The Study Of Crown Width Prediction Models And Crown Length Prediction Models For Larix Olgensis And Fraxinus Mandshurica In Mixed Plantation

As an important part of the tree,the crown plays an important role in the growth and vitality of the tree.Therefore,it is of great significance to study the crown width and crown length.Based on the data of 3164 Larix olgensis sample trees and 3574 Fraxinus mandshurica sample trees from 24 permanent sample plots with four kinds of mixed proportion(1:1?5:3?5:5?6:4)in mixed plantation from Maoershan Forest Farm and Yimianpo Forest Farm in Shangzhi Administrative Bureau of National Foresntry Cente,Heilongjiang Province,the crown width models,the crown length models and height to crown base models for Larix olgensis and Fraxinus mandshurica were developed.By analyzing the variation rules of crown width,the crown length and height to crown base of Larix olgensis and Fraxinus mandshurica in different mixed stands and the relationship between crown width with forest competition factors,the mixed proportion and the tree position in the mixed strip were taken as dummy variables,and other tree variables and stand variables were added.The crown width models,the crown length models and height to crown base models of Larix olgensis and Fraxinus mandshurica were developed.The additive crown width models and the compatible crown length models were developed according to the optimal dummy variable models,and the fitting effect of the models were evaluated.Research indicates:(1)The crown width,crown length and height to crown base of Larix olgensis and Fraxinus mandshurica were different in different mixed proportion and different position in the mixed strip,and the stand with the mixed proportion of 5:3 is more conducive to the growth of the crown,and the canopy of Fraxinus mandshurica grew better in the side rows,and the crown of Larix olgensis grew better in the middle rows with the increase of DBH.The results showed that the ratio of tree diameter at breast height to dominant tree diameter(DDH)and the ratio of tree height to dominant tree height(HDH)were positively correlated with crown width and crown length,and the basal area of larger trees(BAL)was negatively correlated with crown width and crown length,and the ratio of tree height to dominant tree height(HDH)and the ratio of tree diameter at breast height to dominant tree diameter(DDH)and were negatively correlated with height to crown base,and the basal area of larger trees(BAL)was positively correlated with height to crown base.(2)For the crown width models of Larix olgensis and Fraxinus mandshurica with the dummy variable Zi and K,the Ra2 were 0.5642 and 0.5459.For the crown width models of Larix olgensis and Fraxinus mandshurica with the tree variables and stand variable,the Ra2 were 0.6745 and 0.5896.Based on the optimal dummy variable models of crown width,the additive crown width models of Larix olgensis and Fraxinus mandshurica were developed.The Ra2 of the addititive crown width models of Larix olgensis was 0.6721.The Ra2 of the additive crown width models of Fraxinus mandshurica was 0.5896.(3)For the crown length models of Larix olgensis and Fraxinus mandshurica with the dummy variable Zi and K,the Ra2 were 0.4259 and 0.4029.For the crown length models of Larix olgensis and Fraxinus mandshurica with the tree variables and competition factor,the Ra2 were 0.5083 and 0.4740.For the height to crown base models of Larix olgensis and Fraxinus mandshurica with the dummy variable Zi and the Ra2 were 0.7323 and 0.5948.For the height to crown base models of Larix olgensis and Fraxinus mandshurica with the tree variables and competition factor,the Ra2 were 0.8309 and 0.6445.Based on the optimal dummy variable models of crown length and height to crown base,the compatible crown length models of Larix olgensis and Fraxinus mandshurica were developed-The Ra2 of the crown length model and the height to crown base model of Larix olgensis were 0.5165 and 0.7846.The Ra2 of the crown length model and the height to crown base model of Fraxinus mandshurica were 0.3940 and 0.5878.The crown width models and the crown length models of Larix olgensis and Fraxinus mandshurica developed in this study have good fitting effect and prediction accuracy,and provide a basis for further study on the crown structure in mixed plantation.