Site Quality Classification And Growth Potential Estimation Of Phyllostachys Edulis Based On DBH/height

Moso bamboo（Phyllostachys edulis）is the most widely distributed economic bamboo species in China.Chinese scholars have done a lot of research on the growth and cultivation of moso bamboo.However,due to the difference of the site area caused by climatic factors,the growth conditions of moso bamboo under different natural conditions are also different.Aiming at the growth status of moso bamboo under different environmental conditions and the relationship between different environmental factors and DBH of moso bamboo,the pure forest of bamboo in Yong`an City,Fujian Province,Huangshan City,Anhui Province,Shunan Bamboo Sea of Changning County,Sichuan Province and Yixing City,Jiangsu Province were selected as experimental forests.This paper investigates the DBH,height and density of bamboo,and investigates local climatic and topographic factors.By introducing dumb variables to classify the fitting model,principal component analysis and stepwise regression to screen variables,the purpose is to fit and optimize the height-DBH growth model of moso bamboo,explore the relationship between site factors and DBH of bamboo,and establish a site factor based on site factors of bamboo.Then,establish a grading system for site quality evaluation of Phyllostachys pubescens based on site factors.The results are as follows:（1）The height-DBH model of moso bamboo was fitted and optimized by introducing dumb variables.Nine commonly used growth fitting models were selected,and the optimal model was selected by model selection method to introduce hierarchical dumb variables.Logistic model can be used as the basic model for height-DBH growth of Moso Bamboo in the main distribution areas of China.In Fujian,Anhui,Sichuan and Jiangsu provinces,bamboo can be divided into 5,12,11 and 10 grades.The coefficient R²of the model is increased from 0.548,0.601,0.564,0.630 to 0.901,0.978,0.984 and 0.991,respectively.When making a unified study on Phyllostachys pubescens in four provinces,the determination coefficient R2 of the model was raised from 0.571 to 0.982,which greatly improved the accuracy of the fitting model.（2）Annual average temperature,annual precipitation,monthly average temperature,average temperature in shooting period（March,April and May）,precipitation in July,August and September,and GDD₁₀have important effects on the growth of moso bamboo,but the response degree of bamboo to climate factors is different in different regions.（3）The topographic and geomorphological factors such as elevation,slope direction,slope position,aspect,soil type and soil thickness have important effects on the growth of moso bamboo.The best fitting models of DBH-topographic and geomorphological factors of bamboo are different with different topographic and geomorphological factors.The best fitting model of DBH-topographic and geomorphological factors of bamboo in Fujian Province is as follows:D（28）0.119?（7）P os（8）（10）0.803?（Thc）（10）8.136.The best fitting model of DBH-topographic and geomorphological factors of bamboo in Anhui Province is as follows:D（28）0.2 87?（7）E lv（8）（10）0.3?（7）Pos（8）-0.221?（7）A sp（8）-0.374?（7）Typ（8）（10）9.608.The best fitting model of DBH-topographic and geomorphological factors of bamboo in Sichuan Province is as follows:D（28）-0.2 39?（7）E lv（8）（10）0.108?（7）Pos（8）-2.417?（7）Ty p（8）（10）0.580?（7）Thc（8）（10）16.279.The best fitting model of DBH-topographic and geomorphological factors of bamboo in Jiangsu Province is as follows:D（28）-0.395?（7）Slo（8）（10）10.645.（4）Soil factors such as total nitrogen,alkali-hydrolyzed nitrogen and organic matter have important effects.Fujian moso bamboo is mainly affected by total nitrogen,organic matter,alkali-hydrolyzed nitrogen and soil p H;Anhui moso bamboo is mainly affected by total nitrogen,alkali-hydrolyzed nitrogen,organic matter and total phosphorus;Sichuan moso bamboo is mainly affected by alkali-hydrolyzed nitrogen,organic matter,total nitrogen and soil p H;Jiangsu moso is mainly affected by alkali-hydrolyzed nitrogen,total nitrogen,organic matter and soil p H.The method of introducing dumb variable classification can significantly improve the accuracy of site quality evaluation of moso bamboo.Climate,topography and soil factors are closely related to the growth of moso bamboo,and the response of bamboo to site factors is different in different regions.The results provide a new method for site quality evaluation and production potential prediction model of bamboo.