基于CMIP6的中国北方草地生态系统年总初级生产力时空格局

Spatiotemporal Pattern of GPP of Grassland Ecosystem in Northern China Based on CMIP6

[目的]揭示我国北方草地年总初级生产力未来时空变化规律,为草地恢复及保护的政策制定提供重要依据。[方法]基于CMIP6中9个地球系统模式总初级生产力(Gross Primary Productivity,GPP)模拟数据,采用多模式集合平均(MME)的方法,在SSP1-2.6,SSP2-4.5,SSP3-7.0和SSP5-8.5未来情景下预估了21世纪我国北方草地生态系统AGPP的时空变化。[结果](1)多模式集合(MME)模拟的准确性和年度趋势相关系数达到0.83,较其他单个模式更准确。(2)1982—2100年,4个情景均得出我国北方草地AGPP整体呈现上升趋势,温室气体高排放情景下的上升趋势大于温室气体低排放情景下的上升趋势。(3)空间上,我国北方草地平均AGPP在历史及未来情景下均呈西北到东南递增的趋势,SSP1-2.6情景下AGPP年均值最低〔308.03 g C/(m^(2)·a)〕,SSP5-8.5情景下最高〔389.63 g C/(m^(2)·a)〕。(4)在4个未来情景下的不同草地类型中,温性草原AGPP年均值最高〔SSP1-2.6情景下为445.44 g C/(m^(2)·a),SSP2-4.5情景下为474.53 g C/(m^(2)·a),SSP3-7.0情景下为532.42 g C/(m^(2)·a),SSP5-8.5情景下为558.14 g C/(m^(2)·a)〕,稀疏灌丛最低〔SSP1-2.6情景下为128.51 g C/(m^(2)·a),SSP2-4.5情景下为141.31 g C/(m^(2)·a),SSP3-7.0情景下为155.38 g C/(m^(2)·a),SSP5-8.5情景下为167.29 g C/(m^(2)·a)〕。[结论]我国北方草地AGPP未来呈显著增长趋势,不同情景下AGPP的增长趋势各不相同,排放情景越高增长越显著,未来应加强对我国北方草地AGPP变化的研究。

[Objective]The aims of this study are to reveal the spatiotemporal variation of the annual gross primary productivity(AGPP)of grassland in northern China,and to provide an important basis for the policy formulation of grassland restoration and protection.[Methods]Based on the GPP simulation data of nine Earth system models in CMIP6,the traditional multi-model ensemble average(MME)was used to estimate the temporal and spatial changes of AGPP in grassland ecosystem of northern China in the 21st century under four future scenarios(SSP1-2.6,SSP2-4.5,SSP3-7.0 and SSP5-8.5).[Results](1)The accuracy and yearly trends of the MME simulation are more accurate than other individual patterns.(2)From 1982 to 2100,the AGPP in grasslands in northern China showed a fluctuating upward trend,and the upward trend under the high greenhouse gas emission scenario was greater than the upward trend under the low greenhouse gas emission scenario.(3)Spatially,the average AGPP of grassland in northern China showed an increasing trend from northwest to southeast under both historical and future scenarios,with the lowest annual average AGPP at 308.03 g C/(m^(2)·a)under SSP1-2.6 scenario and the highest at 389.63 g C/(m^(2)·a)under SSP5-8.5 scenario.(4)Among different grassland types in the four future scenarios,the annual mean value of AGPP in temperate grassland will be the highest〔445.44 g C/(m^(2)·a)in SSP1-2.6 scenario and 474.53 g C/(m^(2)·a)in SSP2-4.5 scenario〕.Under SSP3-7.0,it will be 532.42 g C/(m^(2)·a),under SSP5-8.5,it will be 558.14 g C/(m^(2)·a),and sparse shrub will be the lowest〔128.51 g C/(m^(2)·a)under SSP1-2.6〕.It will be 141.31 g C/(m^(2)·a)under SSP2-4.5,155.38 g C/(m^(2)·a)under SSP3-7.0,and 167.29 g C/(m^(2)·a)under SSP5-8.5.[Conclusion]The AGPP in grassland in northern China will show a significant growth trend in the future,and the change trend will increase with the increase of radiation intensity and CO 2 emissions.The growth trend of AGPP under different scenarios is different,and the higher the emission scenario,the more significant the growth.Future research on AGPP change of grassland in northern China should be strengthened.