Water Storage Characteristics of Several Peats in situ

Abstract

Water storage characteristics of the various horizons in a northern Minnesota bog were found to vary considerably with peat type. Surface horizons of sphagnum moss peat contain 0.020 g. per cc. of dry material and 95 to nearly 100% water by volume at saturation. Its total porosity consisted primarily of large pores which released 0.80 cc. of water per cc. between saturation and 0.1 bar suction.Decomposed and herbaceous peats from horizons below 25 cm. had water-holding properties strikingly different from those of the moss peats. These materials had bulk densities of 0.24 and 0.14 g. per cc., respectively, and they contained between 80 and 90% water by volume at saturation. Their porosity, though high, consisted primarily of many small pores which are not easily drained at low suctions. They retained 65 to 75% water by volume at 0.1-bar suction.These data show that a specific change in water table elevation in the horizons containing loose, porous, undecomposed moss peat would involve a great deal more water than the same change in horizons of more dense decomposed and herbaceous peats. Thus, the hydrologic role of any bog or bog area in a watershed will depend on the type of peat found in the organic soil profile.

A conceptual model of volume-change controls on the hydrology of cutover peats

“…High S y (w0.2-0.5) at the UNDISTURBED site (Price, 1996) moderated the range of WT fluctuation (G26 cm). Similarly, a decreasing trend in q variability from undisturbed to cutover sites (UNDISTURBEDOH97OH92) was observed because retentivity is inversely related to average pore size diameter; the smaller pores at H92 retaining more water upon drainage (see also Boelter, 1965;Okruszko, 1995). The influence of altered pore structure is evident at H92, which had lower K S (10 K5 -10 K7 cm s K1 ) and more variable J (rangeZ42 cm) at 2 cm depth compared to H97 (10 K4 -10 K6 cm s K1 and 36 cm, respectively).…”

Methyl mercury dynamics in a tidal wetland quantified using in situ optical measurements

“…The area of yield was calculated as the volume of the flooding waters during the highest tide occurring in the deployment period divided by the change in water height over that tide, adjusted to account for the water retained in the soils and the volume of the soil itself. We estimated the moisture content to be an average of 50% during drained conditions (Boelter 1964;Weiss et al 1998) and the soil porosity to be 0.9 (Fleck et al 2007), resulting in a contributing area 1.8 times the area defined by the simple water exchange. This method provides a rough estimate of the tidal drainage area, representing approximately 30% of the total island area in Winter, 20% in Fall, and 15% in Spring, consistent with the locations of the sampling stations, which would only capture a fraction of total island drainage.…”

Sphagnum Macrostructure as an Indicator of Decay and Compaction in Peat Cores from an Ombrotrophic South Swedish Peat-Bog

“…To solve this requires (Boelter 1964;Romanov 1968;Ivanov 1981) and reduces its hydraulic conductivity. However, the present study cannot determine whether this is due to differences in microhabitat or in decay resistance among species.…”