Study On Effect Of Different Transformation And Cultivation Models On Natural Secondary Quercus Mongolica Forest In Daxing'an Mountains

The forest in Daxing'an area has been seriously degraded by various natural and man-made factors.The forest has a large area,such as the decline of the forest,the low canopy density,the poor quality of the tree,the low yield of the forest,the serious soil erosion,the low soil fertility and the weak adjustment of the whole system.In recent years,more and more experts and scholars have contributed to improving the biodiversity of forests,increasing the yield and quality of wood forest products,improving the nutrient status of the soil,and improving the light conditions under the forest.The research site is located in Cui Feng forest of JGD Forestry Bureau.The research object was the natural secondary forest of Quercus mongolica.It was located at 12.5 kilometers from the Cui Feng to the Gu Li highway in 174 forest class.In the spring of 2009,the field investigation and design of the Quercus mongolica natural secondary forest was reformed and massive reformed.The band transformation bandwidth were 6m(S1),10m(S2),14m(S3),and 18m(S4).The area of the block transformation were 25m2(G1))?100m2(G2)?225m2(G3)?400m2(G4)?625m2(G5)?900m2(G6),for the same reason,CK is not remade.In June 2016,field sampling was carried out to screen out 38 indexes reflecting the effect of ecological transformation on 4 levels.The first level was the water holding characteristics of the litter,including the total volume of litter,the total natural water holding rate,the total maximum water holding rate,the total maximum water holding capacity,and the total effective storage capacity.The second level was the physical property of the soil.It includes soil bulk density,maximum water holding capacity,capillary water holding capacity,capillary porosity,non capillary porosity and total porosity.The third level is soil chemical properties,including PH,organic matter,total nitrogen,hydrolysable nitrogen,total phosphorus,available phosphorus,total potassium and available potassium.The fourth level is the analysis of the growth status of the forest,including the biological diversity layer:arbor layer,shrub layer and herb layer;photosynthesis level,including transpiration rate,net photosynthetic rate,photosynthetic effective radiation,environmental CO2 mole fraction,intercellular CO2 mole fraction,leaf temperature,stomatal conductance,seedling regeneration and growth,the growth rate and the ground diameter of all the seedlings of Pinus sibirica,Pinus sylvestris and Larix gmelinii were measured,and the survival rate and growth rate of the three seedlings were calculated.The main component analysis method was used to synthetically evaluate the transformation effect of the natural secondary forest of Quercus mongolica in Daxing'an area after the transformation of the natural secondary forest and the transformation of the massive transformation.The water holding performance,soil physical properties,soil chemical properties,biological diversity,regeneration of seedling photosynthesis and regeneration of seedling growth were studied.The comprehensive evaluation model was set up in 4 levels,which reflected the effect of ecological transformation,and the comprehensive score was calculated by the principal component analysis method.In order to evaluate the transformation effect of the transformation models of Quercus mongolica natural secondary forest.The results show that the comprehensive score of S2 and G2 samples is higher,indicating that the 10m modified strip culture and 100m2 block modified cultivation were the best,which were the most suitable for the transformation of the natural secondary forest of Quercus mongolica in Daxing'an area.The research results provide a scientific and reliable theoretical basis for the sustainable management of secondary forest in Daxing'an area.