中国陆地生态系统增汇潜力研究展望

碳达峰与碳中和已经成为全球气候治理和生态文明建设的重大需求.厘清陆地生态系统增汇潜力不仅对准确预估未来气候变化对陆地生态系统的影响至关重要,更是人类制定气候变化应对方案的基本前提.本文从陆地生态系统碳储量和碳汇视角,综述了中国森林、灌丛、草原、农田和湿地等主要陆地生态系统碳储量、中国陆地生态系统碳汇及其对不同气候变化情景和人类活动的响应,发现中国陆地生态系统碳储量和碳汇的评价结果因不同的研究方法和资料差异较大,需要不断完善陆地生态系统碳储量和碳汇的评估方法并基于最新资料不断更新评估结果.文章进一步指出,现有研究对未来不同时期、不同排放情景下中国陆地生态系统的碳汇功能,尤其是同一区域不同国家重大生态工程增汇潜力的整合研究仍不足,对氮沉降及其与气候变化、大气CO_(2)浓度变化协同作用的影响,特别是对国家重大生态工程增汇潜力影响的研究仍不够,还没有开展中国陆地生态系统增汇的气候变化风险研究.据此,本文指出,未来中国陆地生态系统增汇研究需要重视国家重大生态工程增汇潜力及其风险评价,重点关注高度空间异质性的区域陆地生态系统碳收支模拟技术和不同气候变化情景下气象资料获取技术的发展,为中国陆地生态系统增汇的系统管理优化方案提供科学支撑,服务于国家碳中和战略.

Climatic suitability and spatial distribution for summer maize cultivation in China at 1.5 and 2.0 °C global warming

Evaluating climatic suitability of crop cultivation lays a foundation for agriculture coping with climate change scientifically. Herein, we analyse changes in the climatically suitable distribution of summer maize cultivation in China at 1.5℃(GW1.5) and 2.0℃(GW2.0) global warming in the future according to the temperature control targets set by the Paris Agreement. Compared with the reference period (1971- 2000), the summer maize cultivation climatically suitable region (CSR) in China mainly shifts eastwards, and its acreage significantly decreases at both GW1.5 and GW2.0. Despite no dramatic changes in the CSR spatial pattern, there are considerable decreases in the acreages of optimum and suitable regions (the core of the main producing region), indicating that half-a-degree more global warming is unfavourable for summer maize production in China's main producing region. When the global warming threshold increases from GW1.5 to GW2.0, the centres-of-gravity of optimum areas shift northeastward under RCP4.5 and RCP8.5, the centres-of-gravity of both suitable and less suitable areas shift northwestward, though the northward trend is more prominent for the less suitable areas, and the centre-of-gravity of unsuitable areas shifts southeastward. Generally, half-a-degree more global warming drives the cultivable areas of summer maize to shift northward in China, while the west region shows a certain potential for expansion of summer maize cultivation.

Projection of Heat Injury to Single-Cropping Rice in the Middle and Lower Reaches of the Yangtze River, China under Future Global Warming Scenarios

Based on simulation results from the 16 CMIP5 model runs under three Representative Concentration Pathways(RCP2.6, RCP4.5, and RCP8.5) in combination with the recent five years of growth-stage data from agrometeorological observation stations in the middle and lower reaches of the Yangtze River, changes in heat injury and spatial distribution patterns of single-cropping rice in China during the early(2016–35), middle(2046–65), and late(2080–99) 21 st century were projected by using quantitative estimations. Relative to the reference period(1986–2005), the occurrence probabilities of heat injury to single-cropping rice under different RCP scenarios increased significantly, showing a trend of mild > moderate > severe. The occurrence probabilities increased with time and predicted emissions, especially the average and maximum occurrence probabilities, which were ～48% and ～80%,respectively, in the late 21 st century under the RCP8.5 scenario. The spatial patterns of the occurrence probabilities at each level of heat injury to single-cropping rice did not change, remaining high in the middle planting region and low in the east. The high-value areas were mainly in central Anhui and southeastern Hubei provinces, and the areas extended to the northwest and northeast of the cultivation area over time. Under the RCP2.6, RCP4.5, and RCP8.5 scenarios, the total area of heat injury to single-cropping rice showed a significant linear increasing trend of 7.4 × 10~3, 19.9× 10~3, and 35.3 × 10~3 ha yr^(–1), respectively, from 2016 to 2099, and the areas of heat injury were greatest in the late21 st century, accounting for ～25%, ～40%, and ～59% of the cultivation area.

A New Prediction Model for Grain Yield in Northeast China Based on Spring North Atlantic Oscillation and Late-Winter Bering Sea Ice Cover

Accurate estimations of grain output in the agriculturally important region of Northeast China are of great strategic significance for guaranteeing food security.New prediction models for maize and rice yields are built in this paper based on the spring North Atlantic Oscillation index and the Bering Sea ice cover index.The year-to-year increment is first forecasted and then the original yield value is obtained by adding the historical yield of the previous year.The multivariate linear prediction model of maize shows good predictive ability,with a low normalized root-mean-square error（NRMSE）of 13.9%,and the simulated yield accounts for 81%of the total variance of the observation.To improve the performance of the multivariate linear model,a combined forecasting model of rice is built by considering the weight of the predictors.The NRMSE of the model is 12.9%and the predicted rice yield explains 71%of the total variance.The corresponding cross-validation test and independent samples test further demonstrate the efficiency of the models.It is inferred that the statistical models established here by applying year-to-year increment approach could make rational prediction for the maize and rice yield in Northeast China before harvest.The present study may shed new light on yield prediction in advance by use of antecedent large-scale climate signals adequately.