Coastal Ecosystems: Climate Change and Anthropogenic Impacts

盐沼是被海洋潮汐淹没的长满草的草甸，是特殊的碳汇，因为它们的植被固定了大气中的二氧化碳，并将其储存在土壤中数千年。我的研究项目将量化加拿大两个盐沼中这种下沉的程度。同时，我将研究沼泽可能排放的甲烷和一氧化二氮这两种温室气体。这些气体的排放抵消了储存的碳的价值，因为它们在全球变暖方面比二氧化碳更有效。通过比较碳储存和温室气体排放的速度，我们可以评估盐沼潜在的气候反馈，以及它们过去或未来的损失可能会如何影响气候。正在进行的沼泽肥沃试验将纳入这项研究，以确定向沿海土地和水域释放的过量营养物质将如何影响气体排放，从而影响气候反馈。这项研究将对环境保护具有直接的价值，因为它将使我们能够从碳储存及其气候影响的角度来估计防止盐沼损失或恢复沼泽的价值。事实上，储存在盐沼中的碳被称为“蓝碳”，现在正在考虑用于碳抵消计划，预计出售蓝碳信用额度将促进沿海沼泽的保护和养护。然而，我们还没有准确地记录整个沼泽中储存的碳的数量或比率。我们也没有对温室气体排放的潜力进行全面评估，因为温室气体排放可能会降低碳的经济价值。我的研究试图通过回答以下问题来填补这一空白：1)沼泽中的碳储量和储存率是如何变化的；什么是控制措施，什么是储存的最佳预测因素？3)温室气体排放的变化有多大，控制措施是什么，哪些变量是这些排放量的最佳预测因素？4)营养丰富如何影响储存潜力和气体排放？这些问题的答案也将对海岸管理的规划有价值。

Salt marshes, grassy meadows flooded by ocean tides, are exceptional carbon sinks as their vegetation fixes carbon dioxide from the atmosphere and stores it in the soil for millennia. My research program will quantify the magnitude of this sink in two Canadian salt marshes. At the same time I will examine the potential for emissions of methane and nitrous oxide, two greenhouse gases that can be emitted from marshes. Emissions of these gases counter the value of stored carbon as they are more potent than carbon dioxide in terms of global warming. By comparing the rates of carbon stored and greenhouse gases emitted we can assess the potential climate feedbacks of salt marshes and how their loss in the past, or future, might affect climate. Ongoing experiments of fertilized marshes will be incorporated into this study to see determine how excess nutrients released to coastal lands and waters will affect gas emissions, thus climate feedbacks. This research will have immediate value to conservation because it will enable us to estimate the value of preventing salt marsh loss or restoring marshes in terms of carbon storage and its climate ramifications. In fact, the carbon stored in salt marshes, called "Blue Carbon", is now being considered for carbon offset programs with expectation that sale of Blue Carbon credits will stimulate preservation and conservation of coastal marshes. However, we have yet to accurately document the amount the amount or rate of carbon stored within an entire marsh. Neither have we performed a comprehensive assessment of the potential for greenhouse gas emissions that could reduce the economic value of the carbon. My research seeks to fill this void by answering the following questions: 1) How do carbon stocks and storage rates vary within a marsh; what are the controls, and what are best predictors of the storage? 3) How much do greenhouse gas emissions vary, what are the controls, and what variables are best predictors of those rates? 4) How does nutrient enrichment affect the storage potential and gas emissions? Answers to these questions will be valuable to planning for coastal management as well.