Snow melt stimulates ecosystem respiration in Arctic ecosystems
Snow melt stimulates ecosystem respiration in Arctic ecosystems
复制标题
雪融化刺激北极生态系统的生态系统呼吸
DOI：
10.1111/gcb.15193
复制
发表时间：
2020-06-30
影响因子：
11.6
通讯作者：
Zona, Donatella
中科院分区：
文献类型：
--
作者：
Arndt, Kyle A.;Lipson, David A.;Zona, Donatella
北极生态系统的寒冷季节对这些脆弱生态系统的年度碳平衡越来越重要。北极的冬天很大程度上是严酷的，无法进入，导致这段时间的历史数据空白。直到最近，人们一直认为寒冷季节对年度碳平衡的影响可以忽略不计，但随着数据覆盖范围的增加和北极变暖，寒冷季节已被证明占年度甲烷（CH4）排放量的一半以上，并可以抵消夏季光合作用二氧化碳（CO2）的吸收。冻融循环动力学在控制冷季CO（2）和CH（4）损失方面起着关键作用，但其关系尚未得到广泛研究。在这里，我们分析冻融过程中，通过在原位CO（2）和CH（4）通量结合土壤芯的物理结构和孔隙水样品的氧化还原地球化学。我们发现，在土壤核心的冻结前的水的运动，在土壤中留下空气空间，这使得快速渗透的富氧的雪融化在春天所示的孔隙水中的氧化铁。融雪期与生态系统呼吸上升相吻合，可以抵消高达41%的夏季CO（2）吸收。我们的研究强调了这一重要的季节性过程，并表明春季温室气体排放主要是由于呼吸产生的，而不仅仅是储存气体的爆发。预计进一步变暖将导致积雪增加和更深的融化，这可能会增加这种生态系统呼吸主导的融雪期，造成春季更大的温室气体损失。
Cold seasons in Arctic ecosystems are increasingly important to the annual carbon balance of these vulnerable ecosystems. Arctic winters are largely harsh and inaccessible leading historic data gaps during that time. Until recently, cold seasons have been assumed to have negligible impacts on the annual carbon balance but as data coverage increases and the Arctic warms, the cold season has been shown to account for over half of annual methane (CH4) emissions and can offset summer photosynthetic carbon dioxide (CO2) uptake. Freeze-thaw cycle dynamics play a critical role in controlling cold season CO(2)and CH(4)loss, but the relationship has not been extensively studied. Here, we analyze freeze-thaw processes through in situ CO(2)and CH(4)fluxes in conjunction with soil cores for physical structure and porewater samples for redox biogeochemistry. We find a movement of water toward freezing fronts in soil cores, leaving air spaces in soils, which allows for rapid infiltration of oxygen-rich snow melt in spring as shown by oxidized iron in porewater. The snow melt period coincides with rising ecosystem respiration and can offset up to 41% of the summer CO(2)uptake. Our study highlights this important seasonal process and shows spring greenhouse gas emissions are largely due to production from respiration instead of only bursts of stored gases. Further warming is projected to result in increases of snowpack and deeper thaws, which could increase this ecosystem respiration dominate snow melt period causing larger greenhouse gas losses during spring.