(13)CPMAS-NMR SPECTROSCOPY AND CHEMICAL-ANALYSIS OF COARSE WOODY DEBRIS IN COASTAL FORESTS OF VANCOUVER-ISLAND

The coastal forests of British Columbia have large accumulations of co arse woody debris, and information on this pool is considered essentia l in developing sustainable management practices. We characterized coa rse woody debris (7-12 and >12 cm diameter) in forest chronosequences of four age classes located on the eastern and western sides of Vancou ver Island. For three species (Douglas-fir (Pseudotsuga menziesii (Mir b.) France), western hemlock (Tsuga heterophylla (Raf.) Sarg), western red cedar (Thuja plicata Donn.)) and unidentified samples, increases in decay class (I to V, assigned in the field) were associated with de creasing density, and small increases in concentrations of C, N, and P . Sulfur concentrations (0.6-2.4 g/kg) were higher than those found el sewhere for wood and did not show any significant changes with decay c lass. C-13 nuclear magnetic resonance spectroscopy with cross polariza tion and magic-angle spinning (C-13-CPMAS-NMR) was used to analyze org anic components in a subset of samples >12 cm. Logs up to decay class III generally showed little change in composition or a slight increase in polysaccharide C. After this, polysaccharide was lost more quickly and logs of decay class V were composed almost entirely of lignin, a pattern consistent with decay by brown-rot fungi. However, two samples of western red cedar decay class III and IV showed accumulation of po lysaccharide, the pattern expected from white-rot fungi. The results o f the density, chemical and NMR analysis indicate that for management purposes, a system with fewer decay classes would suffice. (C) 1998 El sevier Science B.V.