湖北省杉木人工林胸径差分方程及多形地位指数表研究

Study on DBH Difference Equation and Polymorphic Site Index Table of Chinese Fir Plantation in Hubei Province

为解决目前以胸径为指标编制的地位指数表较少,且采用胸径为因子评价立地质量是否可行的问题,选用长期积累的杉木树干解析数据拟合胸径生长方程,构建胸径的差分方程和湖北省杉木人工林地位指数表。运用精度检验和落点检验法分别对导向曲线和地位指数表进行检验与比较,评价其制表精度与适用性。研究结果表明,(1)采用解析木数据拟合胸径的基础方程与差分方程均有良好的拟合优度;(2)选择Korf基础方程与Korf差分方程,以20 a为标准年龄,2 cm为指数级,采用导向曲线法分别编制出湖北省杉木人工林单形地位指数表和多形地位指数表;(3)构建的模型与地位指数表均通过检验,且差分方程的检验精度99.61%,高于基础方程的96.97%;多形地位指数表的落点精度较单形地位指数表高1.18%。由此可见,采用差分方程编制的湖北省杉木人工林胸径地位指数表,较基础方程精度更高,更能准确地评估湖北杉木人工林的立地质量。

In order to solve the problem that there are few site index tables compiled with DBH as index and the feasibility of using DBH as factor to evaluate site quality,in this study,the DBH growth equation was fitted with the long-term accumulation analytical data of Chinese fir trunks,the difference equation of DBH and the site index table of Chinese fir plantation in Hubei Province were constructed.The accuracy test and point test were used to test and compare the guide curve and the site index table respectively to evaluate the tabulation accuracy and applicability.The results showed that,(1)both the basic equation and the difference equation using the analytic data to fit DBH had good goodness of fit.(2)using the Korf basic equation and Korf difference equation,the single form site index table and the polymorphic site index table of Chinese fir plantation in Hubei province was compiled by using the guide curve method,taking 20 a as the standard age and 2 cm as the exponential level.(3)both the established model and the site index table passed the test,and the test accuracy of the difference equation was 99.61%,higher than 96.97%of the basic equation.The polymorphic site index table was 1.18%higher than single form site index table.It can be seen that,the index table of DBH site of Chinese fir plantation in Hubei province compiled by difference equation is more accurate than the basic equation and can evaluate the site quality of Chinese fir plantation in Hubei province more accurately.