Individual Tree Crown Width Prediction Models For Main Broad-leaf Species In Natural Secondary Forest Of Maoershan Mountain

Individual tree crown width prediction models for main broad-leaf species in natural secondary forest of Maoershan mountain was developed based on a data set of 200 plots 16847 sample trees located in Maoershan experimental Forestry Farm of Northeast Forestry University.Because of the problem of obvious heterogeneity among observations taken from the different sample plots,the random effects of sample plots to crown diameter were considered,namely,developing the mixed effects crown width model.Base model that used to develop mixed model was selected from 10 models reported in the literatures,and the effects of tree factors,site factors,stand density,competition,species composition and other factors to crown diameter were considered.Results showed that the optimal base model of Betula platyphylla Suk,Tilia tuan Szyszyl.and three hardwood species in northeast China(Fraxinus mandschurica Rupr.,Juglans mandshurica Rupr.and Phellodendron amurense Rupr.) were logistic function,the optimal base model of Acer mono Maxim,and Ulmus pumila L.were an power function with an intercept,the optimal base model of Betula costata Suk.was exponential function,the optimal base model of Populus L.was linear function and the optimal base model of Quercus mongolica Fisch.ex Ledeb.was quadratic function;The average height of dominant tree(Ht),the average condition height of stand(Hd),the average height of dominant species(Hdom),the crown length(CL),the crown ratio(CR),the height to live crown base(HCB),the basal area(BA),the relative diameter(RD),the relative height(RH),the ratio of the basal area of the trees larger than the subject tree and the basal area(BAL/BA),the average diameter of dominant species(Ddom)and the the basal area proportion of the objective tree species(P)were significant factors in crown width model,and the crown width increased with the increase of Hu Hd,Hdom,CL,CR,RD,RH,Ddom and P,decreased with the increase of HCB,BA and BAL/BA;The root mean square error(RMSE) of all mixed effect models both were between 0.5m and 1.0m,the mean error(ME) both were small,the mean absolute error(MAE) both were between 0.5m and 1.0m,the adjusted coefficient of determination(Radj2) both were more than 0.7,excpect 0.6223 of Tilia tuan Szyszyl.,and the relative mean absolute error(MA%E)both were less than 20%,excpect 27.3061%of Betula platyphylla Suk.;Compared to the base model,RMSE of all mixed effect models decreased more than 20%,except the 18.1%reduction of Tilia tuan Szyszyl.and the 13.9%reduction of Populus L.Suk.,the Radj2 increased more than 25%,except the 9.9%increase of Populus L.,the MAE and MA%E decreased more than 30%,except the 22.1%reduction of Tilia tuan Szyszyl.and the 26.5%reduction of Betula costata.Because of the larger Radj2,and the smaller RMSE,ME,MAE and MA%E,all individual tree crown width mixed effect models could be applied for predicting crown width appropriately.The results of this study provided the basis for estimating crown surface area,crown volume,standing tree volume,biomass for main broad-leaf species in natural secondary forest of MAErshan mountain and so on.