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Fourteen kg ha-1 yr-1 of N enter the mire acrotelm, and 12 are sequestered in the catotelm peat. However, 66 kg ha-1 yr-1 cycle between plant growth and decay in the acrotelm each year, primarily as ammonium and organic N. Fifty eight percent of the sulfate inputs to the mire are retained, but the export of organic sulfur (1.5 kg ha-1 yr-1) yields a total sulfur retention of 37%. As with N, recycling within the acrotelm and vegetation layer is large (12.5 kg ha-1 yr-1). The proton cycle in the mire is dominated by nutrient uptake and plant decay (about 80% of the 1 044 meq m-2 yr-1). Organic acid production is the major source of free acidity (263 meq m-2 yr-1) and buffers the water near pH 4. About half of the metals entering the mire are retained, and about 60% of the P is retained. Retention of P is particularly high (about 80%) during the spring snowmelt season. The carbon cycle at the Marcell mire consists of about 655 g C m-2 yr-1entering and leaving the acrotelm and vegetation. Eighteen to 28 g C m-2 yr-1are sequestered each year in the catotelm (true and apparent rate of accumulation). Net primary production in the moss, tree, and herbaceous layers accounts for about 385 g C m-2 yr-1, while C02 losses in soil and plant respiration account for about 589g C m-2 yr-1. Root net primary productivity (unmeasured) is estimated at 152 g C m-2 yr-1. Water export of C is 37 and methane losses are about 6 g C m-2 yr-1.
Keywords: Carbon cycling, global change, Minnesota, nutrient budgets, peatlands
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Verry,
USD A- Forest Service, North Central Forest Exp. Stn., 1831 Highway 169 East, Grand Rapids, MN, USA.
Sähköposti:
ei.tietoa@nn.oo
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Urban,
Sähköposti:
ei.tietoa@nn.oo
