文献类型：期刊文献

英文题名：Additivity of nonlinear tree crown width models: Aggregated and disaggregated model structures using nonlinear simultaneous equations

作者：Lei, Yakai[1,2] Fu, Liyong[3] Affleck, David L. R.[4] Nelson, Andrew S.[5] Shen, Chenchen[5] Wang, Mengxi[3] Zheng, Jingbiao[6] Ye, Qiaolin[7] Yang, Guowei[1]

第一作者：Lei, Yakai

通信作者：Yang, GW[1]

机构：[1]Nanjing Audit Univ, Sch Informat Engn, Nanjing 211815, Jiangsu, Peoples R China;[2]Henan Agr Univ, Coll Forestry, 95 Wenhua Rd, Zhengzhou 450002, Henan, Peoples R China;[3]Chinese Acad Forestry, Res Inst Forest Resource Informat Tech, Beijing 100091, Peoples R China;[4]Univ Montana, Dept Forest Management, Missoula, MT 59812 USA;[5]Univ Idaho, Dept Forest Rangeland & Fire Sci, Moscow, ID 83844 USA;[6]Space Informat Engn Univ, Inst Geog, Zhengzhou 450001, Henan, Peoples R China;[7]Nanjing Forestry Univ, Coll Informat Sci & Technol, Nanjing 210094, Jiangsu, Peoples R China

年份：2018

卷号：427

起止页码：372-382

外文期刊名：FOREST ECOLOGY AND MANAGEMENT

收录：;EI(收录号：20182605365400);Scopus(收录号：2-s2.0-85048860276);WOS:【SCI-EXPANDED(收录号:WOS:000440775600041)】；

基金：We would like to thank the Chinese National Natural Science Foundations (No. 61772277), the Central Public-interest Scientific Institution Basal Research Fund (Grant No. CAFYBB2016SZ003), the National Natural Science Foundations of China (Nos. 31570628, 31300534, and 31470641), and the Natural Science Foundation of Jiangsu Province (No. BK20171453) for the financial support of this study.

语种：英文

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

摘要：A tree crown is a mass of foliage and significantly correlated to biomass and growth of other parts of a tree. Crown width (CW) is defined as an average of two crown diameters perpendicular to each other, obtained from measurements of four crown radii (crown components). The CW is often used as a covariate predictor in various forest models and therefore, its accurate estimate can be useful for forest management. Although various CW models have been developed so far, all of them lack a detailed investigation of the additivity properties of crown components and inherent correlations among the components and total CW. This study compared three alternative procedures of developing the systems of CW models: nonlinear simultaneous equations (NSE), disaggregated model structure with both one-step proportional weighting system (DMS&OSPWS), and two-step proportional weighting system, and aggregated model structure with one constraint on the total CW. Other two commonly used additivity methods: adjustment in proportion and ordinary least square with separating regression were also evaluated. The comparisons were based on the analyses of data obtained from 2207 trees of Mongolian oak (Quercus mongolica Fisch.) on 116 permanent sample plots located in northern China. Results showed that each method ensured a summation of crown components equal to twice as much as the total CW. The NSE better accounted for the inherent correlations among the crown components and total CW. Out of the model structures evaluated, DMS&OSPWS provided the best performance. This article emphasized more on the methodology and it was expected that the method could be applied by other researchers to develop similar systems of the CW models for other species as well.