Study On Growth Model And Multi-functional Simulation Of Chinese Fir Plantation

Cunninghamia lanceolata is am important timber species in the South of China.It has the characteristics of fast growth,good material and large planting area.In the background of ecological forestry,the multi-functional management technology of Cunninghamia lanceolata plantation can be used to provide key technologies and data for landscape planning,wood production and carbon sink trading of ecological functions of Chinese fir.In this paper,the growth and harvest data of different types(age,density,site)of Cunninghamia lanceolata plantation were obtained by using typical sampling method,tree stem analysis method and biomass comprehensive method in Jiangle National Forest Farm in Fujian province.In the data analysis parts,based on the comparison of the expression of a large number of growth and harvesting models at home and abroad,the models of tree base crown equations,taper models,diameter distribution models,height-diameter curve equations,crown wide models,diameter growth models,tree number models,site quality evaluation models,stand density models,form factormodels were all published in home and abroad,comparing the accuracy to select the best models,and statistic the models by Nonlinear Mixed-effects method,Nonlinearmethod and Linear method to analysis the models,and taper models and diameter models were modified reasonable to get a good accuracy.On the basis of a large number of systematic fir growth and harvesting models,the forest simulator system which was introduced in Germany was used to evaluate the volume,biomass and landscape quality of Chinese fir stands and simulate the impact of different management measures.The main conclusions of this paper are summarized as follows:(1)In the results of vertical tree height,DBH and volume growth,the growth threshold of Chinese fir was 20 years,and the base age of Chinese fir should be 20 years.The trunk grows to a chest high position that takes about 2.1 a.The number of mature ages is 34 a.Based on the geometric area of the cross section of the trunk disc,the geometric mean radius has the highest statistical accuracy in the statistical analysis of the geometric mean radius,the arithmetic mean radius,the shortest radius and the longest radius.(2)In the growth and harvest model,the optimal taper equation model for Chinese fir is d/D=(?),this expression can be described the stem shape very well,the results also showed that the more parameters in the taper equation may lead to more complex structures,which may lead to collinearity problems.There are significant correlations between the parameters a and b in the Wellbull diameter distribution function,and the parameter c has nothing to do with the age of the tree.After the improvement,the diameter distribution model is obtained.The best expression of diameter distribution model for Chinese Fir is F=1-exp(-(d/(10.34*ln(A)-12.61))2.9619).The reconstructed diameter growth equation is D=137.2830SI0.0300N-0.2340RD0.9840(1-exp(-0.0935A0.8180))The diameter,tree height,cross-sectional area and volume growth and harvesting model of single wood and stand were obtained by coupling method.(3)The forest functions models of volume,biomass and landscape quality with coefficient of forest.The best standard volume table expression is V=4.798 × 10-5 × D2 × H0.9137 Based on the analysis of biomass model and its parameters,it was found that Tree volume(TV),WD and biomass wood density conversion factor(BECF)had great influence on the estimation accuracy of biomass model,and the highest precision.The amount of expression is In(B)=-0.0703+0.9780*ln(TV)+0.0213*ln(WD)+1.0166*ln(BECF).Therefore,when TV,WD and BECF were combined with tree biomass volume coefficient bi for Chinese Fir,the stand biomass(SB)model included both volume(SV)and coefficient bi variables of the stand as follows:bi=Exp(-0.0703+0.9780*ln(TV)+0.0213*ln(WD)+1.0166*ln(BECF)).The stand biomass model is SB=SV/TV*bi.The relationship between stand landscape quality and stand average DBH is SSBE=0.21884*DBH+3.1741,The relationship between stand landscape quality and stand average height is SSBE=0.2497*H+2.6526.The relationship between tree landscape quality and DBH is:TSBE=0.4394*DBH2+1.5158*DBH+42.741;The relationship between tree landscape quality and H is:TSBE=3.6784*H1.4128;tree landscape quality and stand landscape quality relationship is SSBE=2.7076*ln(TSBE)-7.2653.When the average DBH and the average tree height were less than 8.4 cm and 9.8 m,respectively,the canopy density was negatively correlated with the forest landscape quality,that is,the higher the canopy density,the lower the forest landscape quality;The average height of DBH and forest height was more than 8.4 cm and 9.8 m,respectively.There was a positive correlation between canopy density and landscape quality.We concluded that average tree H and DBH measurements within a stand can be used to predict SSBE by extrapolating the tree-based SBE model to the stand-based SBE model.Therefore,SBE models based on individual tree measurements can provide a quantitative guide for forest landscape quality planning and evaluation.Similarly,in the experimental form,the DBH appeared in the vicinity of 8.0 cm significant demarcation point.It is concluded that the division of young trees or young stand of Chinese fir or woods is consistent,and the conclusions of the research on the related problems have the opposite conclusion.Therefore,the research of Chinese fir species should be 8.0 cm as the young tree demarcation point.(4)The newly constructed fir growth and harvesting equation is more accurate,suitable for forest simulation can be nested in the Forest simulator system,and the forest simulator system can be used to simulate the forest growth process and the simulation of management planning.Under the condition of a single variable change,the simulation results showed that,the optimum plantation tree number is 3000 at per hectare,the optimum thinning type is increment felling,the optimum thinning intensity ratio is 0.9.Under different site quality indexes,the average DBH and height difference obviously,the site quality index change from 12 to 26,the height changed 17.13 meters.But the DBH changed less than height,the data is 5.35 cm.When the simulation with regeneration model,the associated tree species were also increasing,and gradually evolved into mixed forest,the pure Chinese Fir stand replaced by the Chinese Fir mixed stand,the even-aged stand replaced by the uneven-aged stand,the diameter distribution update into negative exponential distribution at 77a.In the future,we can harvest a certain amount of target tree,to achieve forest sustainable management.