西藏大骨节病区的地理环境特征

西藏90%以上的大骨节病县分布在高山温带环境中,病区最暖月平均气温在10~18℃之间,≥0℃日数在180~350天之间;病区集中分布在喜马拉雅山与冈底斯山和念青唐古拉山之间以及横断山北段山间地带的山区或高山谷地地区,病县山地、丘陵占78.4%,非病县山地、丘陵面积占66.7%;就海拔高度而言,病区主要分布在3600~4000m之间;病区涉及多种类型的耕作土壤,其中酸性棕壤和暗棕壤、灰褐土和石灰性褐土、褐土性土等淋溶、半淋溶土壤类型是大骨节病集中分布区;在高山土壤类型中病区趋于分布在典型亚高山草甸土和山地灌丛草原土地带,而亚高山草原土带相对较少。西藏大骨节病区地理环境特征既与内地大骨节病区有很强的相似性,又因其独特的地域分异格局而具特殊性。

Features of Geographical Environment of Kaschin-Beck Disease (KBD) Affected Region in Tibet

Kaschin-Beck Disease is regarded as an endemic, deformed osteoarthropathic disease with high deformity rate. China is the country with widest Kaschin-Beck Disease incidence and prevalence in the world. The areas of endemic Kaschin-Beck Disease are relatively stable and correlated with specific geographical environments. It is mainly distributed in a broad belt extending from northeast to southwest, approximately covering the transitional belt between tropical and subtropical humid zone in the southeastern China and arid and semiarid northwest China. It only hurts the poor rural farmer. Since the 1980s, though the effective countermeasures for preventing, with the inhabitant living level increasing, the disease has been effectively controlled. But it is still active in some western areas, especially in the Tibetan Plateau. The affected counties in Tibet have been increased from 13 to 34 since the 1970s. As the Tibetan Plateau is a most special geographical landscape, where the horizontal and altitudinal regional differentiation are everywhere and complicated, it is important to systematically study the relationship between the distribution of Kaschin-Beck Disease and the differentiation of geographical environment to macroscopically guide the disease prevention and control in the areas. In this paper, with the help of ARCGIS 8.0 and SPSS 10.0 software, using the geographic data of Tibet (climate, soil and land use, etc.) surveyed in last two decades, the geographic characteristics of Kaschin-Beck Disease in Tibet are analyzed. The results show that more than 90% of Kaschin-Beck Disease affected counties are located in plateau-temperate zone. The average temperature of the warmest month is 10℃-18℃ and the days above 0℃ is between 180 and 350. Most disease affected counties are concentrated in the valleys between the Himalayas and the Nyainentanglha mountains, and in the north part of the Hengduan Mountains. Of the areas of the disease affected counties 78.4% are mountains or hills, 11.7% higher than those of the non-disease counties. The plain areas in disease affected counties are only 19.3%, 11.3% less than those in non-disease counties. Most heights of the disease sites are between 3600m and 4000m. The cultivated soils in disease affected counties are mountain soils. In east part of Tibet, the acidified mountain brown soil, mountain dark brown soil, mountain cinnamon soil, mountain calcareous cinnamon soil and gray cinnamon soil are typical soils in Kaschin-Beck Disease affected countries. In middle Tibet, Kaschin-Beck Disease is more distributed in subalpine meadow soil areas and less in subalpine steppe soil areas. The spatial characters of Kaschin-Beck Disease in Tibet are related both to the horizontal and the vertical distribution of the geographic factors. It is concluded that distribution and prevalence of the disease is correlated with the special regional differentiation of the Tibetan Plateau, cultivated soil in Kaschin-Beck Disease affected areas is mostly developed in semiarid and sub-humid stream valleys and scrubs steppe soil. This is very similar to the geographic characters of the disease distribution in inland China, as the geographic zonality of the Tibetan Plateau is almost replay the zonality in inland of China. Experiences and measures of Kaschin-Beck Disease prevention and control in inland of China, especially the measure of environmental improvement, can provide well examples for Kaschin-Beck Disease control in Tibet.