耦合模型比对项目
环境科学
碳汇
水槽(地理)
大气科学
湿地
生态系统
纬度
每年落叶的
碳循环
气候变化
碳纤维
焊剂(冶金)
气候学
气候模式
生态学
化学
物理
数学
生物
地理
地图学
有机化学
算法
天文
地质学
复合数
作者
Congsheng Fu,Guiling Wang,Yuting Yang,Huawu Wu,Haohao Wu,Haixia Zhang,Ye Xia
摘要
Abstract The response of net ecosystem exchange (NEE) to environmental changes is strongly nonlinear, characterized with threshold behaviors that are not well understood. Here, we investigated the threshold behaviors in the relationship between NEE and surface air temperature based on FLUXNET2015 observations, Community Land Model simulations, and Coupled Model Intercomparison Project Phase 6 (CMIP6) model outputs. An air temperature threshold of 16.4°C, corresponding to the maximum carbon sink ( T sink ), was identified for all 205 FLUXNET2015 sites combined. For deciduous broadleaf and mixed forests, wetlands and wheat‐barley croplands, and rice‐maize‐soybean croplands, we identified a carbon‐source threshold ( T source ) of 6.8, 5.0, and 18.0°C, respectively, beyond which the ecosystem becomes less of a carbon source. Five cold climate types mainly encompassing these plant functional types showed a clear carbon‐source T source of 12.2°C. Six CMIP6 models project a threshold temperature increase of 1.0–2.8°C by the 2090s, which results primarily from a shift of the optimum temperature for gross primary production. Not accounting for the warming‐induced threshold changes may lead to an estimated time of the average summer air temperature passing T sink that is earlier by 4.5–6.7 and 6.4–12.2 years at low (15°N–15°S) and high (≥60°S or ≥ 60°N) latitudes, respectively.
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