Constraining the Relationship Between Vegetation Change and Net Carbon Sequestration in Arctic and Boreal Peatlands

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Peat-forming ecosystems are key components of the global carbon cycle, as they are tremendous stores of carbon from carbon dioxide in the atmosphere. But peatlands also release methane back to the atmosphere. The degree to which peatlands act as carbon sinks and methane sources largely depends on the types of plants growing there. The far northern areas where Arctic peatlands occur are warming rapidly and so it is important to determine how sensitive their carbon storages are to changes in vegetation that are already underway. It is known that when the main peatland plants change from sphagnum mosses to sedges, as is happening in many areas, the rate of carbon storage may change a lot, but the specific response of any particular peatland is not easy to predict. Much of the unpredictability results from difficulties in telling apart the dominant plants in peatlands through history. If that was possible, then much better predictions into the future could be made. So the main objective of this project is to create a database of the chemical properties of Arctic sedges and other plants known to dominate peatlands in the past. The database will be available to the public and be set up so that it can be easily updated and added to. The project will also continue a program that brings high school teachers from the New York area to the arctic to participate in field studies associated with the project. These teachers will then develop teaching modules connected to high school science curriculums. Members of the Cyperaceae (sedges) inhabit diverse environments, spanning a wide range of moisture balance, pH, and nutrient availability. However, they are notoriously difficult to identify by their fossil remains in peat cores, even to the family level, because of the paucity of identifiable plant parts that are species specific. But while the plant parts themselves are often absent, chemicals they produced are almost always present. Of the thousands of compounds produced, most have yet to be properly characterized and linked to particular species. This project will generate such a database and will also relate vegetation types, as characterized by their chemical constituents, to net carbon accumulation rate. In doing so, the first predictive models of carbon accumulation in peatlands based on vegetation change will be developed. This is an important step towards fully integrating peatlands into global climate models, which will allow a more comprehensive understanding of the feedbacks between climate change and peatland carbon accumulation.