State Key Laboratory of Numerical Modeling for Atmospheric Sciences and Geophysical Fluid Dynamics, Institute of Atmospheric Physics, Chinese Academy of Sciences, Beijing, China.
State Key Laboratory of Atmospheric Boundary Layer Physics and Atmospheric Chemistry, Institute of Atmospheric Physics, Chinese Academy of Sciences, Beijing, China.
PLoS One. 2019 Jul 22;14(7):e0215261. doi: 10.1371/journal.pone.0215261. eCollection 2019.
The Tibetan Plateau is an important component of the global carbon cycle due to the large permafrost carbon pool and its vulnerability to climate warming. The Tibetan Plateau has experienced a noticeable warming over the past few decades and is projected to continue warming in the future. However, the direction and magnitude of carbon fluxes responses to climate change and elevated CO2 concentration under Representative Concentration Pathways (RCP) scenarios in the Tibetan Plateau grassland are poorly known. Here, we used a calibrated and validated biogeochemistry model, CENTURY, to quantify the contributions of climate change and elevated CO2 on the future carbon budget in the alpine grassland under three RCP scenarios. Though the Tibetan Plateau grassland was projected a net carbon sink of 16 ~ 25 Tg C yr-1 in the 21st century, the capacity of carbon sequestration was predicted to decrease gradually because climate-driven increases in heterotrophic respiration (Rh) (with linear slopes 0.49 ~ 1.62 g C m-2 yr-1) was greater than the net primary production (NPP) (0.35 ~ 1.52 g C m-2 yr-1). However, the elevated CO2 contributed more to plant growth (1.9% ~ 7.3%) than decomposition (1.7% ~ 6.1%), which could offset the warming-induced carbon loss. The interannual and decadal-scale dynamics of the carbon fluxes in the alpine grassland were primarily controlled by temperature, while the role of precipitation became increasingly important in modulating carbon cycle. The strengthened correlation between precipitation and carbon budget suggested that further research should consider the performance of precipitation in evaluating carbon dynamics in a warmer climate scenario.
青藏高原是全球碳循环的重要组成部分，这主要是因为其拥有大量的永久冻土碳库，并且这些碳库对气候变暖十分敏感。在过去几十年中，青藏高原经历了显著的升温，预计未来还将继续升温。然而，在代表性浓度路径（RCP）情景下，青藏高原草原对气候变化和升高的 CO2 浓度的碳通量响应的方向和幅度尚不清楚。在这里，我们使用了经过校准和验证的生物地球化学模型 CENTURY，来量化气候变化和升高的 CO2 对青藏高原高寒草原未来碳预算的贡献。尽管预计到 21 世纪，青藏高原草原将成为一个净碳汇，碳汇量为 16 到 25 太吨碳/年，但由于气候驱动的异养呼吸（Rh）增加（线性斜率为 0.49 到 1.62 克碳/平方米/年）大于净初级生产力（NPP）（0.35 到 1.52 克碳/平方米/年），碳固存能力预计将逐渐下降。然而，升高的 CO2 对植物生长的贡献（1.9%到 7.3%）大于分解作用（1.7%到 6.1%），这可以抵消变暖引起的碳损失。高寒草原碳通量的年际和年代际动态主要受温度控制，而降水在调节碳循环方面的作用变得越来越重要。降水与碳预算之间的相关性增强表明，在评估更温暖气候情景下的碳动态时，应进一步考虑降水的表现。
