Study On The Spatial Distribution Pattern Of Forest Biomass And Its Influencing Factors In Xinglong Mountain

Forest vegetation plays an important function in the carbon cycle and carbon balance process of global,and its response to ecological factors such as climate and topography is extremely sensitive,and its spatial structure can reflect the adaptation mechanism of forest vegetation to local hydrothermal conditions.Biomass,as an important indicator characterizing the productivity and function of forest ecosystems,is an important component of the carbon pool of terrestrial ecosystems.The relationship between its distribution pattern and environmental factors reflects the material cycle and energy accumulation process of vegetation in forest resources,reflects the adaptation strategy and functional stability maintenance mechanism of vegetation in response to environmental changes,and helps to understand the carbon sequestration and carbon cycle mechanism of forest ecosystems.The special hydrothermal regime in the semi-arid interior provides the possibility for forest vegetation development.However,the spatial distribution pattern and formation mechanism of forest vegetation and its biomass are not clear.Given this,this study relies on the National Positioning Observation and Research Station for Forest Ecosystems in Xinglong Mountain.The forest parameters were obtained by setting up sample squares for the study of Picea wilsonii Mast,Pinus tabuliformis,Quercus wutaishansea Mary,Larix gmelinii,and Populus davidiana and Betula platyphylla.The correlation between forest vegetation distribution characteristics and climatic and topographic factors was analyzed by random forest method,biomass anisotropy equation,support vector regression,and through path analysis.The biomass characteristics and influencing factors of major forest types were studied,and the spatial distribution patterns of forest biomass and environmental response mechanisms were explored.To provide the scientific basis for forest ecosystem management and conservation and decision-making.The results of the study are as follows.（1）The distribution range of forest vegetation in the Xinglong Mountains has obvious spatial variability.The forest vegetation is mainly distributed in the area with slope direction 0-45°∩315-360°,altitude 2400-2800 m,slope 20-35°,plan curvature 10-30 and profile curvature 0-15.The trend of substitution of Quercus wutaishansea Mary-Populus davidiana and Betula platyphylla-Pinus tabuliformis and Larix gmelinii-Pinus tabuliformis with the increase of elevation.Quercus wutaishansea Mary and Populus davidiana and Betula platyphylla are mainly distributed in the area where the plan curvature and profile curvature class is 1-3.Picea wilsonii Mast,Pinus tabuliformis and Larix gmelinii are mainly distributed in areas with plan curvature and profile curvature classes of 2-6.With the change of slope direction and slope gradient,there are obvious differences in the trend of area share change of the five forest vegetation species.（2）The biomass of forest vegetation in Xinglong Mountains was ranked as Picea wilsonii Mast>Pinus tabuliformis>Quercus wutaishansea Mary>Larix gmelinii>Populus davidiana and Betula platyphylla.The biomass was significantly positively correlated（P<0.05）with soil organic carbon content,elevation,soil moisture,and net primary productivity of vegetation,and highly significantly negatively correlated（P<0.01）with soil temperature.The through-path analysis showed that the factors that had higher combined ranking on the effects of Picea wilsonii Mast,Pinus tabuliformis,Quercus wutaishansea Mary,Larix gmelinii and Populus davidiana and Betula platyphylla.The biomass were vegetation net primary productivity and soil temperature in 0-10 cm soil layer,soil organic carbon content and plane curvature in 10-20 cm soil layer,soil organic carbon in 0-10 cm soil layer and 20-40 cm soil layer,vegetation net primary productivity and latent heat flux,vegetation net primary productivity and soil organic carbon in 20-40 cm soil layer,respectively.（3）The biomass of forest vegetation ranged from 40-200 t·hm^-2,with patchy mosaic distribution.Vegetation biomass showed positive spatial correlation characteristics（Moran’I=0.129）and weak spatial autocorrelation.The factors influencing biomass in descending order are elevation,soil moisture,slope,plan curvature,soil temperature,and profile curvature,and the optimum distribution intervals were 2400-2700 m above sea level,25%-32%soil moisture,20-35°slope,20-35°plane curvature,0-20 profile curvature,and 8-12℃soil temperature,indicating that the topographic conditions and the local environment shaped by them were important factors affecting the biomass of forest vegetation.