Study On The Effect Of Site Factor And Stand Structure On Biomass Of Phyllostachys Pubescens Forest

The biomass of moso bamboo forest is the basis of matter cycle in bamboo forest ecosystem,and it is also an important index to evaluate productivity and measure management level of bamboo forest.The accumulation of bamboo forest biomass is a complex process affected by multiple factors.however,existing studies generally analyze its direct effect on bamboo forest biomass from the site factor or stand structure single aspect,ignoring the relationship between site factor and structure factor and its indirect effect on bamboo forest biomass.In this study,52 sample plots were set up in 10 counties(districts)in the east,south,west,north and central of Zhejiang province with less human interference.The combined effect of site factors and stand structure forest on biomass was analyzed by the method of random forest and structural equation model.Firstly,random forest was used to select the dominant factors from site factors and stand structure,and then the structural equation model of biomass and dominant factors was established to reveal the direct,indirect and total effects of dominant factors on biomass of bamboo forest.The main results are as follows:(1)The biomass of moso bamboo is influenced by site factor,non-spatial structure and spatial structure.The factors influencing biomass of bamboo forest are not independent of each other,but there is a certain internal relationship,which affects the biomass of bamboo forest together.(2)By using random forests,the dominant factors affecting the biomass of bamboo forest in site factors and stand structures were revealed,including culm density,mean DBH,competition index,soil thickness and altitude.The influence of stalk structure on biomass of bamboo forest is small,but there is a close relationship between stalk structure.(3)The structural equation model is applied to show that the site factor has indirect influence on the biomass of bamboo forest by influencing the stand structure,and the interaction between stand structures has indirect influence on the biomass of bamboo forest.(4)As the main component factor of bamboo forest biomass,the culm density and mean DBH are most closely related to bamboo forest biomass.The altitude,soil thickness and spatial structure competition index mainly affect bamboo forest biomass indirectly through affecting culm density and mean DBH.(5)In the management of moso bamboo,reasonable culm density and the level of stand competition should be taken into account on the premise of considering the effect of site factors in order to improve the biomass of bamboo forest.