Downed Woody Debris

(Fraver, Saunders, and Wagner) - Volume, biomass, diameter-class and decay-class distributions of downed woody debris (DWD) were quantified in permanent plots before and three years after harvest. Wood density and moisture content by species and decay class also was measured. Mean pre-harvest DWD volume was 27.2 m³/ha and biomass 5.8 Mg/ha. Both harvesting treatments increased the volume and biomass of non-decayed, small-diameter CWD (i.e., logging slash), with the 20% treatment showing a greater increase than the 10% treatment and both treatments showing greater increases than the control. Post-harvest reduction of advanced-decay DWD due to mechanical crushing was not evident. A mean of 4.6 m³ water/ha demonstrates substantial water storage in DWD, even during an exceptionally dry sampling period. The U-shaped temporal trend in DWD volume or biomass seen in even-aged stands may not apply to these uneven-aged stands; here the trend is likely more complex because of the superimposition of small-scale natural disturbances and repeated silvicultural entries. Nutrient analysis of this work indicates that DWD from hardwood species generally had higher nutrient content than from softwood species in comparable decay classes.