Division of Terrestrial Ecosystem Research, Department of Microbiology and Ecosystem Science, Center of Microbiology and Environmental Systems Science, University of Vienna, Vienna, Austria.
Doctoral School in Microbiology and Environmental Science, University of Vienna, Vienna, Austria.
Glob Chang Biol. 2024 Jun;30(6):e17379. doi: 10.1111/gcb.17379.
Microbial necromass carbon (MNC) accounts for a large fraction of soil organic carbon (SOC) in terrestrial ecosystems. Yet our understanding of the fate of this large carbon pool under long-term warming is uncertain. Here, we show that 14 years of soil warming (+4°C) in a temperate forest resulted in a reduction in MNC by 11% (0-10 cm) and 33% (10-20 cm). Warming caused a decrease in the content of MNC due to a decline in microbial biomass carbon and reduced microbial carbon use efficiency. This reduction was primarily caused by warming-induced limitations in available soil phosphorus, which, in turn, constrained the production of microbial biomass. Conversely, warming increased the activity of soil extracellular enzymes, specifically N-acetylglucosaminidase and leucine aminopeptidase, which accelerated the decomposition of MNC. These findings collectively demonstrate that decoupling of MNC formation and decomposition underlie the observed MNC loss under climate warming, which could affect SOC content in temperate forest ecosystems more widespread.
微生物残体碳（MNC）在陆地生态系统中占土壤有机碳（SOC）的很大一部分。然而，我们对长期变暖下这个巨大碳库的命运的理解还不确定。在这里，我们表明，在温带森林中进行了 14 年的土壤增温（+4°C），导致 MNC 在 0-10cm 土层中减少了 11%，在 10-20cm 土层中减少了 33%。增温导致 MNC 含量下降，这是由于微生物生物量碳减少和微生物碳利用效率降低所致。这种减少主要是由于变暖引起的土壤有效磷的限制，这反过来又限制了微生物生物量的产生。相反，增温增加了土壤胞外酶的活性，特别是 N-乙酰氨基葡萄糖苷酶和亮氨酸氨基肽酶，这加速了 MNC 的分解。这些发现共同表明，在气候变暖下，MNC 形成和分解的解耦是导致观察到的 MNC 损失的原因，这可能会影响更广泛的温带森林生态系统中的 SOC 含量。
