Reduced methane emissions in former permafrost soils driven by vegetation and microbial changes following drainage.
Reduced methane emissions in former permafrost soils driven by vegetation and microbial changes following drainage.
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DOI：
10.1111/gcb.16137
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发表时间：
2022-05
影响因子：
11.6
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中科院分区：
文献类型：
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在北极地区，预计到2100年，融化的永久冻土将释放5000万至250亿吨碳。这些数据主要来自富含碳的湿地，尽管71%的碳库储存在融化速度较快的矿物土壤中，那里靠近永久冻土区外部边界的生态系统尤其脆弱。虽然目前的融化地点和短期融化实验有大量的数据，但对最终解冻和共生排水后的长期变化的调查很少。在这里，我们展示了两个具有不同永久冻土融化历史的可比草袜冻土带的生态系统变化，代表了15年和25年的自然排水，导致甲烷排放量减少了10倍(3.2%±22.2vs.0.3%±0.4%mg C-CH4−2天−1)，而二氧化碳排放量是相似的。这些数据扩展了基于短期试验性排水的早期研究的时间视角。总体微生物群落结构在不同地点之间没有显著差异，尽管最高级地点的表层土壤较干燥，导致表层甲烷菌及其合养伙伴的丧失，而甲烷氧化菌的丰度保持不变。由此产生的更深的曝气区可能会增加CH4的氧化，因为CH4在氧化区的停留时间更长，而观察到的通风组织植物的损失减少了CH4从更深的土壤层直接向大气的扩散。我们的研究结果强调了在研究气候变化对CH4排放的长期影响时包括水文、植被和微生物特定反应的重要性，并强调了需要来自不同土壤类型和融化历史的数据。多年冻土后的变化减少了旱地矿物土壤的甲烷排放。在这里，我们展示了两个草袜冻土带的生态系统变化，它们具有不同的永久冻土融化历史，导致CH4排放减少了10倍。随着时间的推移，水文的变化降低了表层土壤中的水分饱和度，导致了不利于产甲烷的条件。较深的曝气区可能由于较长的停留时间而增加了CH4的氧化，而观察到的通风组织植物的损失减少了CH4从更深的土壤中扩散。我们的发现强调了在研究长期冻土融化对潜在CH4排放的影响时，包括水文、植被和微生物反应的重要性。
In Arctic regions, thawing permafrost soils are projected to release 50 to 250 Gt of carbon by 2100. This data is mostly derived from carbon‐rich wetlands, although 71% of this carbon pool is stored in faster‐thawing mineral soils, where ecosystems close to the outer boundaries of permafrost regions are especially vulnerable. Although extensive data exists from currently thawing sites and short‐term thawing experiments, investigations of the long‐term changes following final thaw and co‐occurring drainage are scarce. Here we show ecosystem changes at two comparable tussock tundra sites with distinct permafrost thaw histories, representing 15 and 25 years of natural drainage, that resulted in a 10‐fold decrease in CH4 emissions (3.2 ± 2.2 vs. 0.3 ± 0.4 mg C‐CH4 m−2 day−1), while CO2 emissions were comparable. These data extend the time perspective from earlier studies based on short‐term experimental drainage. The overall microbial community structures did not differ significantly between sites, although the drier top soils at the most advanced site led to a loss of methanogens and their syntrophic partners in surface layers while the abundance of methanotrophs remained unchanged. The resulting deeper aeration zones likely increased CH4 oxidation due to the longer residence time of CH4 in the oxidation zone, while the observed loss of aerenchyma plants reduced CH4 diffusion from deeper soil layers directly to the atmosphere. Our findings highlight the importance of including hydrological, vegetation and microbial specific responses when studying long‐term effects of climate change on CH4 emissions and underscores the need for data from different soil types and thaw histories. Post‐permafrost changes reduced methane emission from upland mineral soils. Here we show ecosystem changes at two tussock tundra sites with distinct permafrost thaw histories, leading to a 10‐fold decrease in CH4 emissions. With progressing time, changes in hydrology reduced water saturation in the topsoil, leading to unfavorable conditions for methanogenesis. Deeper aeration zones likely increased CH4 oxidation due to longer residence time in the oxidation zone, while the observed loss of aerenchyma plants reduced CH4 diffusion from deeper soil. Our findings highlights the importance of including hydrological, vegetation and microbial responses when studying long‐term permafrost‐thaw effects on potential CH4 emissions.
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