Peatlands and their carbon dynamics in northern high latitudes from 1990 to 2300: a process-based biogeochemistry model analysis
Peatlands and their carbon dynamics in northern high latitudes from 1990 to 2300: a process-based biogeochemistry model analysis
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DOI：
10.5194/bg-20-251-2023
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发表时间：
2023-01
期刊：
影响因子：
4.9
通讯作者：
Bailu Zhao;Q. Zhuang
中科院分区：
文献类型：
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作者：
Bailu Zhao;Q. Zhuang
摘要。在全新世期间，北部泥炭地一直是一个巨大的碳汇，但在未来的气候变化下，它们是否会继续成为碳汇还不确定。本研究利用泥炭地版陆地生态系统模型（PTEM）模拟了到2300年北方泥炭地对未来气候的响应。模拟采用两组CMIP5气候数据（IPSL-CM5A-LR和bcc-csm1-1）在3种变暖情景（rcp为2.6、4.5和8.5）下进行。模拟了泥炭地面积的扩张、收缩和碳的积累与分解。在21世纪，除bcc-csm1-1的RCP 2.6（一个0.8 Pg C的汇）外，北方泥炭地预计在所有气候情景下都是1.2-13.3 Pg C的碳源。2100 ~ 2300年，所有情景下的北部泥炭地都是IPSL-CM5A-LR情景下的碳源，比bcc-csm1-1情景的碳源更大（5.9 ~ 118.3 Pg C比0.7 ~ 87.6 Pg C）。碳源主要来源于：(1)泥炭地地下水位变深和冻土融化加速分解速率；(2)随着气候变暖，净初级生产量（NPP）的增加幅度不大，因为泥炭干燥抑制了净氮矿化；(3)随着WTD的加深，泥炭地由苔藓-草本为主向苔藓-木本为主转变，木本植物对氮的需要量增加。在ipsl - cm3a - lr情景下，在泛北极年气温达到−2.6至−2.89°C之前，北部泥炭地仍然是一个碳汇，而在bc -csm1-1情景下，这个阈值是−2.09至−2.35°C。该研究预测，北部泥炭地将在2050年左右发生汇源转移，比之前估计的2100年之后的时间要早，并强调了北部泥炭地对气候变化的脆弱性。
Abstract. Northern peatlands have been a large C sink during the Holocene, but whether they will keep being a C sink under future climate change is uncertain. This study simulates the responses of northern peatlands to future climate until 2300 with a Peatland version Terrestrial Ecosystem Model (PTEM). The simulations are driven with two sets of CMIP5 climate data (IPSL-CM5A-LR and bcc-csm1-1) under three warming scenarios (RCPs 2.6, 4.5 and 8.5). Peatland area expansion, shrinkage, and C accumulation and decomposition are modeled. In the 21st century, northern peatlands are projected to be a C source of 1.2–13.3 Pg C under all climate scenarios except for RCP 2.6 of bcc-csm1-1 (a sink of 0.8 Pg C). During 2100–2300, northern peatlands under all scenarios are a C source under IPSL-CM5A-LR scenarios, being larger sources than bcc-csm1-1 scenarios (5.9–118.3 vs. 0.7–87.6 Pg C). C sources are attributed to (1) the peatland water table depth (WTD) becoming deeper and permafrost thaw increasing decomposition rate; (2) net primary production (NPP) not increasing much as climate warms because peat drying suppresses net N mineralization; and (3) as WTD deepens, peatlands switching from moss–herbaceous dominated to moss–woody dominated, while woody plants require more N for productivity. Under IPSL-CM5A-LR scenarios, northern peatlands remain as a C sink until the pan-Arctic annual temperature reaches −2.6 to −2.89 ∘C, while this threshold is −2.09 to −2.35 ∘C under bcc-csm1-1 scenarios. This study predicts a northern peatland sink-to-source shift in around 2050, earlier than previous estimates of after 2100, and emphasizes the vulnerability of northern peatlands to climate change.