Biophysical drivers of net ecosystem and methane exchange across phenological phases in a tidal salt marsh
Biophysical drivers of net ecosystem and methane exchange across phenological phases in a tidal salt marsh
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DOI：
10.1016/j.agrformet.2020.108309
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发表时间：
2021-04
影响因子：
6.2
通讯作者：
A. Vázquez‐Lule;R. Vargas
中科院分区：
文献类型：
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作者：
A. Vázquez‐Lule;R. Vargas
盐沼是蓝碳生态系统的一部分，是大型的碳库。不幸的是，关于盐沼和大气之间的净生态系统（NEE）和甲烷（CH 4）交换的信息有限，无法充分了解其碳动力学。我们通过植物物候期（即，Greenup，Maturity，Senescence and Dormancy）对NEE和CH 4交换的影响。我们使用了三年的数据来自涡度协方差，PhenoCam（测量植被物候），辅助气象和水/土壤变量。总的来说，NEE在各物候期间差异显著（p < 0.05），而CH 4交换在除返青期和休眠期外的各物候期间差异显著（p <0.05）。整个成熟期的CO2净吸收量较高（-61 g C-CO2 m2），而休眠期的CO2排放量较高（182 g C-CO2 m2）。休眠期的CO2排放量较低，但稳定，超过了生长期的CO2吸收量，占该生态系统CO2年排放量的72%以上。在成熟期（3.7克C-CH 4 m2）和衰老期（4.2克C-CH 4 m2），CH 4净排放量较高。光合有效辐射（PAR）显著影响（r2> 0. 57）各物候期的日间NEE，但地下水位（WTL）、水温和气压等变量的组合对CH 4交换的解释是相关的。该研究场地是大气的总净碳源，年排放量为13-201 g C-CO2 m − 2 yr − 1和8.5-15.2 g C-CH 4 m − 2 yr −1。我们的研究结果提供了以下方面的见解：a）植物物候期对生态系统尺度CO2和CH 4通量的作用; B）模拟盐沼生态系统尺度CO2和CH 4通量的挑战;以及c）在这些生态系统中进行碳管理和核算时应考虑的潜在大气碳净损失。
Salt marshes are large carbon reservoirs as part of blue carbon ecosystems. Unfortunately, there is limited information about the net ecosystem (NEE) and methane (CH4) exchange between salt marshes and the atmosphere to fully understand their carbon dynamics. We tested the influence of biophysical drivers by plant phenological phases (i.e., Greenup, Maturity, Senescence and Dormancy) on NEE and CH4exchange in a grass-dominated temperate tidal salt marsh. We used three years of data derived from eddy covariance, PhenoCam (to measure vegetation phenology), and ancillary meteorological and water/soil variables. Overall, NEE showed significant differences among all phenological phases (p < 0.05), while CH4exchange had significant differences among all phases except for Greenup and Dormancy. Net CO2uptake was higher across Maturity (-61 g C-CO2m2), while CO2emissions were higher during Dormancy (182 g C-CO2m2). The lower but constant CO2emissions during Dormancy overshadowed the CO2uptake during the growing season and contributed to >72% of the annual CO2emissions in this ecosystem. Net CH4emissions were higher during Maturity (3.7 g C-CH4m2) and Senescence (4.2 g C-CH4m2). Photosynthetically active radiation (PAR) substantially influenced (r2> 0.57) daytime NEE across phenological phases, but a combination of variables including water table level (WTL), water temperature and atmospheric pressure were relevant to explain CH4exchange. The study site was an overall net carbon source to the atmosphere with annual emissions of 13-201 g C-CO2m−2yr−1and 8.5-15.2 g C-CH4m−2yr−1. Our findings provide insights on: a) the role of plant phenological phases on ecosystem-scale CO2and CH4fluxes; b) challenges for modeling ecosystem-scale CO2and CH4fluxes in salt marshes; and c) the potential net loss of carbon to the atmosphere that should be considered for carbon management and accounting in these ecosystems.