| Jinsha River drainage area is one part of Yangtze River drainage area, and it has an typical fragile ecological environment. Ecological function and water conservation function of the forest in this area declined sharply, which lead to serious water and soil erosion. Study on the technology of resuming and rebuilding of the declining forest ecosystem has an significant meaning to the eco-security and sustainable development of Yangtze River drainage area.The research takes Yongren County (NFPP County) as main sites of the experiment. The idea of'Close to Nature Forest'is introduced for the research from the perspective forest ecological system. The research gives an systematic analysis on disturbance factors of different degraded forest ecological system ,including the heterogeneity in regional spatio-temporal scale of degraded natural forest habitat and community variation, category principles of degraded natural forest, grading criteria and categorizing system for degrading level, restoration system and evaluation criteria for the closure and conservation of degraded natural forest; Based on the experiment to carry out research on adapting the structure of the secondary natural forest at degraded stage for exploration of proper approaches for a rapid restoration, rehabilitation technology for heavy degraded forest, technology for improvement of large area of mono plantation in the natural forest area, restoration models for different degraded ecological system and ecological functions of different models. Feasible models for restoration and rehabilitation with corresponding techniques are selected for different degraded forest. Main research results are as follows:(1)It can be divided into 3 zones then 10 sub-zones of the natural forest eco-system in Jinsha River drainage area based on the structure and functions of its landscape system, and 4 categories based on its position in natural succession: slight degraded, small degraded, mid-level degraded and heavy degraded.(2)There are 4 feasible models for closure and conservation have been developed (strictly hillside closing, closing and forest structure adjustment, closing and afforestation and closing and forest stand improvement) for the upper of Jinsha River. Integrated together with corresponding technology, it makes an whole technological system for the restoration of the forest and 5 models for restoration and cultivation: tree forest, tree shrub, tree shrub and herbage, shrubs and herbage.(3)In the model of strictly hillside closing, all of species diversity, biologic productivity, physical-chemical properties of soil, water conservation capacity of the forest got an remarkable improvement.(4)In the model of hillside closing and forest stand structure adjustment, Quality of forest stand improved. Community structure got diversification. Community species diversity increased. Ecological function strengthened.(5)In the model of hillside closing and forest stand improvement, it takes a relatively short time for Pinus plantation forest stand in community structure changing from mono into mixture forest. Species diversity increased remarkably and capacity for water and soil conservation strengthened.(6)Study on afforestation of Alnus nepalensis, Sabina recarva, Cupressus torulosa, Cryptomeria fortunei, Alnus ferdinandi-coburgii, Pinus yunnanensis, Alnus nepalensis×Pinus yunnanensis, Alnus nepalensis×Sabina recarva, Pinus yunnanensis×Acacia dealbata and Cupressus torulosa×Alnus nepalensis in the model of hillside closing and afforestation shows: this model made soil fertility and water holding capacity improved, site condition is getting better. Soil structure improved greatly, fertility and water holding capacity improved after 4 years of afforestation. In Dry and hot valley, the restored vegetation with Quercus acutissima,Quercus franchetii,Quercus aliena is very stable.(7)Two drafts of technical rules were proposed based on the research. One is for rapid restoration and forest structure adjustment in Jinsha River drainage area of Yunnan and the other is improvement technical rules for mono plantation to close natural forest. The first one aims at open forest land, low yield forest land, shrub land, mid age young forest land and degraded grassland, and it puts forward five methods: closing with tending type, closing with replanting type, closing with adjustment, closing with improvement and closing with conservation (protection); The second one aims at mono plantation distributed in subtropical humid and semi-humid area, and it puts forward four methods: closing with adjustment, closing with tree planting, selective cutting with improvement and tending with improvement. |
