文献类型：期刊文献

英文题名：Additive crown width models comprising nonlinear simultaneous equations for Prince Rupprecht larch (Larix principis-rupprechtii) in northern China

作者：Fu, Liyong[1,2] Xiang, Wei[3] Wang, Guangxing[4] Hao, Kaijie[5] Tang, Shouzheng[1]

第一作者：Fu, Liyong;符利勇

通信作者：Fu, LY[1];Fu, LY[2]

机构：[1]Chinese Acad Forestry, Res Inst Forest Resource Informat Tech, Beijing 100091, Peoples R China;[2]Penn State Univ, Ctr Stat Genet, Loc T3436,Mailcode CH69,500 Univ Dr, Hershey, PA 17033 USA;[3]Beijing Forestry Univ, Sch Forestry, Minist Educ, Key Lab Silviculture & Conservat, Beijing 100083, Peoples R China;[4]Southern Illinois Univ, Dept Geog & Environm Resources, Carbondale, IL 62901 USA;[5]Shanxi Acad Forestry Sci, Taiyuan 030012, Shanxi, Peoples R China

年份：2017

卷号：31

期号：6

起止页码：1959-1971

外文期刊名：TREES-STRUCTURE AND FUNCTION

收录：;WOS:【SCI-EXPANDED(收录号:WOS:000414503900017)】；

基金：We thank the Fundamental Research Funds for the Central Non-profit Research Institution of CAF (Grant No. CAFYBB2016SZ003), the Forestry Public Welfare Scientific Research Project of China (Grant No. 201404417) and the Chinese National Natural Science Foundations (Grant Nos. 31470641, 31300534, and 31570628) for financial support. We also appreciate the valuable comments and the constructive suggestions from two anonymous referees and the Associate Editor.

语种：英文

外文关键词：Adjustment in proportion; Additivity; Crown width; Nonlinear simultaneous equations; Ordinary least squares with separating regression

摘要：Crown width models developed using nonlinear simultaneous equations with a two-step procedure provided the best performance and are recommended to predict the crown components and crown width of Prince Rupprecht larch. Crown width (CW) is defined as an average of two crown diameters at two cardinal directions: east-west and south-north, obtained from measurements of four crown radii (crown components) at four directions: east, west, south, and north. CW is one of the important tree variables in forest growth and yield modeling, and forest management. Reliable estimates of CW are central elements of forest management. However, the additivity of CW and crown components and their inherent correlations have not been addressed in existing CW models. In this study, two alternative procedures for nonlinear simultaneous equations (NSE) were used to develop CW models. The procedures included a disaggregation model structure with one- and two-step, proportional weighting systems, and two commonly used additivity methods, adjustment in proportion (AP) and ordinary least squares with separating regression (OLSSR). These methods were compared using data from a total of 3369 Prince Rupprecht larch (Larix principis-rupprechtii Mayr.) trees in 116 permanent sample plots in northern China. It was found that these methods effectively ensured that the sum of the crown components was equal to twice the total CW. The NSE accounted for the inherent correlations among the crown components and CW. The CW models developed using the NSE with the two-step procedure provided the best performance, followed by the models developed with AP and OLSSR. This methodology can be adapted to develop a system of CW models for other tree species.