Study On Stability And Ecosystem Management Of Plantations In Dry-hot Valley In Yuanmou

Based on analysis of main climatic factors in Yuanmou dry-hot valley,soil physical and chemical properties,growth conditions,natural regenernation,species diversity among plantations.Then evaluate stability of the plantations synthetically and quantificationally,get the most stability plantation model.The research results are summaried as follows:From lately 50 years of climatic datum in Yuanmou,the changes of climate trend to relax,and develop in the direction of wetness.The are different from the soil physical and chemical properties among plantations.Through vegetation restoration,the soil nutrient contents of the plantationsgenerally better than check plots except the plot 25,the oil physical and chemical properties are better than the check plots.On analysis of growth conditions of every plantation,the best is the plot 25,that is Acacia.torulosa plantation,but appeared top-withering. Study on the natural regenernation of Acacia glauca and Leucaena leucacephala pure forest or mixed woodland,The number of ripe seeds of Acacia glauca isolated tree are lower than Leucaena leucacephala isolated tree,the percent is 47% of Leucaena leucacephala,but the dispersal distance is 110 meter ,and is 20 meter longer than Leucaena leucacephala.The annual seedings of the two trees do harm to serious drought stress,so the livability is very low. Seedings or saplings with 3 years or more can be seem in many Acacia glauca forest stands,not in Leucaena leucacephala pure forests bnt in the natural Leucaena leucacephala forest which formed by natural seeding and regenernation.The plot 5 is the best on effection of natural regenernation,which is Eucalyptus camaldulensis ×Acacia glauca mixed forest. The layer is singleness and species is few among plantations.The species are main-ly belong to Gramineae,Compositae,Papilionaceae. The number of species undergrow-th among different stands is fewer than wild lands. Heteropogon contortus,Eleocharis yokoscensis,Dodonaca viscose are very familiar.The plot 13, Eucalyptus camaldulensis pure forest ,is comparatively better than other plantations on biodiversity.Evaluated the plantations with ash association coefficient analysis,the result that the plot 5, Eucalyptus camaldulensis ×Acacia glauca mixed forest,is the most stability forest stands. The relatively stability plantations are the plot 7, Leucaena leucacephala pure forest;the plot 1, Eucalyptus camaldulensis ×Leucaena leucacephala mixed forest;the plot 9, Leucaena leucacephala pure forest;the plot 10, Acacia glauca pure forest.The relatively middle stability plantations are the plot 6, Acacia glauca pure forest;the plot 2, Eucalyptus camaldulensis ×Acacia glauca mixed forest;the plot 16, Eucalyptus citriodon×Leucaena leucacephala mixed forest;the plot 25, Acacia torulosapure forest.The instability plantations are the plot 13, Eucalyptus camaldulensis pure forest;the plot 19, Acacia mangium pure forest;the plot 21, Acacia aulacocarpa pure forest;the plot 23, Acacia confusa pure forest;the plot 17, Azadirachta indica pure forest;the plot 24, Acacia holosericea pure forest;the plot 12, Eucalyptus citriodon pure forest;the plot 11, Eucalyptus camaldulensis pure forest;the plot 14, Acacia auriormis pure forest.Aim at the plantations in Yuanmou,take measures by water and site management,optimize community structure,man-promoted natural regeneration,humanity factor.