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    王妍, 杨华, 李艳丽, 邱实. 基于结构方程模型的林木竞争指标研究[J]. 北京林业大学学报, 2015, 37(4): 28-37. DOI: DOI:10.13332/j.1000-1522.20140075
    引用本文: 王妍, 杨华, 李艳丽, 邱实. 基于结构方程模型的林木竞争指标研究[J]. 北京林业大学学报, 2015, 37(4): 28-37. DOI: DOI:10.13332/j.1000-1522.20140075
    WANG Yan, YANG Hua, LI Yan-li, QIU Shi. Tree competition index based on the structural equation model[J]. Journal of Beijing Forestry University, 2015, 37(4): 28-37. DOI: DOI:10.13332/j.1000-1522.20140075
    Citation: WANG Yan, YANG Hua, LI Yan-li, QIU Shi. Tree competition index based on the structural equation model[J]. Journal of Beijing Forestry University, 2015, 37(4): 28-37. DOI: DOI:10.13332/j.1000-1522.20140075

    基于结构方程模型的林木竞争指标研究

    Tree competition index based on the structural equation model

    • 摘要: 为了研究竞争指标之间的关系,本文基于长白山林区云冷杉针阔混交林的典型样地数据,选取12个可测指标并分为3类,即林木距离指标(简单竞争指标、竞争指标ME、竞争指标A、竞争木株数控制指标)、林木树冠指标(生长空间指数、生长空间竞争指数、伸展度、圆满度、投影比)和林木相对大小指标(相对胸径、相对树高、相对冠幅)进行信度检验和效度分析,并通过构建结构方程模型从总体层面对这3类林木竞争指标进行评价。结果显示:林木距离竞争指标的变幅较大、离散程度适中且一致,在结构方程中具有较为一致的显著正相关影响效用,林木距离指标的信度和效度最高,表明内在一致性最强且能够最真实地反映林木竞争状况;林木树冠各竞争指标离散程度和影响度差异较大,信度和效度相对较低,表明冠幅竞争指标的一致性、反映林木竞争状况的真实性较低,而且受到林木距离指标的影响;林木相对大小各竞争指标的变幅、离散程度、影响效用、信度和效度的变化介于林木距离指标和林木树冠指标之间,而且受到林木距离指标和林木树冠指标的影响。由此可知,与林木距离有关的竞争指标较为稳定和可靠,与林木相对大小有关的竞争指标次之,与林木树冠有关的竞争指标波动性较大。

       

      Abstract: In order to investigate the relationships between various competition indices and their effects on forest structure, 12 different tree competition indices were selected and divided into three categories: tree distance, tree crown and tree relative size indices. The analysis was based on data from a field plot of a spruce-fir mixed broadleaf-conifer forest in the Changbai Mountain area. Statistical analysis involving a structural equation model (SEM) was used to evaluate the reliability and validity of these three categories of competition indices. The results show that tree distance indices show greater variation, while dispersion degrees are moderate and consistent. Correlation effects in the structural equation model are significantly and consistently positive. Our reliability analysis and a validity analysis reveal that tree distance indices exhibit superior internal consistency and the greatest potential to reflect the real tree competition. Tree crown indices show a high degree of variability and the reliability and validity values are the lowest. The tree crown indices were also correlated with the tree distance indices. The performance of the tree relative size indices, regarding variability, degree of dispersion, correlation effects, reliability and validity are between the tree distance and tree crown indice performances. The tree relative size indices are related to distance and crown indices. The conclusion is that tree distance-dependent competition indices are more stable and reliable, tree size-related indices are in second place, while tree crown-related competition indices are rather volatile, which can be expected as tree crowns are usually measured with error.

       

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