北京市主要行道树白蜡生长因子的模型研究

为了构建胸径生长估测模型，以便快速掌握行道树的生长状况，提高行道树调查效率。笔者采用随机抽样的方法，收集了北京城区主要行道树白蜡的胸径、树高、枝下高、冠幅、叶面积等生长指标，根据胸径等级进行分类，利用5种单因素变量模型构建胸径与多项生长指标的估测模型。结果表明，北京市中径级的行道树白蜡分布最为广泛，占总数的63%以上；白蜡胸径与树高的相关性最高，其余依次为冠幅、叶面积、枝下高，其指数估测模型H=98.2399-28.0859D+2.8115D²-0.0743D³，相关系数达0.9967，系统误差为0.3299%，相对其他模型效果更优；而白蜡胸径与多生长因素的估测首选模型为：D=0.5595H²-9.6656H+2.0172h²-9.2454h-1.0413W²+12.4859W-0.0188S²+1.4996S+6.2011，其均方根误差只有1.0242，而精度高达95.61%。本研究建立的白蜡胸径生长估测模型具有良好的效果，适用于各年龄段的行道树白蜡调查，为北京市行道树白蜡的生长状况、景观质量和生态效益的监测提供快速调查与数据更新理论模型。

Model Study on Growth Factors of Fraxinus in Beijing

The paper aims to acquire the growth condition and improve investigation efficiency of Fraxinus in the urban area of Beijing, and study the DBH growth estimated model. The author used random sampling method, collected the growth index of Fraxinus in the urban area of Beijing, such as DBH, tree height, under branch height, crown width, leaf area, and classified these indexes according to DBH class, constructed the estimation model of DBH and multiple growth index by using 5 kinds of single factor model. The results showed that middle diameter class of the Fraxinus were most widely used in street trees, accounting for more than 63% of the total; the correlation of DBH and height were the highest, followed by the crown width, leaf area, clear length. The best model of DBH and height was H=98.2399-28.0859D 2.8115D²-0.0743D³, whose correlation coefficient was 0.9967 and standard error was 0.3299%. The better choice of the estimation model among DBH with other multiple growth index was: D=0.5595H²-9.6656H 2.0172h²-9.2454h-1.0413W² 12.4859W-0.0188S² 1.4996S 6.2011. The standard deviation was only 1.0242, while the accuracy was up to 95.61%. The DBH growth estimation model of the wax street trees established in this study had good effect and suitable for trees of all ages, and could provide a theoretical model with fast investigation and data update for growth status of Fraxinus, landscape quality and ecological benefit in the urban area of Beijing.