黄淮海平原冬小麦夏玉米轮作系统碳收支量化分析

Quantifying Carbon Budget of Winter Wheat Summer Maize Rotation System in Huang-Huai-Hai Plain

摘要:

黄淮海平原是我国重要的农业基地,准确量化该地区农业生产的碳收支可为我国农业绿色发展和实现“ 双碳” 目标提供科学依据。 本研究基于 Biome-BGCMuSo 模型模拟了 1981—2100 年黄淮海平原冬小麦夏玉米轮作 (简称麦玉轮作)区域的初级生产力(GPP)、生态系统呼吸(RECO)和净生态系统生产力(NEP),并分析了其时空变化趋势。 结果表明:利用差分进化算法进行模型参数优化后,Biome BGCMuSo 模型可获得较高的模拟精度,日尺度 GPP、RECO、NEP 模拟值与观测值之间的决定系数(R )分别达到 0. 80、0. 64、0. 68,月尺度分别达到 0. 92、0. 73、 2 0. 83。 在时间尺度上, 在历史时段 (1981—2020 年), GPP、 RECO 和 NEP 的年均值分别为 1 682. 40、1 293. 12、 389. 28 gC / (m2·a),其中 GPP 和 RECO 显著增加,NEP 在 2000 年前显著增加之后变化不显著;在未来时段(2020— 2100 年)SSP245 情景下,GPP、RECO 和 NEP 的年均值分别为 2 015. 75、1 613. 06、402. 69 gC / (m2·a);SSP585 情景下 GPP、RECO 和 NEP 的年均值分别为 2 144. 67、1 729. 52、415. 15 gC / (m2·a)。 整体上,GPP 和 RECO 在未来时期呈现显著增加趋势,NEP 将先呈现相对稳定的变化趋势直至 2051 年后显著减小。 在空间尺度上,GPP 和 RECO 呈现出中部高而南北部低的空间分布格局,NEP 则从东南向西北方向递增。 气候变化背景下,黄淮海平原麦玉轮作系统未来时期碳汇功能减弱主要是由生态系统呼吸的增速超过作物初级生产力的增速所导致。

Abstract:

The Huang-Huai-Hai Plain is an important agricultural production base in China. Accurately quantifying the carbon budget in agricultural production could provide a scientific basis for the agriculture development in China. The Biome-BGCMuSo model was used to simulate the gross primary productivity (GPP), ecosystem respiration (RECO), and net ecosystem productivity (NEP)in the winter wheat summer maize rotation systems of the Huang Huai Hai Plain in period of 1981—2100, and their spatiotemporal change trends were analyzed as well. The results showed that after parameter optimization through the differential evolution algorithms, the simulation accuracy of the Biome BGCMuSo model was high. The determination coefficients (R2 )between the simulated and observed daily values of GPP, RECO, and NEP were 0. 80, 0. 64, and 0. 68, respectively. And the R2 values were 0. 92, 0. 73, and 0. 83 at monthly scale, respectively. In historical period of 1981—2020, the average annual values of GPP, RECO, and NEP were 1 682. 40 gC / (m2 ·a ), 1 293. 12 gC / (m2 ·a ), and 389. 28 gC / (m2·a), respectively. Among them, GPP and RECO were increased significantly, but NEP was increased significantly before 2000 and then changed insignificantly. In future period of 2020—2100, the average annual values of GPP, RECO, and NEP were 2 015. 75 gC / (m2·a), 1 613. 06 gC / (m2·a), and 402. 69 gC / (m2 · a )under the SSP245 scenario, while they were 2 144. 67 gC / (m2 · a ), 1 729. 52 gC / (m2·a), and 415. 15 gC / (m2·a)under the SSP585 scenario, respectively. GPP and RECO showed obvious increasing trends in the future, while NEP showed a relatively stable trend first and then decreased significantly after 2051. At spatial scale, GPP and RECO showed a distribution pattern of high in the middle and low in the northern and southern parts of the Huang-Huai-Hai Plain, while NEP was increased from southeast to northwest. Under future climate change, the weakening carbon sink function of the winter wheat summer maize rotation system will be mainly because the increasing rate of ecosystem respiration exceeded the increasing rate of crop gross primary productivity in the future. Since the quantification of agricultural carbon budget was of great significance for the ‘ carbon peak and carbon neutrality ’ goals and food security of China, more studies were needed to further quantify the carbon budget and explain the underlying change mechanism in the Huang-Huai-Hai Plain in the future.