State Key Laboratory of Estuarine and Coastal Research, Shanghai Key Lab for Urban Ecological Processes and Eco-Restoration, School of Ecological and Environmental Sciences, East China Normal University, Shanghai, 200000, China.
Joint Translational Science and Technology Research Institute, East China Normal University and Haifa University, Shanghai, 200000, China.
Ecology. 2021 Feb;102(2):e03236. doi: 10.1002/ecy.3236. Epub 2020 Nov 30.
Coastal wetlands have the highest carbon sequestration rate per unit area among all unmanaged natural ecosystems. However, how the magnitude and seasonality of the CO sink in coastal wetlands will respond to future climate warming remains unclear. Here, based on measurements of ecosystem CO fluxes in a field experiment in the Yellow River Delta, we found that experimental warming (i.e., a 2.4°C increase in soil temperature) reduced net ecosystem productivity (NEP) by 23.7% across two growing seasons of 2017-2018. Such a reduction in NEP resulted from the greater decrease in gross primary productivity (GPP) than ecosystem respiration (ER) under warming. The negative warming effect on NEP mainly occurred in summer (-43.9%) but not in autumn (+61.3%), leading to a shifted NEP seasonality under warming. Further analyses showed that the warming effects on ecosystem CO exchange were mainly controlled by soil salinity and its corresponding impacts on species composition. For example, warming increased soil salinity (+35.0%), reduced total aboveground biomass (-9.9%), and benefited the growth of plant species with high salt tolerance and late peak growth. To the best of our knowledge, this study provides the first experimental evidence on the reduced magnitude and shifted seasonality of CO exchange under climate warming in coastal wetlands. These findings underscore the high vulnerability of wetland CO sink in coastal regions under future climate change.
滨海湿地在所有未管理的自然生态系统中具有最高的单位面积碳固存率。然而，滨海湿地 CO2 汇的幅度和季节性将如何应对未来气候变暖仍不清楚。在这里，我们基于黄河三角洲野外实验中生态系统 CO2 通量的测量结果，发现实验性增温（即土壤温度升高 2.4°C）导致 2017-2018 年两个生长季的净生态系统生产力（NEP）降低了 23.7%。在增温条件下，NEP 的减少主要是由于总初级生产力（GPP）的下降幅度大于生态系统呼吸（ER）。增温对 NEP 的负向影响主要发生在夏季（-43.9%），而不是秋季（+61.3%），导致增温下 NEP 的季节性发生转移。进一步的分析表明，生态系统 CO2 交换的增温效应主要受土壤盐分及其对物种组成的相应影响控制。例如，增温增加了土壤盐分（+35.0%），降低了地上总生物量（-9.9%），并有利于具有高耐盐性和晚峰值生长的植物物种的生长。据我们所知，这项研究提供了关于滨海湿地在气候变暖下 CO2 交换幅度降低和季节性转移的第一个实验证据。这些发现突显了未来气候变化下滨海地区湿地 CO2 汇的高度脆弱性。
