Downed Woody Material Dynamics
Shawn Fraver, Mike Saunders and Bob Wagner
Research on DWM has unequivocally established its importance in forest ecosystem function. Harvesting, therefore, can substantially alter ecosystem function and structure by removing material that would otherwise comprise future DWM (Figure 3.1). While many studies have documented volumes of DWM in old-growth forests, few studies of DWM have looked at the influence of silviculture on DWM volumes and structures in actively managed stands. The FERP stands were an excellent area to study these influences. Pre- and post-harvest inventories of DWM by species and by decay class were conducted within all plots of the 9 FERP stands. Additionally, samples of DWM were collected for volume/mass estimation and nutrient analysis. Preliminary results show that harvesting significantly increases the volume and the biomass (Figure 3.2) of DWM in the lower decay classes. Additionally, harvesting tends to fragment DWM into more pieces which increases surface area and may reduce residence time on the forest floor. Levels of several common plant nutrients vary significantly by species and decay class. DWM of hardwood species had consistently higher nutrient levels than softwood species regardless of decay class (Figure 3.3). Future work in this area will incorporate volume and biomass data with nutrient analyses to estimate the effect of harvesting on total nutrient pools.
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| Figure 3.2 (above). Influence of harvesting treatments (20-10, 10-30 and CTRL) on biomass of DWM in each decay class. Trends for volume of DWM were similar. | ||||
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| Figure 3.1 (above). Harvesting usually removes large-diameter DWD from the stand. | ||||
| Figure 3.3 (above). Carbon/Nitrogen ratios with the 4 decay classes for hardwood and softwood species. | ||||