塞罕坝华北落叶松人工林地位指数模型

A site index model for Larix principis-rupprechtii plantation in Saihanba,north China

运用传统地位指数模型来估计不同立地类型人工林立地指数是非常困难的,本文主要目的是建立适用于不同立地条件的地位指数模型,并对其立地质量进行评价.以两类调查数据和173块临时样地数据为基础,构建基于数量化理论方法Ⅰ的非线性混合地位指数生长模型.结果表明：海拔、坡向、土层厚度及土壤类型是影响华北落叶松人工林优势高生长的主要限制性因子;建立了主要限制性立地因子与林分优势高的线性回归方程,确定系数为0.912;确定华北落叶松人工林基准年龄为20年,对主要立地类型非线性地位指数混合模型参数进行了估计,模型确定系数R2均大于0.85,预测值与真实值绝对误差（e）在-0.43-0.45范围内,平均均方根误差（RMSE）在0.907-1.148范围内,模型拟合精度较高;主要立地类型优势高预测值与实际值估计误差在[-0.95,0.95]置信区间内,其中高海拔-阴坡-砂壤-中土层类型立地质量最高,其次为高海拔-阳坡-砂壤-中土层、低海拔-阴坡-砂壤-中土层,低海拔-阳坡-砂壤-中土层类型立地质量最差.

It is often difficult to estimate site indices for different types of plantation by using an ordinary site index model. The objective of this paper was to establish a site index model for plantations in varied site conditions,and assess the site qualities. In this study,a nonlinear mixed site index model was constructed based on data from the second class forest resources inventory and 173 temporary sample plots. The results showed that the main limiting factors for height growth of Larix principis-rupprechtii were elevation,slope,soil thickness and soil type. A linear regression model was constructed for the main constraining site factors and dominant tree height,with the coefficient of determination being 0. 912,and the baseline age of Larix principis-rupprechtii determined as 20 years. The nonlinear mixed site index model parameters for the main site types were estimated（ R^2〉0.85,the error between the predicted value and the actual value was in the range of-0.43 to 0.45,with an average root mean squared error（ RMSE） in the range of 0.907 to 1.148）. The estimation error between the predicted value and the actual value of dominant tree height for the main site types was in the confidence interval of [-0.95,0.95]. The site quality of the high altitude-shady-sandy loam-medium soil layer was the highest and that of low altitude-sunny-sandy loam-medium soil layer was the lowest,while the other two sites were moderate.