摘要
本文根据类似荒漠境况的出现是判断荒漠化发生与否的重要标志这一原则，并结合在中国南方开展的一些研究，对湿润地区的荒漠化进行了初步的探讨。研究表明，湿润地区的荒漠化并不包含所有存在侵蚀作用的退化土地，而专指人为侵蚀作用导致的出现了具类似荒漠境况的退化土地。中国南方湿润地区土地荒漠化分布最显著的特征为斑点状分布于丘陵山区或河、湖、海滨的冲积平原，面积为1．98×105km2，其中流水作用导致的荒漠化面积为1．78×105km2，风力作用的为0．11×105km2，其它0．09×105km2。自然因素，特别是气候和地貌因素对荒漠化的形成和发展起着积极的影响作用，但不是决定作用。人为不合理的经济活动，才是造成荒漠化的主要原因。文章最后还简要介绍了湿润地区荒漠化的防治问题。
Desertification means land degradation in arid, semiarid and dry subhumid areas resulting from various factors, including climatic variations and human activities. The processes of land degradation include soil erosion caused by wind and / or water;deterioration of the physical, chemical and biological or economic properties of soil;and long-term loss of natural vegetation. The degraded land, which is manifested itself by desert-like conditions, is usually distributed far away from desert Scientifically,desert-like conditions can be observed not only in arid, semiarid, and dry subhumid areas, but also in humid areas. The situation of the process of environment changing toward to a desrt-like conditions in humid areas is more serious than that in arid,semiarid, and dry subhumid areas. This paper presents a preliminary approach to desertification in humid areas according to the research results obtained in the southern China. where the temperature varies from 14～20℃, and the precipitation is 900 mmin the north and 2 000 mm in the south. Considering desert-like conditions such as the broken surface, the dense gully and ravine, poor soil, drought and sparse vegetation are the symbol of desertification formation, and the term desertification in humid area can be used when land is degraded to such a point that desert-like conditions appear in the former degraded land caused by hUman activities. In other word, desertified land doesn't include all degraded land, where desert-like conditions do not occur in humid areas. The desertification in the humid areas of southern China is prominently distributed in patches in hilly and mountain regions covered by weathering crust of red clay,Quaternary red clay, granite and limestone, and in the flooding alluvial fans and fluvial sandy terrance along the coast lower reaches of some rivers and shores of lakes. Desertification in the weathering crust of red clay, which is manifested itself by rocky-slopland, is mainly distributed in the basin of Sichuan Province, the middle part of Hunan Province and the western Zhejiang Province. The area of such desertified land in the basin of Sichuan Province accounts for 3.7% of water-eroded land. The desertification in the weathering crust of Quaternary red clay, manifested itself by badland, is mainly distributed in Jiangxi Province, Hunan Province, Hubei Province,Zhejiang Province, Guangxi Province, Fujian Province etc. The desertification in Lanxi of Zhejiang has changed from 9.4% in 1970s to 10.5% in 1980s. The desertification in granite areas, manifested itself by strong erosion, is distributed in the Guangdong Province, Fujian Province, Hunan Province, the eastern Guangxi and the southern Jiangxi Province. The desenified land in Wuhua of Guangdong Province accounts for 62. 1% of total land area. The desertification of the limestone weathering crustmanifested itself by rock-desertification, is distributed in the Sichuan Province, Guizhou Province, Yunnan Province, Guangdong Province and Guangxi Province. In Guizhou Province, dertification has expanded from 5% of total area in 1970 s to 8% up to dare,and amount to 65% of total cultivated land. The annually expanding rate of rocky-desertification is about 57 km2 in Sichuan Province. The area of desertifed land in humid areas in southern China is estimated to be 198 000 km2, of which 178 000km2 of desertification manifested itself by badlands and rocky-covered slopeland is the result of water erosion, 11 000 km2 manifested itself by sandy surface and shifting sand dune is the result of wind erosion, and 9 000 km2 of other causes. The natural factors especially climatic and geomorphologic factors are recognized as the main factors for the formation of desenification while human factors such as destruction of vegetation, reclamation of steep slopeland and irrational industrial activities are the mainly contribution to the formation of dersertification in humid areas.The history of desertification development is closely related to human activities in racent one or two hundred years. The damage o
出处
《第四纪研究》
CAS
CSCD
北大核心
1998年第2期173-181,共9页
Quaternary Sciences
关键词
湿润地区
类似荒漠境况
人类活动
荒漠化
humid areas
desert-like conditions
human activities
desertification
