The response of the Dajiuhu Peatland ecosystem to hydrological variations: Implications for carbon sequestration and peatlands conservation
The response of the Dajiuhu Peatland ecosystem to hydrological variations: Implications for carbon sequestration and peatlands conservation
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DOI：
10.1016/j.jhydrol.2022.128307
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发表时间：
2022-08
影响因子：
6.4
通讯作者：
Hongye Liu;Yansheng Gu;Jiwen Ge;Zicheng Yu;Xiangnan Xu;Zhiqi Zhang;Shenggao Cheng;S. Xie
中科院分区：
文献类型：
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作者：
Hongye Liu;Yansheng Gu;Jiwen Ge;Zicheng Yu;Xiangnan Xu;Zhiqi Zhang;Shenggao Cheng;S. Xie
泥炭地是最大的生物圈碳库之一，正面临着气候变化导致的地下水位下降和碳损失。为了对全球变化背景下的泥炭地保护和碳水循环提供见解，应该考虑泥炭地生态与地下水位深度(WTD)之间的详细关系。本研究以大九湖泥炭地碳通量为研究对象，综合了湿地日变化、碳动态、植被和微生物活动等方面的数据，以期更好地了解生态环境对水文变化的响应。根据现代监测，随着WTD的下降，日CH4排放量减少，而CO2排放量增加。当WTD大于30 cm时，根据非线性模型，日固碳量减少，直至接近0。通过与以往的土壤TOC、植被和微生物空间调查的比较，我们提出了大约30 cm是影响泥炭地生态系统结构和功能的临界WTD水平(转折点或区域)。长期和严重的干旱可能会引发泥炭地的生态转变，因为氧气可获得性的增加和水可获得性的减少不能满足生物的生理需求，这进一步减少了由于有限的甲烷生成和增强的甲烷硝化作用而产生的CH4排放，并通过加强凋落物的分解削弱了碳的固存。古生态记录也证实了这一点。特别是，在9,500-9,200卡年BP、6,000-4,000卡BP和3,600-3,200卡BP期间，降水导致WTD(WTD>；约30 cm)下降，导致了一系列生态变化，包括湿偏好的泥炭和草本植物减少，好氧细菌活动和生态系统呼吸增强，并改变了土壤碳固定。6,000-4,000大卡BP期间的干旱导致了低碳固存。然而，在9,500-9,200年间和3,600-3,200年间突然的水文变化导致的快速植被演替和泥炭堆积可能导致了碳固存的暂时增加。我们的结果表明，WTD在泥炭地生态功能的调节中起着至关重要的作用。这一发现为泥炭地碳-水循环和管理提供了参考。
Peatlands, one of the largest biosphere carbon reservoirs, are facing climate change induced water-table drawdown and carbon loss. To provide insights into peatland protection and carbon–water cycle under the background of global change, the detailed relationship between peatland ecology and water table depth (WTD) should be considered. In this study, we focused on carbon flux and synthesized datasets on WTD, carbon dynamics, vegetation and microbiologic activities in the Dajiuhu Peatland to better understand the ecological response to the hydrological variations. Based on modern monitoring, the daily CH4emission decreased and CO2emission increased with the fall of the WTD. When the WTD was deeper than 30 cm, daily carbon sequestration reduced until it approached 0 according to nonlinear models. By comparisons with previous spatial soil TOC, vegetation and microbiologic surveys, we proposed that approximately 30 cm is a critical WTD level (turning point or zone) affecting the structure and function of peatland ecosystems. Prolonged and severe droughts might trigger an ecological shift of peatland because increase in oxygen availability and decrease in water availability are not able to meet the physiological needs of living organisms, which further decreases CH4emission due to limited methanogenesis and enhanced methanotrophy and weakens carbon sequestration through enhanced litter decomposition. This was also confirmed by palaeo-ecological records. In particular, precipitation-induced declines of WTD (WTD > 30 cm) during 9,500–9,200 cal yr BP, 6,000–4,000 cal yr BP and 3,600–3,200 cal yr BP caused a series of ecological changes, including the decreases in wet-preferredSphagnumand herbs, enhanced aerobic bacteria activities and ecosystem respiration, and changed soil carbon sequestration. Drought during 6,000–4,000 cal yr BP induced low carbon sequestration. However, rapid vegetation succession and peat accumulation caused by the abrupt hydrological variations during 9,500–9,200 cal yr BP and 3,600–3,200 cal yr BP might have resulted in temporary increases in carbon sequestration. Our results demonstrate that WTD is crucial to the regulation of peatland ecological functions. This finding offers references for peatland carbon–water cycles and management.