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

东南亚的热带泥炭森林含有大量的有机碳，其中许多地区现在正在迅速排放这些碳，因为它们被砍伐并转化为农业。泥炭在地下水位接近地表的地方积累，因为饱和的条件保持缺氧，限制了泥炭的腐烂。厚厚的泥炭沉积物可能是数千年来积累起来的，因为一个积极的反馈-积累泥炭限制排水，提高地下水位，使更多的泥炭可以积累。除了这些基本的了解，对热带泥炭森林的动态知之甚少。热带泥炭地耦合H2O/CO2动力学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？泥炭的积累如何取决于营养条件，如磷酸盐浓度？如果有的话，甲烷的产生和消耗在泥炭的形成或损失中起什么作用？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？如何恢复退化的泥炭地？为了回答这些问题，该项目正在建立一个研究地点，包括两个相邻的泥炭圆顶，一个原始森林圆顶和一个森林砍伐圆顶，都在文莱的婆罗洲岛。所有迹象都表明，在森林砍伐之前，这些邻近圆顶的生态是无法区分的。在这个地点，他们将在嵌套的时间尺度（每日到季节到年际）上对碳通量进行精确测量，并分析控制泥炭氧化和腐烂的地球化学机制。据推测，这些圆顶的净碳通量的波动大部分可以预测从水文动力学，最大的碳吸收（或最小的碳损失在毁林网站）的时期发生在旱季的第一阶段，当初级生产力增加，从较高的光合有效辐射（PAR）和异养呼吸率的输入仍然很低，因为高水位。他们还将把联合收割机对甲烷的近连续涡流通量测量与室内和溶解甲烷测量相结合，以建立对甲烷排放和动态的独特和全面的评估。近年来，泥炭地退化和氧化估计造成0.30 Pg C yr-1的排放量（1997 - 2006年的平均值），约占全球毁林和森林退化造成的CO2排放量的四分之一。这项研究，结合数据收集和模型开发，将提供必要的工具，了解热带泥炭存储的历史变化，推进我们对热带泥炭森林在地质历史上的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。未受干扰的网站和毁林网站之间的比较，将使我们能够构建适当的模型，考虑森林砍伐和热带泥炭地的发展，以及退化泥炭地的恢复的影响。 数据收集部分是由文莱林业部的现场支持和环境传感器开发活动在环境传感和建模中心（CENSAM）设在新加坡和新加坡的科学基金会资助。SMART（麻省理工学院/新加坡合作）和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，因此通过该项目产生的方法和知识可以到达当地学者，政府和更广泛的文莱社区。 一个博士生将通过麻省理工学院的SMART计划得到支持。

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.