Dynamics of coarse woody debris following gap harvesting in the Acadian forest of central Maine, USA

We examined the dynamics of down coarse woody debris (CWD) under an expanding-gap harvesting system in the Acadian forest of Maine. Gap harvesting treatments included 20% basal area removal. 10% basal area removal, and a control. We compared volume, biomass, diameter-class, and decay-class distributions of CWD in permanent plots before and 3 years after harvest. We also determined wood density and moisture content by species and decay class. Mean pre-harvest CWD volume was 108.9 m(3)/ha, and biomass was 23.22 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 CWD due to mechanical crushing was not evident. A mean of 18.48 m(3) water/ha (1.85 L/m(2)) demonstrates substantial water storage in CWD, even during an exceptionally dry sampling period. The U-shaped temporal trend in CWD 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.