Organic Matter Decomposition following Harvesting and Site Preparation of a Forested Wetland

Abstract

Organic matter accumulation is an important process that affects ecosystem function in many northern wetlands. The cotton strip assay (CSA) was used to measure the effect of harvesting and two different site preparation treatments, bedding and trenching, on organic matter decomposition in a forested wetland. A Latin square experimental design was used to determine the effect of harvesting, site preparation, and relative position within the wetland on organic matter decomposition at soil depths of 5, 10, and 20 cm. Repeated measures analysis of variance was used to test for treatment effects on organic matter decomposition, soil temperature, and soil oxidation depth. Cellulose decomposition increased at each soil depth as site disturbance increased, with bedding > trenching > whole-tree harvest > reference. The cellulose decomposition response was correlated with changes in soil temperature; the temperature coefficient Qlo equaled 6.0, which is greater than previously reported values. Position within the wetland relative to an adjoining river affected the decomposition and soil oxidation depth. Because the rate of decomposition is strongly controlled by temperature, higher rates of organic matter decay are expected to continue on harvested and regenerated sites until canopy closure reduces soil temperature.

Vacuum-extraction of peatlands disturbs bacterial population and microbial biomass carbon

“…The oxic zone was determined using steel rods that were placed into the peat at each site, 1 month before sampling. The rod oxidation zone was used to estimate the oxic zone and depth in the peatland (Trettin et al, 1996). The degree of decomposition was determined according to the von Post method (Parent and Caron, 1993).…”

Influence of climate change factors on carbon dynamics in northern forested peatlands

“…There are also other organic-matter-accumulating wetland soils having lesser amounts of surface organic matter that are subject to the same developmental influences and that provide many of the same ecological functions as peatlands. Trettin and Jurgensen (2003) recognized histicmineral soils as having a surface organic accumulation between 5 and 30 cm. "Mire" is a term encompassing both shallow and deep accumulations of soil organic matter, broadly defined as any wetland where organic matter is accumulating on the surface regardless of depth or thickness.…”

“…The effects of climate are evident with productivity generally being higher in the temperate forests, as compared with the boreal forests (Trettin and Jurgensen 2003); however, there is considerable variability among wetland types within a climatic zone. The composition and physiognomy of the peatland vegetation are to a large extent regulated by water table level and soil fertility.…”

“…Peatland productivity ranges between 300 and 1000 g m -2 yr -1 (Reader and Stewart 1972;Grigal et al 1982;Trettin and Jurgensen 2003), with the understory vegetation (i.e., bryophytes, sedges, shrubs) typically comprising a significant proportion of the net C sequestration (Reinikainen et al 1984;Grigal 1985). It is likely that the reported estimates of peatland productivity are low because of the paucity of measurements on below-ground sequestration (Trettin and Jurgensen 2003). Correspondingly, there is considerable uncertainty about the relative contributions of above-and below-ground biomass to the soil organic matter pool in peatlands.…”

“…Hogg et al 1992;Trettin et al 1996). There is an interaction among soil temperature and water table depth Hökkä et al 1997), and under saturated conditions the temperature response may be dampened as a result of a low supply of oxygen and phenol inhibition (Freeman et al 2001).…”