| As main part of global terrestrial ecosystem, forest is a momentous carbon (C) stock of C cycle. While forest plantation is an important part of forest ecosystem, and is one of the most vital mediums for global increaseing C sink so far. For plantation ecosystem, knowing its C accumulation condition and spatial-temporal distribution law well can help assessing and forecasting the dynamic process of forest stand growth and development, which can provide sufficient theory and practice basis for scientific and rational stand management in future. Base on field inventory, stem analysis and biomass measurement data, we estimated the whole ecosystem C density of Larix olgensis Henry.plantation in Langxiang bureau (in Lesser Khingan Mountains, Heilongjiang, northeast of China), with cluster-plots sampleing method from Forest Inventory and Analyse (FIA) under American Forest Inventory Monitoring system (FIM) and C concentration determinated by a Multi CN Analyzer (ELEMENTAR Vario EL III, Germany). Meanwhile, Larix olgensis growth and yield model was embedded in to FFE-FVS after deeply analysis about its construction, also we set and adjusted some related parameters or coefficients, then triggered the FFE-FVS to simulated the growth process of plantation and putout estimations of community biomass and ecosystem C density, which experimented forest management and other disturbs as windstorm. The following three conclusions were obtained:(1) The counting of biomass and C density of Larix olgensis plantation were estimated. On the account of relative growth theory, we built high predicting accuracy biomass model to estimate vegetation biomass, and volume accumulation of down dead materials (DDM) was converted to biomass via bulk density and decay rate. We figured out the biomass of Larix olgensis plantation community was202.843t·hm-2, including vegetation live biomass156.704t·hm-2and DDM biomass46.139t·hm-2, in which arbor biomass was in the absolute dominance position with accounting of136.225t·hm-2and corresponding proportion of67.16%. Meanwhile. we determinated C concentrations of different organs and/or components of biomass. and the average C concentrations of Larix olgensis plantation community was45.8%, which was calculated from weighted averages of arbor47.6%, snag44.6%, understory vegetation44.1%, down woody material41.2%and forest floor37.4%. Soil organic C was19.538g·kg-1. Sum of all these pools, the total C density of Larix olgensis ecosystem was185.327t C·hm-2on average, which increased with stand age and the spacial distribution was arrayed as:soil (91.847t·C·hm-2)> vegetation (74.450t·C·hm-2)> down dead materials (19.029t·C·hm-2). The annual net C increment of Larix olgensis ecosystem was5.021t C·hm-2·yr-1, and that of trees was3.479tC·hm-2·yr-1.(2) The procedure of the determining basic parameters, building of growth and yield model and estimation method of biomass in FFE-FVS system were finished. This research provided the three main data documents, including location file, stand data and sampling tree data. We also established site index table and reasonable density table to provide site index, stand density index and crown competition factor and other parameters for the operation of FFE-FVS system. The growth and yield model system construction of Larix olgensis completed, which consist of seven models followed by:DBH-height model, bark factor model, DBH growth model, height growth model, canopy growth model, stand mortality model and volume equation. Of FEE-FVS system, the arbor biomass was estimated by biomass equations of organ and components as trunk, stem, branch, canopy, root, etc. Understory vegetation biomass was estimated directly by stand age. Snag was created by stand mortality model, and its biomass was converted from volume as described above. Canopy falling, snag loss and residual piles after harvest were all origins for coarse woody debris and other types of DWM. To the forest floor, the litter layer was the sum of falling foliages of vegetation, and duff layer was transformed from the decay part of all DWM. Done with all these preparing work, we embedded the growth and yield models and biomass algorithm in original FFE-FVS, and finished the design and localization work of FFE-FVS after testing run and debugging for several times.(3) The simulator of forest growth process and estimations of biomass and C density of Larix olgensis plantation were finished by localized FFE-FVS system. Based on the chinesization window operating interface of SUPPOSE, we took simulation result of one stand as an example to check the simulator system, then reconciled the differences between estimators and true values via growth parameters, to improve the simulation accuracy. According to practical forest managements, we simulated the growth of plantation under human disturbance, and confirmed that the below thinning practice with30%intension and 10-year-interval was suitable for Larix olgensis plantation here. Meanwhile, biomass estimation was close to measured values, both had similar increase tend. Correspondingly, ecosystem C density calculations were similar to true values, and the spacial array of occupied portion for the three main pools as soil (46.61%)> vegetation (42.62%)> DDM (10.77%) with minor differences compared to true values.Our study was the first introduction of FIA cluster-plots sampling method in China, and proposed meticulous feasible field investigation methods and standard data analysing process, enhanced the accuracy and reliability of C density estimation. Meanwhile, the localized FFE-FVS simulation system for simulating stand develepment operated smoothly, with plenty of output information. It had also been proved that this sinicized simulator system was feasibile, accurate and practical, which was useful for plantation management, and estimation of biomass and C density. This study extends based materials about biomass and C density of Larix olgensis plantation in Lesser Khingan Mountains, also is important in reference to other current studies, and would help to improve monitoring system of C storage in China. |
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