Collaborative Research: Water and Carbon Dynamics in Tropical Peat Lands -- Comparison of a Forested Peat Dome with a Deforested Peat Dome in Borneo

合作研究：热带泥炭地的水和碳动态——婆罗洲森林泥炭穹顶与砍伐森林泥炭穹顶的比较

• 批准号: 1114155
• 负责人: Lucy Hutyra
• 金额: $ 31.43万
• 依托单位: Trustees of Boston University
• 依托单位国家: 美国
• 项目类别: Standard Grant
• 财政年份: 2011
• 资助国家: 美国
• 起止时间: 2011-09-01 至 2015-08-31
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=1114155&HistoricalAwards=false
• 关键词: Collaborative; Research; Water; Carbon; Dynamics

Tropical peat forests in Southeast Asia contain vast stores of organic carbon and many of these areas are now rapidly emitting this carbon as they are logged and converted to agriculture. Peat accumulates where the water table is near the surface because saturated conditions maintain anoxia, limiting decay of the peat. Thick peat deposits have likely accumulated over thousands of years because of a positive feedback -- accumulating peat restricts drainage, lifting the water table so more peat can accumulate. Beyond this basic understanding, very little is known about the dynamics of tropical peat forests. What is the sensitivity of tropical peatland coupled H2O/CO2 dynamics to changes in climate? How does peat accumulation or loss depend on seasonality of rainfall? How does peat accumulation depend on nutrient conditions, such as phosphate concentrations? What role, if any, does methane production and consumption play in peat formation or loss? How do lags, legacies, and recovery dynamics of past land use impacts current ecosystem dynamics? What can be done to restore degraded peat lands? To answer these questions, the project is establishing a research site that encompasses two adjacent peat domes, a pristine forested dome and a deforested dome, both on the island of Borneo, in Brunei. All indications are that, prior to deforestation, the ecology of these neighboring domes was indistinguishable. At this site, they will bring together accurate measurements of carbon fluxes over nested time-scales (daily to seasonal to interannual) with analysis of the biogeochemical mechanisms that control peat oxidation and decay. It is hypothesized that most of the fluctuation in net carbon flux from these domes can be predicted from hydrological dynamics, and that the period of maximum carbon uptake (or minimum carbon loss in the deforested site) occurs in the first-stage of dry season when primary productivity increases from higher inputs of photosynthetically active radiation (PAR) and heterotrophic respiration rates remain low because of high water tables. They will also combine near-continuous eddy-flux measurements of CH4 with chamber and dissolved CH4 measurements to create a unique and comprehensive assessment of methane emissions and dynamics.Most tropical peat is found in Southeast Asia and land-use changes are altering hydrologic systems there, breaking the feedback that has caused peat to accumulate. In recent years, peatland degradation and oxidation has been estimated to account for emissions of 0.30 Pg C yr-1 (averaged over 1997-2006), about a quarter of the global CO2 emissions from deforestation and forest degradation. This research, combining data collection and model development, will provide the tools necessary for understanding historical shifts in tropical peat stores, advancing our understanding of the role that tropical peat forests have played in the carbon cycle over geologic history. These tools will also be valuable for managing existing tropical peat lands. The comparison between an undisturbed site and a deforested site will enable us to construct models appropriate to consider the effects of deforestation and development of tropical peat lands, as well as restoration of degraded peatlands. Data collection is enabled in part by on-site support from the Brunei Forestry Department and environmental sensor development activities at the Center for Environmental Sensing and Modeling (CENSAM) based in Singapore and funded by the Science Foundation of Singapore. The project agreement between SMART (an MIT/Singapore collaboration) and the Brunei Forestry Department includes training workshops related to carbon flux measurement and carbon inventories so the methods and knowledge generated through this project can reach local academics, the government, and the broader Bruneian community. A PhD student is to be supported through the MIT-SMART program.

东南亚的热带泥炭林蕴藏着大量的有机碳，其中许多地区在砍伐并转化为农业时，正在迅速排放这些碳。泥炭积聚在地下水位靠近地表的地方，因为饱和条件会维持缺氧，限制泥炭的腐烂。由于正反馈，厚厚的泥炭沉积物可能已经积累了数千年——泥炭的积累限制了排水，抬高了地下水位，因此可以积累更多的泥炭。除了这一基本了解之外，人们对热带泥炭林的动态知之甚少。热带泥炭地耦合 H2O/CO2 动态对气候变化的敏感性如何？泥炭的积累或损失如何取决于降雨的季节性？泥炭积累如何取决于营养条件（例如磷酸盐浓度）？甲烷的产生和消耗在泥炭的形成或损失中发挥什么作用（如果有的话）？过去土地利用的滞后、遗留和恢复动态如何影响当前的生态系统动态？可以采取哪些措施来恢复退化的泥炭地？为了回答这些问题，该项目正在建立一个研究地点，其中包括两个相邻的泥炭圆顶、一个原始森林圆顶和一个被砍伐的圆顶，两个圆顶都位于文莱的婆罗洲岛。所有迹象都表明，在森林砍伐之前，这些邻近圆顶的生态是没有区别的。在这个地点，他们将把嵌套时间尺度（每日到季节到年际）碳通量的精确测量与控制泥炭氧化和腐烂的生物地球化学机制的分析结合起来。据推测，这些圆顶净碳通量的大部分波动可以通过水文动力学来预测，并且最大碳吸收期（或森林砍伐地区最小碳损失期）发生在旱季的第一阶段，此时初级生产力因光合有效辐射（PAR）输入的增加而增加，而异养呼吸速率由于高地下水位而保持较低水平。他们还将近乎连续的 CH4 涡流测量与室测量和溶解 CH4 测量相结合，对甲烷排放和动态进行独特而全面的评估。大多数热带泥炭位于东南亚，土地利用变化正在改变那里的水文系统，打破了导致泥炭积累的反馈。近年来，泥炭地退化和氧化估计造成 0.30 Pg C yr-1 的排放（1997-2006 年的平均值），约占全球毁林和森林退化造成的二氧化碳排放量的四分之一。这项研究结合了数据收集和模型开发，将为理解热带泥炭储存的历史变化提供必要的工具，增进我们对热带泥炭林在地质历史碳循环中所发挥的作用的理解。这些工具对于管理现有的热带泥炭地也很有价值。未受干扰的地点和森林砍伐地点之间的比较将使我们能够构建适当的模型，以考虑森林砍伐和热带泥炭地开发以及退化泥炭地恢复的影响。 数据收集部分得益于文莱林业部的现场支持以及新加坡环境传感和建模中心 (CENSAM) 的环境传感器开发活动，并由新加坡科学基金会资助。 SMART（麻省理工学院/新加坡合作项目）与文莱林业部之间的项目协议包括与碳通量测量和碳清单相关的培训研讨会，以便通过该项目产生的方法和知识可以惠及当地学者、政府和更广泛的文莱社区。 博士生将通过 MIT-SMART 计划获得支持。