Modeling Soil and Biomass Carbon Responses to Declining Water Table in a Wetland-Rich Landscape
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odeling Soil and Biomass Carbon Responses to Declining Water Table in a Wetland-Rich Landscape Benjamin N. Sulman,1,2* Ankur R. Desai,2 and David J. Mladenoff3 1
Princeton Environmental Institute, Guyot Hall Room 129, Princeton University, Princeton, New Jersey 08544, USA; 2Department of Atmospheric and Oceanic Sciences, University of Wisconsin-Madison, 1225 W, Dayton St., Madison, Wisconsin 53706, USA; 3 Department of Forest and Wildlife Ecology, University of Wisconsin-Madison, 1630 Linden Dr., Madison, Wisconsin 53706, USA
ABSTRACT for both scenarios. Long-term carbon cycle responses were not significantly affected by the time scale of water table decline. In general, peatland carbon storage over the first 50–150 years following drainage was neutral or increasing due to increased plant growth, whereas carbon storage over longer time scales decreased due to soil carbon loss. Although the simplicity of the model limits quantitative interpretation, the results show that plant community responses are essential to understanding the full impact of hydrological change on carbon storage in peatland-rich landscapes, and that measurements over long time scales are necessary to adequately constrain landscape carbon pool responses to declining water table.
Peatlands and forested wetlands can cover a large fraction of the land area and contain a majority of the regional carbon pool in wet northern temperate landscapes. We used the LANDIS-II forest landscape succession model coupled with a model of plant community and soil carbon responses to water table changes to explore the impacts of declining water table on regional carbon pools in a peatland- and wetland-rich landscape in northern Wisconsin, USA. Simulations indicated that both biomass accumulation and soil decomposition would increase as a consequence of drying. In peatlands, simulated water table declines of 100 cm led to large increases in biomass as well as shortterm increases in soil carbon, whereas declines of 40 cm led to continuous declines in soil carbon and smaller increases in biomass, with the net result being a loss of total carbon. In non-peat wetlands, biomass accumulation outweighed soil carbon loss
Key words: wetlands; peatlands; drainage; carbon cycle; hydrological change; plant community succession; LANDIS-II model.
INTRODUCTION Northern peatlands contain a significant fraction of the global terrestrial carbon pool, and the future evolution of peatland carbon reserves is an important factor in predicting carbon cycle feedbacks to climate change (Gorham 1991; Turunen and others 2002; Mitra and others 2005). In northern temperate regions, peatlands can cover a large fraction of the area, contain significant portions of the carbon pool, and contribute significantly to the regional carbon budget. For example, Weishampel and others (2009)
Received 3 July 2012; accepted 22 October 2012; published online 14 December 2012 Author Contributions: B.N.S. designed study, ran and analyzed simulations, wrote manuscript. A.R.D. contributed to study design and int
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