Biomass And Allocation Of Chinese Forest And Grassland Ecosystem

Biomass refers to the cumulative amount of net primary production of green plants per unit area in any time interval,that is,the biomass at a certain moment is the sum of the living organic mass accumulated in the ecosystem before this moment.The distribution of biomass among various organs reflects the growth strategy of plants to adapt to the environment,and the distribution between above-ground and underground biomass(root-shoot ratio,R/S)affects the entire ecosystem by affecting the soil carbon input of the ecosystem The system carbon cycle plays a vital role in the terrestrial ecosystem carbon cycle.Forest and grassland ecosystems account for a relatively large portion of terrestrial ecosystems.The accurate estimation of their biomass and dynamics is not only the basis for studying many forestry and ecological issues,but also for assessing the carbon budget of terrestrial ecosystems,compiling national greenhouse gas inventories,and nuclear The main content of the forestry carbon compensation project.Therefore,the study of biomass allocation and its influencing factors in China’s forest and grassland ecosystems provides an important reference for accurately assessing China’s forest productivity,carbon and nitrogen storage,and provides guidance for forest and grassland tending.Field investigation has been conducted in 27 primitive forest ecosystems in China from tropical rain forests to cold-temperate coniferous forests,and the specific parameters of all plant species in the grassland ecosystems of Inner Mongolia,Loess Plateau,and Qinghai-Tibet Plateau.Based on the model method,the different forest ecosystems are calculated.To estimate the biomass of different organs and grassland biomass at different levels(trees,shrubs,herbs),the above-ground part adopts the method of full shear drying and weighing,and the underground part is the method of drying and weighing by root drills,and then reverse calculation.In this study,a more scientific biomass database of China’s forest and grassland ecosystems was obtained through detailed statistical calculations.It mainly includes biomass,root-shoot ratio,biomass distribution coefficient of each organ,etc.At the same time,the climatic factors,soil factors,etc.are obtained after field measurement and collection of soil,laboratory tests,calculations and analysis.This paper analyzes the spatial distribution pattern of biomass and its allocation in typical forest and grassland ecosystems in China,and discusses the direct and indirect effects of various environmental factors on biomass allocation.The main conclusions are as follows:(1)The total biomass of a typical forest ecosystem in China is22.66kg/m~2.In the forest ecosystem,the tree layer occupies a dominant position and its biomass accounts for about 99%of the total biomass of the forest community;the total biomass of the shrub layer is 0.28 kg/m~2,accounting for 1%of the biomass of the forest ecosystem,and grassland accounts for very little in the forest ecosystem.In addition,the community and tree organs and total biomass in the forest ecosystem all present a significant hydrothermal pattern,that is,there are significant differences between different climate zones and a certain regularity from south to north,generally showing a gradual flow from north to south.Increasing trend,the biomass of shrub layer and herb layer has no significant change rule.(2)The dynamic characteristics of community biomass are the same as those of the tree layer,and the pattern of biomass and distribution ratio is also the same.The leaves have no obvious regularity,and the trunks show a gradual decrease from the cold temperate zone to the warm temperate zone,and then gradually go to the border tropics.In the increasing trend,the distribution ratio of root biomass is more obvious in the northern forests.It gradually increases from cold temperate zone to warm temperate zone,and does not change much from warm temperate zone to the south;the change rule of branch biomass distribution ratio is from cold temperate zone to north.The subtropical zone is gradually increasing,with little change to the south.(3)The Qinghai-Tibet Plateau is a grassland ecosystem with the largest underground biomass and root-to-shoot ratio among the three plateaus.The complex climatic characteristics have created a wealth of grassland types.Grasses have adopted different growth methods under diverse climatic environments,and thus are different.There are significant differences in the below-ground biomass,total community biomass,root-to-shoot ratio,and below-ground biomass proportion of grassland types,but the difference between above-ground biomass and above-ground biomass proportions is not significant.We can find that whether it is above-ground biomass The total biomass,root-shoot ratio and total biomass all show a wave bimodal curve trend that first increases,then decreases and then increases with the increase of latitude,but the change trend of above-ground biomass is not obvious.(4)Annual precipitation,annual average temperature,dryness,and soil Ph are the main factors that affect the distribution pattern of forest biomass.Important factors that affect the distribution are soil Ph,soil carbon,and phosphorus content.The multi-factors in the grassland ecosystem of the Qinghai-Tibet Plateau do not explain the biomass and its distribution coefficient very well,but a relatively single environmental factor has a very significant correlation with the biomass and the distribution coefficient.Therefore,the biomass Its distribution is the result of the interaction between various environmental factors.The influencing factors are complex.The influencing factors of the grassland biomass distribution in Tibet are comprehensive and complex.It is not a single temperature or precipitation,but the influence of extreme temperature and extreme precipitation.Play an important role.