Temporal changes in forest floor carbon stocks following scarification in boreal lichen woodlands

Abstract

ABSTRACT Uncertainties remain regarding the carbon (C) loss due to scarification in afforested lichen woodlands (LW), which originate from regeneration failures of closed-crown black spruce- feathermoss stands due to compounded disturbances. Therefore, the objective of this study was to characterize the C stock changes in the forest floor of scarified, unharvested LWs. Ten afforestation trials were established from 1999 to 2014 in LWs in the managed boreal forest of Québec. Ground surface layers were sampled in 2017 for different microsites. From 3 to 18 years after treatment, scarified floors exhibited ≈ 2 Mg ha−1 C loss, due to opposite trends in the furrow and ridge microsites. Both gradually approached the undisturbed C density level of forest floor between furrow pairs and between skidder trails microsites without reaching it after 18 years. This suggests that microsite C density continued to evolve afterward, and that losses due to scarification might be recovered, due to a higher potential gain in the furrow microsites combined with a lower expected loss in the ridge microsites. Carbon managers should use a permanent 2 Mg ha−1 C loss in the forest floor due to scarification in LWs, acknowledging that this is offset by the growth of planted trees.