香格里拉大峡谷土壤特性及其人为活动影响研究

分析了长江上游香格里拉大峡谷的土壤特性及人为活动对生态环境造成的影响,结果表明:大峡谷土壤垂直分异明显,从海拔2000 ~ 5545 m分布有9种土壤类型。土壤C/N比值较大,反映了以有机质积累为主的土壤发育过程。自然土壤有机质平均含量100 g/kg,垦为坡耕地降至28.7 g/kg,撂荒地降至22.3 g/kg,旅游活动、过牧超载等人为干扰同样引起生态退化,自然干扰如火灾也引起土壤养分下降。另外,气候寒冷造成土壤利用性能受限,植被生长缓慢且破坏后难于恢复,对长江下游及附近地区自然环境的形成与演变产生重大影响。

SOIL CHARACTERISTICS IN SHANGRI-LA CANYON AND IMPACT OF HUMAN ACTIVITIES

The soils characteristics and impacts of human disturbances on the ecosystem of the Shangri-La Canyon were studied. The results show that 9 soils are distributed in clearly vertical zonation from 2,000m to 5,545m in altitude. The ratio of C/N in the soils is high, indicating that in the Shangri-la Canyon the soil formation processes were dominated with accumulation of organic matter. The average content of organic matter in the natural soil under forests is 100 g/kg, but is reduced to 28.7 g/kg after the soil has been cultivated as sloping cropland and to 22,3 g/kg in deserted farmland, which is evidence of soil degradation under the impact of human activities. On mire soil, harmful and poisonous weeds, such as Euphorbia jolkinii and Artemisia hedinii representative of soil degradation, are intruding into the meadow as a result of over-grazing. Soil degradation also occurs under the impact of nature disturbance such as forest fire. Moreover, the soil in the Shangri-la Canyon is higher than the soils in the other mountains areas in Yunnan, but cold weather limits the soil productivity and plant growth. Once the vegetation is destroyed, it is very hard to restore it. Thus the loss of forests with their function of conserving of water supply threatens the natural eco-environment in the vicinity and the down-streams of the Yangtze River catchment.