The soil acid–base status of boreal black spruce stands after whole-tree and stem-only harvesting

Abstract

The effect of different harvesting practices on soil acid–base status was evaluated in black spruce (Picea mariana (Mill.) BSP) forests of Quebec by comparing soil from five pairs of whole-tree and stem-only harvested plots 3 years after harvest. Stem-only harvesting contributed to the enrichment of the exchangeable base cation pool, particularly in the forest floors of the pairs where whole-tree harvested plots showed the highest exchangeable Al3+. In the mineral soil, divergence between treatments was low, perhaps because these acidic soils were strongly saturated with Al3+ (about 90%), which did not favour cationic exchange reactions. Although the effects of treatment may not persist over time, improved base cation nutrition may benefit stands during the early stages of development. Over a forest rotation of about 85 years, the estimated loss of alkalinity due to whole-tree harvesting was estimated to be low (less than 20%) when compared with the effect of acidic deposition.