Large amounts (389 ± A 39 m3 ha-1) of preserved dead wood buried by bryophytes were found in the organic layer (OL) of overmature (146- to 204-year-old) black spruce (Picea mariana (Mill.) B.S.P.) forests in the high-boreal forest of eastern Canada. Stand-replacing wildfires consumed the organic layer and killed the previous stands, producing snags, which subsequently fell and became buried by moss, resulting in large amounts of wood buried deep in the current organic layer. As new forest stands developed, self-thinning and senescence continuously produced minor amounts of woody debris (WD) for burial, most of which was located in the upper half of the organic layer. The experimental burial of standardized sample logs at various depths in the organic layer showed that burial significantly decreased WD temperature, increased WD moisture content, and tended to decrease WD respiration rates, indicative of reduced decomposition activity. WD preservation may be initiated by a live bryophyte cover, providing thermal insulation and moisture retention, generating an environment unfavorable to decomposition. As bryophytes are a vital component of many coniferous ecosystems throughout the circumpolar boreal and mountain forests, conditions conducive to WD burial are likely widespread. Buried wood may thus be of global relevance as habitat and a large mid- to long-term carbon store. © 2010 UKCrown: Natural Resources Canada, Canadian Forest Service - Atlantic Forestry Centre.