我国南方不同类型草地生产力及对气候变化的响应

PRODUCTIVITY OF DIFFERENT TYPES OF GRASSLAND PLOTS AND THEIR RESPONSES TO CLIMATE CHANGE IN THE SOUTHERN CHINA

为进一步明晰南方不同类型草地的碳源汇关系,预测未来气候情景下可能的碳循环特征,利用本地参数化的BIOME-BGC模型对2001-2010年低山丘陵草原化草甸、典型草山草坡和典型山地草甸样地净初级生产力（NPP）与净生态系统生产力（NEP）进行了模拟估算。不同类型草地的NPP和NEP 10年间变化趋势不同,低山丘陵草原化草甸、典型草山草坡和典型山地草甸的NPP平均值分别为357.17、232.4和191.96gC/（m2·a）;NEP的平均值分别为3.25、21.28和81.96gC/（m2·a）。3种类型草地NPP与温度之间存在显著的正相关关系,NEP与温度之间存在着显著的负相关关系;本模型模拟的NPP和NEP与年平均降水量之间相关性不明显。未来气候情景C1P-1T1下（CO2浓度倍增,年均温增加2℃,降水减少10%）,低山丘陵草原化草甸样地NPP增加26.93%,NEP增加160%;典型草山草坡样地NPP增加62.20%,NEP增加153%;典型山地草甸样地NPP增加135%,NEP增加206%。3种南方草地类型在未来气候情景下都将有一定的碳汇增长潜力,其中以典型山地草甸的碳汇潜力最为明显,与降水量相比受温度变化的影响相对较大。

Grassland ecosystems play important roles in the global carbon cycle.The net primary productivity（NPP）and net ecosystem productivity（NEP）of grassland ecosystems have become the hot spots in the researches on terrestrial ecosystems.The BIOME-BGC model is a biogeochemical cycle model,which simulates the storage and fluxes of water,carbon and nitrogen within the vegetation,litter and soil components of a terrestrial ecosystem.In this paper,the BIOME-BGC model was parameterized repeatedly and used to estimate the NPP and NEP of typical grasslands in the southern China from 2001 to 2010.It was shown that the mean NPP and NEP of temperate moist meadow in Chuzhou of Anhui Province were 357.17 and 3.25 g C m-2 yr-1respectively,and those of typical grassland mountain and slope in Weining of Guizhou Province were 232.40 and 21.28 g C m-2 yr-1,and those of typical alpine meadow in Hongyuan of Sichuan Province were 191.96 and 81.96 g C m-2 yr-1respectively.It was proved by correlation analysis that the significant positive correlation existed between the NPP of the three typical grasslands and annual mean temperature,and the negative correlation was found between the NEP of the three typical grasslands in the southern China and annual mean temperature.However,the correlation between precipitation and productivity index（NPP,NEP）was not evident.The tendency of NPP and NEP were predicted by using BIOME-BGC model under future climate change scenarios,which were designed according to the two research reports proposed by Intergovernmental Panel on Climate Change（IPCC）,namely annual mean temperature increasing 2degree centigrade,remaining unchanged and decreasing 2degree centigrade,CO2 doubling and keeping unchanged,annual precipitation increasing by 10%,decreasing by 10% and remaining unchanged.The results was shown that under C1P-1T1 scenario（CO2doubling,annual precipitation decreased by 10%,annual mean temperature increased by 2degree centigrade）which might be the most probable climate pattern,the NPP and NEP of temperate moist meadow increased by 26.93% and 160%,and those of typical grassland mountain and slope increased by 62.20%and 153%respectively,and those of typical alpine meadow increased by135% and 206%respectively.The relationship between carbon source and sink of different types of grasslands was distinct,and the features of carbon cycle under future climate change scenarios were predicted in this research.It just fills up the vacancy of relative research on carbon cycling and carbon storage of grasslands ecosystem in the southern China,and provides the reliable bases for the database of carbon sink.However,certain deviations were also observed in this study,which need to be investigated in future research.Besides,the parameterized scheme for the model may bring about some uncertainty for estimating NPP and NEP of grasslands.So the parameters of the model need to be set and modified according to the biological traits of grasslands in the southern China.In addition,some possible factors such as the invisibility of underground at a larger spatial scale,soil texture,moisture and fertility,interspecific competition in a community may be related with the uncertainty of the model.