deMontigny, L.E., C.M. Preston, P.G. Hatcher, and I. Kogel-Knaber, 1993. I. Comparison of humus horizons from two ecosystem phases on northern Vancouver Island using C-13 CPMAS NMR spectroscopy and CuO oxidation. Can. J. Soil Sci. 73:9-25.

Solid-state 13C nuclear magnetic resonance (NMR) spectroscopy and CuO oxidation was used to examine whether chemical differences in the humus is associated with forest productivity after clearcutting. Humus was sampled from sites with two distinct ecosystem phases: a young HA phase with a history of soil disturbance which is productive after clearcutting, and an older CH phase which has remained undisturbed for _ 1000yr where seedlings suffer a growth check 5-8 yr after clearcutting. NMR spectra of woody horizons, of CH and HA sites, were both dominated by lignin of decomposed wood. Non-woody humus types were typical of forest litter layers, and were dominated by signals in the O-alkyl region. The differences between CH and HA sites were: (i) higher tannin content in the CH sites; and (ii) higher ratio of carbohydrate to lignin C, indicating less effective decomposition in CH sites. Oxidation with CuO also showed more advanced decomposition in the non-woody horizons of HA than of CH sites. Less effective decomposition due in part to tannin accumulation would contribute to the lower forest productivity on salal-dominated (Gaultheria shallon) CH sites in this region.