The Process And Mechanism Of Soil Chemical Property Degradation In The Typical Mountain Region Of Western Yunnan

The studying area lying between 25o55ˊ ~26o0ˊ N ,99o48ˊ ~99o52ˊ E, in the mountain region of western Yunnan . As human demand for resources increasing and under the driving of economic benefits, lots of forests were destroyed. The forest was destroyed result in forest resource decreased, or degraded to low quality secondary forest or naked mountain. The natural ecological environment is destroyed seriously in study area, as well as the upper reaches of Lancang River and other mountain region of Yunnan. This has constituted threat to human survival and agricultural production. At present, there is short of study on soil degradation, especially the process and mechanism of soil degradation in the mountain region of western Yunnan. So carry out the research under the severe mountain conditions has important theoretical and realistic value.Affected by human disturbance, the natural broadleaf forest of western Yunnan has been destroyed, which causes soil degradation to change from natural broadleaf forest into needle broadleaved mixed forest, coniferous forest, slope and cultivated land and eucalypt forest. Given the noninterference of broadleaf forest could be experimental control; we have selected needle broadleaved mixed forest, coniferous forest, slope and cultivated land and eucalypt forest as the experiment sites to study the impacts of human disturbances on the soil chemical property in mountain region of western Yunnan. A two-year longterm study was carried out by applying IN-SITU technique to analyze the temporal-spatial changes of soil chemical properties. Reveal the soil degradation process and mechanism. Meanwhile provide the theoretical foundation for the similar region to restore the degraded soil ecosystem.The two-year study on the soil nutrients shows: As human activities aggravated, the content of soil nutrient declined. On the horizontal space, after the natural broadleaf forest was destroyed, the top layer (0-20cm) soil organic matter is decreased from the broadleaf forest to needle broadleaved mixed forest, coniferous forest, cultivated land and eucalyptus forest, the descending scale is 69.61%, 73.51%, 67.00%, 90.00%, respectively. The TN has the same trend with OGM. The top layer (0-20cm) TN is decreased from the broadleaf forest to needle broadleaved mixed forest, coniferous forest, cultivated land and eucalyptus forest, the descending degree is 70.22%,74.05%,50.54%,85.48%, respectively. The available nutrients spatially decomposed from natural broad leaf forest to needle broadleaved mixed forest, coniferous forest, slope and cultivated land and eucalypt forest. The descending range of hydrolysable N is 70.14～90.27%,of available P is 3.79～...