NSFDEB-NERC: Spatial and temporal tradeoffs in CO2 and CH4 emissions in tropical wetlands

NSFDEB-NERC：热带湿地二氧化碳和甲烷排放的时空权衡

• 批准号: NE/Z000246/1
• 负责人: Angela Gallego-Sala
• 金额: $ 31.86万
• 依托单位: UNIVERSITY OF EXETER
• 依托单位国家: 英国
• 项目类别: Research Grant
• 财政年份: 2025
• 资助国家: 英国
• 起止时间: 2025 至 无数据
• 项目状态: 未结题
• 来源: https://gtr.ukri.org/projects?ref=NE%2FZ000246%2F1
• 关键词: NSFDEB; NERC; Spatial; temporal; tradeoffs

Wetlands are a C paradox, with huge capacity for C storage but also a strong source of C as methane (CH4). Wetlands worldwide are highly sensitive to climate change, given dependencies on rain and groundwater. Seasonal shifts in saturation have potential to lead to highly dynamic greenhouse gas (GHG) fluxes, in the form of CO2 and CH4. Tropical wetlands are particularly understudied but make outsized contributions to the global CH4 budget. Though Brazil has vast wetlands, previous work largely focused on permanently saturated systems, e.g., Amazon or Pantanal floodplains. In contrast, the poorly studied Cerrado domain includes permanent (peatlands) and seasonally inundated (seasonal grasslands), wetlands and dry grasslands, with saturation shifting seasonally and episodically. Climate change is likely to bring warmer and drier conditions to this region, increasing areas of seasonal and dry grasslands and concomitant potential increases in GHG emissions. Given current paucity of observations and importance of predicting future of these critical seasonal systems, it is vital to determine mechanisms driving spatial and temporal shifts in GHG emissions and C storage across the saturation gradient, as well as changes in spatial extent of these systems through time. Our overall objective is to overcome these knowledge gaps in sites in Brazil. Our combined field and modeling approaches in Cerrado tropical grasslands will focus on answering three questions: Q1. What are the drivers of spatial and temporal heterogeneity in sea storage and flux across saturation gradients? Q2. How does saturation extents (areas and perimeters) in tropical grasslands change over box? Seasonal and decadal scales? Q3. How will rates and forms of sea emissions from tropical grasslands change under future climates? To test Q1, spatially distributed measurements will be coupled with high-temporal resolution measurements to understand GHG, soil and vegetation C dynamics across the saturation gradient. GHG variability will be measured spatially with static flux chambers and temporally with automated chambers. Site changes through time will be determined by initial soil characterization, combined with seasonal measurements of plant phenology, stomatal conductance, porewater chemistry, baseline climate and groundwater seasonally. To test Q2, high resolution remote sensing and field reference data will be combined to map wetland extent, seasonally 14C and 210Pb dating will be used to understand wetlands extent changes at decadal scales. To test Q3, data from Q1 and Q2 will be utilized in simulations with E3SM Land Models coupled to PFLOTRAN reactive transport models. Estimates of C sequestration patterns and GHG emissions will be spatially simulated with projections of C balance changes and GHG with expected shifts in regional climate and hydrology.

湿地是一个碳悖论，具有巨大的碳储存能力，同时也是甲烷（CH4）的重要来源。世界各地的湿地对气候变化高度敏感，因为它们依赖雨水和地下水。饱和度的季节变化有可能导致以CO2和CH4形式存在的高度动态的温室气体通量。热带湿地的研究尤其不足，但对全球CH4预算的贡献却很大。虽然巴西有广阔的湿地，但以前的工作主要集中在永久饱和的系统，例如亚马逊或潘塔纳尔洪泛平原。相比之下，研究较少的Cerrado域包括永久性（泥炭地）和季节性淹没（季节性草原），湿地和干草地，其饱和度随季节和偶然变化。气候变化可能会给这一地区带来更温暖和更干燥的环境，增加季节性和干旱草原的面积，并伴随潜在的温室气体排放增加。鉴于目前观测的缺乏和预测这些关键季节系统未来的重要性，确定驱动温室气体排放和碳储存在饱和梯度上的时空变化的机制以及这些系统的空间范围随时间的变化是至关重要的。我们的总体目标是克服巴西各地点的这些知识差距。我们在塞拉多热带草原的综合实地和建模方法将专注于回答三个问题：海洋储水量和通量在饱和梯度上的时空异质性的驱动因素是什么？Q2。热带草原的饱和范围（面积和周长）如何变化？季节和年代际尺度？第三季。在未来的气候条件下，热带草原海洋排放的速率和形式会发生怎样的变化？为了验证第1题，空间分布测量将与高时间分辨率测量相结合，以了解温室气体、土壤和植被C在饱和度梯度上的动态。温室气体变率将在空间上用静态通量室测量，在时间上用自动通量室测量。地点随时间的变化将由最初的土壤特征，结合植物物候、气孔导度、孔隙水化学、基线气候和地下水的季节性测量来确定。为了验证Q2，将结合高分辨率遥感和野外参考数据来绘制湿地范围，并使用14C和210Pb季节定年来了解湿地范围在年代际尺度上的变化。为了测试第三季度，第一季度和第二季度的数据将用于E3SM陆地模型与PFLOTRAN反应性输运模型的模拟。对碳固存模式和温室气体排放的估算将在空间上进行模拟，并对碳平衡变化和温室气体进行预估，并对区域气候和水文的预期变化进行预估。