A new model for predicting the total tree height for stems cut-to-length by harvesters in Pinus radiata plantations  

作　　者：Chenxi Shan Huiquan Bi Duncan Watt Yun Li Martin Strandgard Mohammad Reza Ghaff ariyan 

机构地区：[1]School of Information Science and Technology,Beijing Forestry University,Beijing 100083,People’s Republic of China [2]Forest Science,NSW Department of Primary Industries–Forestry,Level 12,10 Valentine Ave,Parramatta,NSW 2150,Australia [3]School of Ecosystem and Forest Sciences,The University of Melbourne,Parkville,VIC 3010,Australia [4]Snowy Region,Forestry Corporation of NSW,76 Capper Street,Tumut,NSW 2720,Australia [5]Australian Forest Operations Research Alliance(AFORA),University of the Sunshine Coast,Sippy Downs,QLD 4556,Australia

出　　处：《Journal of Forestry Research》2021年第1期21-41,共21页林业研究（英文版）

基　　金：Forest and Wood Products Australia Limited(FWPA)through project PNC465-1718:Advanced real-time measurements at harvest to increase value recovery and also supported by Beijing Forestry University through the special fund for characteristic development under the program of Building World-class University and Disciplines.

摘　　要：A new model for predicting the total tree height for harvested stems from cut-to-length(CTL)harvester data was constructed for Pinus radiata(D.Don)following a conceptual analysis of relative stem profi les,comparisons of candidate models forms and extensive selections of predictor variables.Stem profi les of more than 3000 trees in a taper data set were each processed 6 times through simulated log cutting to generate the data required for this purpose.The CTL simulations not only mimicked but also covered the full range of cutting patterns of nearly 0.45×106 stems harvested during both thinning and harvesting operations.The single-equation model was estimated through the multipleequation generalized method of moments estimator to obtain effi cient and consistent parameter estimates in the presence of error correlation and heteroscedasticity that were inherent to the systematic structure of the data.The predictive performances of our new model in its linear and nonlinear form were evaluated through a leave-one-tree-out cross validation process and compared against that of the only such existing model.The evaluations and comparisons were made through benchmarking statistics both globally over the entire data space and locally within specifi c subdivisions of the data space.These statistics indicated that the nonlinear form of our model was the best and its linear form ranked second.The prediction accuracy of our nonlinear model improved when the total log length represented more than 20%of the total tree height.The poorer performance of the existing model was partly attributed to the high degree of multicollinearity among its predictor variables,which led to highly variable and unstable parameter estimates.Our new model will facilitate and widen the utilization of harvester data far beyond the current limited use for monitoring and reporting log productions in P.radiata plantations.It will also facilitate the estimation of bark thickness and help make harvester data a potential source of taper data to reduce the i

关 键 词：Stem profi les Cut-to-length simulations Harvester data Model construction Nonlinear multipleequation GMM estimation Benchmarking prediction accuracy 

分 类 号：S758.5[农业科学—森林经理学]