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Studies of mire hydrology and carbon accumulation have shown 1) an exponential increase in the rate of horizontal water movement with increasing height of the water table, and 2) a curvilinear relationship between the water table elevation and carbon accumulation rate, with a single maximum. Equations for these relationships suggest that optimal carbon accumulation will occur where the water table is at moderate depth and the surface has little microtopography. Wet conditions tend to enhance microtopographic relief by differential peat accumulation, while dry conditions tend to reduce relief. For mires with abundant dry microsites, increasing the water supply typically increases the rate of carbon accumulation, but this effect could be transient because microtopographic relief may also increase and have a negative effect on carbon accumulation. The runoff-inhibiting nature of ridge and hollow patterns makes patterned mires especially vulnerable to loss of carbon fixation ability with increasing wetness. While dry periods often cause peat loss in the short term, over the long term their effect may be positive because they hinder the formation of strong microtopography. This helps explain why high peat accumulation rates and some of the world’s most extensive peatlands occur in continental regions with a marginally adequate moisture supply.
-
Swanson,
USDA Forest Service, PO Box 907, Baker City, OR 97814 USA
Sähköposti:
ei.tietoa@nn.oo
