheer scale of the desertification problem, combined with its complex causes, makes accurateestimates impossible (Fullen & Mitchell, 1994). The massively disparate figuresreported are attributed to three reasons: (a) definition of desertification. The landaffected by a specific type of degradation was included in one figure, but not inanother. Guo et al . (1989) reported a total of 1·3 million km 2 of desert and desertifiedland without specifying the quantity for desertified land alone; (b) types of desertifiedland. Some authors included desertified land in arid and semi-arid areas whereasothers also counted the land degraded by erosion in humid and semi-humid areas. Zhu Figure 2. Distribution of historical and contemporary desertification in China. Numbersrepresent sandy deserts/lands; for their names refer to Fig. 1 (Source: modified from Sheehy,1992). Y. ZHA & J. GAO422
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