Deadwood abundance in Labrador high-boreal black spruce forests

Abstract

Deadwood (woody debris (WD), standing dead trees (snags), stumps, and buried deadwood) abundance was estimated in Labrador humid high-boreal black spruce (Picea mariana (Mill.) BSP) forests regrown following natural and anthropogenic disturbances. Aboveground deadwood (DW) abundance in Labrador was similar to values observed in other boreal forests experiencing drier or warmer climates. Clear-cut harvest generated large amounts of WD, which had almost completely decomposed 34–36 years following harvesting, with a fitted volume reduction rate of –0.058 year–1. Total WD in all harvested stands was composed of predominantly <10 cm pieces, which should be included in DW inventories of disturbed coniferous boreal forests. Postfire WD likely peaked ∼20 years following disturbance, as a result of the collapse of snags, and was dominated by large amounts of medium-sized logs (10.0–19.9 cm). Buried DW stocks considerably exceeded total aboveground DW stocks in old-growth, middle-aged, and older harvested stands. Old-growth stands contained 179.3 m3·ha–1 of buried DW, a vast amount indicative of long-term accumulation requiring significantly depressed rates of WD decomposition following burial. DW stocks could be significantly underestimated if buried DW is excluded from DW inventories in cool and moist coniferous forests with long fire-return intervals.