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C悖论，具有巨大的C储存能力，但也是甲烷的强大来源（CH4）。鉴于对雨水和地下水的依赖性，全球湿地对气候变化非常敏感。饱和度的季节性转移有可能以CO2和CH4的形式导致高度动态的温室气体（GHG）通量。热带湿地特别研究了，但对全球CH4预算做出了巨大的贡献。尽管巴西拥有广阔的湿地，但以前的工作主要集中在永久饱和的系统上，例如亚马逊或泛岩洪泛区。相比之下，研究不足的塞拉多域包括永久（泥炭地）和季节性淹没的（季节性草原），湿地和干草原，饱和季节性转移。气候变化可能会给该地区带来更温暖，更干燥的条件，增加了季节性和干燥草地的区域，以及温室气体排放的潜力增加。鉴于当前对观察结果的匮乏和预测这些关键季节性系统未来的重要性，确定驱动饱和梯度的温室气体排放和C存储的机制至关重要，以及这些系统在这些系统的空间范围内的变化。我们的总体目标是克服巴西站点的这些知识差距。我们在Cerrado热带草原的联合田地和建模方法将重点放在回答三个问题上：Q1。在饱和梯度跨饱和梯度的海存储中的空间和时间异质性的驱动因素是什么？ Q2。热带草原的饱和度（区域和周长）如何改变盒子？季节性和十年尺度？ Q3。在未来气候下，热带草原的海洋排放率和形式将如何变化？为了测试Q1，空间分布的测量将与高颞分辨率测量结果结合，以了解整个饱和梯度的温室气体，土壤和植被C动力学。温室气体变异性将用静态通量室进行空间测量，并用自动腔室进行时间测量。时间变化的时间将取决于初始土壤表征，并结合植物物候，气孔电导，孔隙水化学，基线气候和季节性地下水的季节性测量。为了测试Q2，将将高分辨率的遥感和现场参考数据合并为绘制湿地范围，季节性14C和210pb年代将用于了解衰老尺度下的湿地范围变化。为了测试Q3，来自Q1和Q2的数据将用于模拟与Pflotran反应性传输模型耦合的E3SM陆地模型。 C隔离模式和温室气体排放的估计值将通过C平衡变化和温室气体变化的投影与区域气候和水文学的预期变化进行空间模拟。