Pinus Massoniana Plantation DBH Growth Models Including Climatic Factors In Hubei Province

Global warming has brought huge impacts on human society and ecosystems.Hubei Province is in the central part of China,with a subtropical monsoon climate dominated by alpine microclimates in some areas,which are more sensitive to climate change.At the same time,it is the main growth and distribution area of masson pine in China.The growth of masson pine is also very sensitive to climate change.This research takes the masson pine plantation in Hubei Province as the research object to carry out research with very important significance.This experiment is based on the forest resource inventory data of 9702 masson pine trees in 209 fixed sample plots that can be completely reset and the meteorological data of 90 meteorological stations in Hubei Province and surrounding areas.Hubei Province is divided into western Hubei by consulting the results of previous studies.And other regions,a single tree diameter growth model at breast height that can reflect the impact of large-scale regional climate change on the growth of single tree has been developed.The model uses four types of variables:single tree size factor(Size),competition factor(Comp),site factor(Site)and climate factor(Clim).The modeling is completed through five steps of comparison of spatial heterogeneity of experimental data,correlation analysis,stepwise regression analysis,ordinary least squares estimation and dummy variable processing.The results show:Among the single tree size factors,ln D is the main factor affecting the growth of breast diameter of Masson pine and has a significant positive effect;among the competitive factors,ln(BA)and BAL have an inhibitory effect on the growth of breast diameter,and ln(BA)is manifested in two areas Among the site factors,elevation factor Elevation has an inhibitory effect on the growth of DBH,and the degree of influence shown in the two areas is significantly different,but its standardized coefficient is the lowest,indicating that the elevation factor is not in large-scale area studies.The main factors affecting the growth of trees;among the climatic factors,the average precipitation Pgsm during the growing season and the minimum precipitation Pgsmin during the growing season both significantly promote the growth of DBH,while the highest temperature Tgsmax in the growing season has a significant inhibitory effect on the growth of DBH.Pgsm and Tgsmax also showed obvious regional differences.The determination coefficient R~2 of the single tree model I without climatic factors is 0.5335,and the determination coefficient R~2 of the model II after adding the climatic factors is 0.5792,indicating that the meteorological factors have a significant impact on the growth of masson pine,and the dummy variable method is used to deal with The coefficient of determination R2 of the single tree model III reached 0.6671,indicating that the diameter at breast height growth of Masson pine in different regions responds differently to climate change.The remaining standard deviation(S),mean error(ME),mean relative error(MRE),root mean square error(RMSE),and systematic error(TRE)of the 5 test indicators of the final model III are 3.9425,0.0045,3.96,0.5419,respectively,2.67 are in line with the standard.All in all,this modeling based on the restoration of the FCI data has achieved good results,indicating that the inventory data can objectively and comprehensively reflect the overall growth status of Pinus massoniana in Hubei Province.And through the comparison of dummy variable processing,it is proved that the regional modeling is more close to the growth and changes of masson pine in different regions.The built model provides technical support and scientific basis for forecasting and simulating the dynamic changes of forests,the update of forest resource data and the sustainable development of Hubei forestry.