Evaluation of the spatial dependence of dendrometric characteristics for an Eucalyptus plantation

ABSTRACT Geostatistics evaluates the spatial dependence between two or more variables in order to estimate unknown values in space. The objective of this study was to evaluate, using geostatistical techniques, the spatial variability of dendrometric characteristics for a commercial plantation of Eucalyptus grandis x Eucalyptus urophylla located in eastern Minas Gerais, Brazil (19º28' S and 42º49' W). The diameter at breast height (DBH) and commercial height (H) of 60 trees was measured in a forest inventory plot at two, five and seven years old. The volume of each tree in the plot was estimated from allometric equations and values of DBH and H. Spatial dependence of the three dendrometric variables at different ages was evaluated by fitting the experimental semivariogram. Validation of the semivariograms was performed using the jackknife test. The dendrometric variables analyzed presented normal distribution throughout the entire production cycle according to the Kolmogorov-Smirnov test. The spherical model adequately represented the spatial distribution of dendrometric characteristics for the planted forest. The dendrometric characteristics of the analyzed plantation had an average spatial dependence, making the use of geostatistical techniques for characterization of the plantation very important.

摘要：地质统计学（Geostatistics）通过评估两个或多个变量间的空间相关性，以估算空间中的未知数值。本研究旨在借助地质统计学技术，对位于巴西米纳斯吉拉斯州东部（南纬19°28′、西经42°49′）的巨桉×尾叶桉（Eucalyptus grandis × Eucalyptus urophylla）商品人工林的测树特征空间变异性进行评估。研究人员在林龄分别为2年、5年及7年的森林调查样地内，测定了60株林木的胸径（Diameter at Breast Height，简称DBH）与商品材高度；基于异速生长方程以及胸径、商品材高度的测定值，估算得到样地内单株林木的材积。通过拟合实验半变异函数，对不同林龄下3个测树变量的空间相关性进行评估，并采用刀切法检验对半变异函数进行验证。经柯尔莫哥洛夫-斯米尔诺夫（Kolmogorov-Smirnov）检验，本研究所分析的测树变量在整个生产周期内均符合正态分布；球状模型可较好地拟合该人工林测树特征的空间分布格局。所研究人工林的测树特征呈现中等空间相关性，因此采用地质统计学技术对该人工林进行特征表征具备重要的应用价值。