Study On Models And Associated Techniques Of The Conversion Of Farmland To Forest In Jinsha River Watershed Northeast Of Yunnan Province

The northeast of the yunnan province is the region that natural condition is the mostcomplicated, the antinomy of person and land is the most nervous, the environmentdeteriorates is the most serious. Implementing conversion of farmland to forest engineering,recovering plant , improving increasingly worsen of ecosystem environment and adjustingthe village industrial structure is the necessary way to carry out the social economysustainable development. Taking the northeast of the Yunnan province as the main object,according to the land use adjust and land type division, the project of plant distribution wasput forward, the distribution mode of accommodating different land type was chosen andthe homologous technique was provided in this research. Main research contents andconclusions were as follows: (1) After adjusting, the total programming of land use was Farmland: Woodland:Grassland: Other=18:60:12:10. The index of reclaim and cultivate declined from 29.42%to 18.35%, the rate of the forest overlay rise to 50-55% from 16.38%. The dynamicequilibrium of the proper farmland quantity could guarantee the safe general situation ofthe food in the district. (2) Dividing 8 set of land types, 31 land types, and inducing three districts themedium and high mountain, medium mountain, and the river valley, including the difficultafforested area in the dry heat river valley, corresponding to land, thus which covers maintype of the northeast of Yunnan province . (3) Put forward space layout of the district.(4) The analysis of main type of natural plant shows that: Pinus yunnanensis occupiedthe main existence space, the wood number was symmetrically distributed on each pathrank, wood age, and the structure of wood was stability. Alnus nepalensis forest showed thecharacteristics that the distribution was tight and the canopy density was high. For thecanyon area of the high mountain in the Jinsha River, it was better to adopt the near natureinstauration mode and the artificial promoting measure. (5)The bamboo in the district of medium and high mountain was Chimonobambusaquadrangularis>Phyllostachys aurea>Phyllostachys heteroclada;Castanea mollissima>Prunus percica> Litsea pungens;The bamboo in the district of river valley was better ,other tree species wasfrom large to small,Toxicodendron vernicifluum>Kalopanax septemlobus>Toona sinensis。Thespecies in the district of dry and heat river valley show a higher adaptability, that highgrow was:Tephrosia candida>Cajanus cajan>Meln iaazedarach>Delonix regi>Pistaciaweinmannifolia,the diameter at butt end is from large to small: Acacia confusa>Tephrosiacandida>Pistacia weinmannifolia>Delonix regia>Cajanus cajan.(6) The comparative results of different ecological function of allocation model wasthat the amount of surface runoff and sediment in the region of river valley was from largeto small, Dodonaea viscose(B)>Flousiana(D)> Cratoxylon prunifolium(A)>Kalopanaxseptemlobus(E)>bamboo(C);in the region of medium and high mountain: Pinus armandii(G)>Pinus yunnanensis(H)>Quercus acutissima(K)>Alnus nepalensis(J)>AcaciadealbataLinn(F).Dissimilarity installs the mode living creature quantity more.(7) The comparative results of biomass of different allocation model was that thebiomass in the region of river valley was from large to small,bamboo(C)>Kalopanaxseptemlobus(E)> Flousiana(D)>Cratoxylon prunifolium(A)>Dodonaea viscose(B);The total biomass of different allocation model in the region of medium and high mountainwas decided by the biomass of arbor's layer, The total biomass was positively anddistinctly related to the biomass of arbor's layer . The total biomass was from large tosmall, Acaciadealbata Linn(F)> Alnus nepalensi(sJ)>Quercus acutissima(K)>Pinus yunnanensis(H)>Pinus armandii(G).(8)The comparative of total productivity of different allocation model was that the inthe region of river valley was from large to small,bamboo(C)> Kalopanax septemlobus(E)> Flousiana(D)> Cratoxylon prunifolium(A)> Dodonaea viscose(B).The total productivity was positively and distinctly related to the litter's layer;In theregion of medium and high mountain, the total productivity was Acaciadealbata Linn(F)>Alnus nepalensis(J)>Quercus acutissima(K)> Pinus yunnanensis(H)> Pinus armandii(G).With the aggrandizement of canopy density, the arbor's layer strengthen obviously therepressive function of the shrub and the herbaceous plant.