Simulation Of Carbon Balance Of Forest Ecosystems In Daxing'an And Xiaoxing'an Mountains

The Integrated Biosphere Simulator (IBIS) is one of the most sophisticated models in simulating terrestrial biosphere processes based on dynamic vegetation schemes. IBIS is designed to integrate a variety of terrestrial ecosystem phenomena within a single, physically consistent model that can be directly incorporated within AGCMs. To facilitate this integration, the model is designed around a hierarchical, modular structure and uses a common state description throughout.For the purposes of validating IBIS, climate and vegetation database have been set up, and the IBIS, which has been improved.With supports of database and IBIS model, we applied it in Mao'er mount forest ecosystem orientation research station of Northeast forestry university, comparisons between simulated secondary forests carbon fluxes and actual measurement data showed that the model was capable of simulating CO₂ flux. On the basis of this analysis, simulation would extend to regional scale form local spot. Carbon fluxes, such as net primary production (NPP), soil respiration and net ecosystem production (NEP) from 2004 to 2005 have been quantified in the studying area. This study aimed to not only evaluate forest ecosystem carbon budgets in study areas and provided a basis for establishing coupling model which was applicable to forest ecosystem of China. It estimated results have suggested that:In this study, using the inventory and meteorological data in Daxing'anling and Xiaoxing'anling of northeastern China during 2004 - 2005 and IBIS, we quantified the net primary production (NPP) and its spatio-temporal distribution in this region. The mean NPP was 494.7gC·m^-2·a^-1,absorbing 0.06PgC·a^-1 from the atmosphere in the whole region. The highest vegetation type of the annual NPP per unit area was temperate softwood forest, which was 577.2gC·m^-2.The highest vegetation type of the total annual mean NPP was temperate mixed coniferous and broad-leaf forest (equivalent to 17.001×10⁶tC·a^-1), which accounted for 27.16%.The spatial distribution of the mean NPP was affected by heat regime, which increased from north to south in Daxing'anling region, and well-distributed in Xiaoxing'anling region except Sunwu and Xunke.Based on datasets and IBIS, the terrestrial soil respiration and its spatial-temporal change in Da and Xiaoxing'anling during 2004-2005 were studied. As a result, a total annual mean soil respiration was 39.262×106tC·a^-1 (equivalent to 0.04PgC·a^-1) and the annual soil respiration per unit area was 317.3gC·m^-2·a^-1.The highest vegetation type of the annual soil respiration per unit area was temperate softwood forest, which was 412.5gC·m^-2·a^-1.The highest vegetation type of the total annual mean soil respiration was cold temperate deciduous coniferous forest (equivalent to 10.947×106tC·a^-1), which accounted for 27.88%. The distribution of annual mean soil respiration was obvious, which was decreased from north to south in Daxing'anling and well-distributed in Xiaoxing'anling.Based on datasets and IBIS, the terrestrial net ecosystem production (NEP) and its spatial-temporal change in Da and Xiaoxing'anling during 2004-2005 were studied. As a result, theannual NEP per unit area was 313. 4gC·m^-2·a^-1 and a total annual mean NEP was 38.779×10⁶tC (equivalent to 0.04PgC), which accounted for 27% of the Northeast forest's total. The highest vegetation type of the annual NEP per unit area was temperate mixed coniferous and broad-leaf forest, which was 370.8gC·m^-2·a^-1.The highest vegetation type of the total annual mean NEP was temperate mixed coniferous and broad-leaf forest (equivalent to 11.016×l0⁶tC·a^-1), which accounted for 28.25%.The forest ecosystem in study areas was carbon sink in the period. The distribution of annual mean NEP was obvious, which was increased from north to south in Daxing'anling and well-distributed in Xiaoxing'anling. The spatial-temporal change of annual NEP in study areas was distinct. During 2004-2005, the annual NEP of Xunke, Sunwu, Jagedaqi and Songling areas were decreased and the annual NEP of other places in study areas was increased. By analysis, quantity of heat and precipitation leaded to this result.On the whole, though a series of numerical simulation in forest ecosystem of China, it could be concluded that IBIS may be a good choice for carbon simulation in China, with its good performance. Meanwhile, improvements and advancements are still needed for the model, especially incorporated within AGCMs. Combined macro and micro methods is the further study priorities on forest carbon cycling simulation.