Study On Growth And Yield Model And Maturity In Economic Revenue For Eucalyptus Timber Plantation

The forest growth prediction model is used to describe the growth status of standings by one or a group of mathematical functions,including the relationship between stand age,site factor,stand density index,forest breakage area and stand stand.Forest maturity is an important management index for judging whether the forest harvest is cost-effective in the process of forest management.It plays a decisive role in determining the age of the cuttings of the stands,which is one of the key links in the management of industrial timber.It is related to whether the forest resources are reasonably used,Directly affect the economic benefits of operators.Based on the survey data of 1 to 7 years from January 2001 and October 2016,the survey data of Shiling Forestry Farm,Beipo Forest Farm and Jijia Forest Farm,1 year to 7 years,were divided into 0.5 years,Using SPSS 19.0,ForStat 2.0,Excel 2010 established the state-owned Leizhou Forestry Bureau Eucalyptus 1 stand growth prediction model.According to the forest management technology index of the state-owned Leizhou Forestry Bureau,the market price of timber is determined by the net present value method,the annual value method,the internal rate of return and the net profit of the land.Economic maturity.Based on the forecasting model of forest growth and harvest,this paper provides a theoretical basis for the forest forest management plan and the dynamic monitoring of forest stand in the state-owned Leizhou Forestry Bureau.It has certain practical significance.The main contents are:(1)Estimation model of stand growth and harvesting:Considering the characteristics of eucalyptus fast-growing,the growth gap between the adjacent ages is larger than that of the annual growth harvesting model.The Eucalyptus plantation growth prediction model 6 months is 0.5 years for the model,can reflect a number of time nodes of the forest growth process.In this paper,the estimation model of variable density stand growth was established.The status index model,the stand density index model,the forest segmentation area model were established by using the stand age,status index and stand density as the main independent variables.Harvesting model of stand.The traditional guide curve method is used to fit the dominant high-order curve,and the best Logistic curve with the fitting effect is selected as the guide curve from the eight guide curves.The position index model is obtained by the conparative advantage L=(14.54×H_T)/(18.5094/(1+8.5045exp(-1.1150t)).The b valueis b = 1.605,which is based on the density index of the stand and the scatter plot of the age.The nine model curves are selected with the age as the independent variable and the density index as the dependent variable.Best for Gompertz curves is SDI = 1938.5559exp(-3.9794e-1.0020).The results show that the Schumacher model is better than the Richard model by using the Richard model and the Schumacher model,which is the independent variable,the stand value of the stand and the Schumacher model.,The forest breast area model is G = e-5.395-0.027/t SDI1.091-0.059/tL0.005.The age,status index and stand per hectare were the independent variables,and the standings were accumulated as the dependent variable,and the Schumacher model was used,is M = e0.622+0.032L-0.365t-1G1.3(2)Determination of economic maturity:The growth period of the forest stands was calculated by the growth model of the stand growth curve.The average age and the annual growth curve were the highest Age,calculated under different site conditions,the number of mature age of 3.5-4 years.According to the state-run Leizhou Forestry Bureau,the forest production input and output technical indicators,timber market sales through the net present value method,the annual value method,the net income of land,the maximum rate of internal rate to determine the Eucalyptus 1 to large diameter for the training objectives of the economy Mature age,respectively,6 years.When the pulp material is used to cultivate the target,the economic maturity is calculated by the net present value method,the annuity value method,the net land profit and the internal profit rate,respectively,for 6 years.