Simulation On Hulunber Meadow Steppe Ecosystem Carbon Cycle Dynamic And Future Climate Scenario Analysis

As an important grassland type,temperate meadow steppe distributes widely in the East Eurasia continent.Recently,the eddy covariance flux approach,with its advantages of high time frequency,accuracy,principle and adaptability for continuous measurement,is an emerging technology for quantitative research on carbon cycle in grassland ecosystem.Due to its technological limitation,the eddy covariance approach can only be applied within relatively small time and space scale,and it can only monitor the CO₂ flux,which fails to reflect and reveal multiple biochemical process like photosynthetic respiration decomposition and assimilation.However,modeling can expand the simulation context on the scale of time and space,and stimulate multiple biochemical process like carbon fixation and carbon release.The objective of the research is Hulunber temperate meadow steppe,with data taken from sample plot of typical meadow steppe with Stipa baicalensis as the main type and sample grazing plot in Hulunber National Field Ecosystem Research Station.The research will provide reference and evidence for further development of DNDC model,discussion of mechanism of carbon cycle in temperate meadow steppe ecosystem and to accurately predict future trend of climate change in temperate meadow steppe.The major achievement are as follows:1.By calibrating and validating DNDC model,the AGBC and NEE accumulation dynamic on Hulunber temperate meadow steppe has been reconstructed.Model efficiency is ranged from 0.89⁰.94 and 0.37⁰.53.Correlation coefficient is ranged from 0.97⁰.98 and 0.43⁰.68,which indicate that the DNDC model is effective on simulation ecosystem carbon cycle and carbon dynamics.2.DNDC model can simulate carbon exchange dynamic under fenced and grazing condition.According to model analysis,soil respiration accounts for 70.0⁷4.8%of the ecosystem respiration,and shoot respiration accounts for the rest 25.2%³0.0%.Root respiration accounts for 59.8%⁶6.7%of soil respiration,and soil heterotrophic respiration accounts for the rest 33.3⁴0.2%.There is a carbon exchange peak in the growing season,53.7%⁵7.0%of total carbon sequestration from photosynthesis and 76.5%⁸0.2%of total root respiration occurring in this period.3.Nine climate scenarios and two grassland managements are coupled to build the future climate change database,based on PRECIS climate prediction system HadCM3 models A1B scenario to simulate ecosystem change from 2016-2050.In the next 35 years precipitation and precipitation pattern are the key factor to temperate meadow steppe NPP,temperature has secondary influence on ecosystem NPP.Increase precipitation will cause higher NPP,decrease precipitation and dispersion in precipitation pattern will cause lower NPP.