Response of a Tundra Ecosystem to Elevated Atmospheric Carbon Dioxide and CO 2 -Induced Climate Change: A Renewal Research Proposal
Northern ecosystems contain up to 455 Gt of C in the soil active layer and upper permafrost. The soil carbon in these layers is equivalent to approximately 60% of the carbon currently in the atmosphere as CO 2 . Much of this carbon is stored in the soil as dead organic matter. Its fate is subject to...
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2020
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| Online Access: | http://www.osti.gov/servlets/purl/230262 https://www.osti.gov/biblio/230262 https://doi.org/10.2172/230262 |
| Summary: | Northern ecosystems contain up to 455 Gt of C in the soil active layer and upper permafrost. The soil carbon in these layers is equivalent to approximately 60% of the carbon currently in the atmosphere as CO 2 . Much of this carbon is stored in the soil as dead organic matter. Its fate is subject to the net effects of global change on the plant and soil systems of northern ecosystems. The arctic alone contains about 60 Gt C, 90% of which is present in the soil active layer and upper permafrost. The arctic is assumed to have been a sink for CO 2 during the historic and recent geologic past. The arctic has the potential to be a very large, long-term source or sink of CO 2 with respect to the atmosphere. In situ experimental manipulations of atmospheric CO 2 , indicated that there is little effect of elevated atmospheric CO 2 on leaf level photosynthesis or whole-ecosystem CO 2 flux over the course of weeks to years, respectively. However, there may be longer-term ecosystem responses to elevated CO 2 that could ultimately affect ecosystem CO 2 balance. In addition to atmospheric CO 2 , climate may affect net ecosystem carbon balance. Recent results indicate that the arctic has become a source of CO 2 to the atmosphere. This change coincides with recent climatic variation in the arctic, and suggests a positive feedback of arctic ecosystems on atmospheric CO 2 and global change. Measurements along a latitudinal gradient across the north slope of Alaska indicate a loss of carbon from tussock tundra of 156 g m -2 y -1 , and from the wet tundra of 34 g m -2 y -1 . If these rates are representative of the circumpolar tundra, then they equate to a net annual global loss of carbon as CO 2 to the atmosphere of 0.17 Gt C, 0.14 Gt from tussock tundra, and 0.03 Gt from wet coastal tundra. Depending on the nature, rate, and magnitude of global environmental change, the arctic may have a positive or negative feedback on global change. At present, the initial response of the arctic indicates a net loss of carbon to the atmosphere ... |
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