生态系统呼吸
环境科学
生态系统
亚北极气候
草原
土壤呼吸
初级生产
全球变暖
氮气循环
土壤碳
自行车
碳循环
生态学
陆地生态系统
生产力
农学
气候变化
环境化学
大气科学
氮气
土壤水分
化学
生物
土壤科学
经济
有机化学
考古
宏观经济学
地质学
历史
作者
Kathiravan Meeran,Niel Verbrigghe,Johannes Ingrisch,Lucia Fuchslueger,Lena Müller,Páll Sigurðsson,Bjarni D. Sigurðsson,Herbert Wachter,Margarete Watzka,Jennifer L. Soong,Sara Vicca,Ivan A. Janssens,Michael Bahn
摘要
Abstract Climate warming has been suggested to impact high latitude grasslands severely, potentially causing considerable carbon (C) losses from soil. Warming can also stimulate nitrogen (N) turnover, but it is largely unclear whether and how altered N availability impacts belowground C dynamics. Even less is known about the individual and interactive effects of warming and N availability on the fate of recently photosynthesized C in soil. On a 10‐year geothermal warming gradient in Iceland, we studied the effects of soil warming and N addition on CO 2 fluxes and the fate of recently photosynthesized C through CO 2 flux measurements and a 13 CO 2 pulse‐labeling experiment. Under warming, ecosystem respiration exceeded maximum gross primary productivity, causing increased net CO 2 emissions. N addition treatments revealed that, surprisingly, the plants in the warmed soil were N limited, which constrained primary productivity and decreased recently assimilated C in shoots and roots. In soil, microbes were increasingly C limited under warming and increased microbial uptake of recent C. Soil respiration was increased by warming and was fueled by increased belowground inputs and turnover of recently photosynthesized C. Our findings suggest that a decade of warming seemed to have induced a N limitation in plants and a C limitation by soil microbes. This caused a decrease in net ecosystem CO 2 uptake and accelerated the respiratory release of photosynthesized C, which decreased the C sequestration potential of the grassland. Our study highlights the importance of belowground C allocation and C‐N interactions in the C dynamics of subarctic ecosystems in a warmer world.
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