基于差分法的"欧美107杨"人工林单形及多形地位指数表编制OA

This study develops anamorphic and polymorphic site index tables for the Populus×euramericana'Neva'plantation in Shandong Province,aiming to provide a foundational reference for optimizing the quality of poplar plantations in this region.Using 93 analytic and average dominant trees(providing 706 height-age pairs)collected across 15 cities in Shandong Province,selecting the Richards function as the height guide curve,this study determines the reference age based on coefficients of variation in tree height for each age class,and applies the difference method to develop the guide curve,resulting in both anamorphic and polymorphic site index curve models.It estimates parameters using the Marquardt iterative method,and applies height data for the exponential function and each age class to the respective single form and polymorphic index curve models.Consequently,it creates the anamorphic and polymorphic site index tables for Populus euramericana plantations in Shandong province,the applicability of which is evaluated using the paired T-test and(PN1).The results show that(1)The Richards function demonstrates a good fit as a tree height guide curve,with a coefficient of determination of 0.878 and a relative total error of 0.17%;(2)The reference age is determined to be 8 years,with an exponential class interval of 2 meters and an age class interval of 1 year,comprising 7 exponential classes(10 to 22);(3)Both anamorphic and polymorphic site index tables pass the applicability test,with PN1 values of 81.03%and 89.21%,respectively,and the forecast accuracy of the polymorphic site index table is higher than that of the anamorphic site index table.Both anamorphic and polymorphic site index tables for Populus euramericana plantation based on the difference approach can objectively assess the site quality of these plantations in Shandong Province.