Prescribed burning of harvested boreal black spruce forests in eastern Canada: effect on understory vegetation

Abstract

Ecosystem-based management advocates that forestry disturbances should aim to emulate natural disturbances to mitigate the landscape-level impact of forest management. This study compares the impact of clear-cuts followed by a prescribed burn (CCPB) with clear-cuts alone (CC) and current careful logging practices (CLAAG: “careful logging around advanced growth”) on understory composition within black spruce (Picea mariana Miller (BSP)) paludified forest stands at the plot, site, and treatment levels using a functional-type approach. Vascular and nonvascular taxa showed significant differences in composition at the plot level among treatments. We found that pioneer taxa occurred mainly in CCPB sites, while late-successional taxa characterized CC sites. CLAAG sites had higher taxa richness than CCPB and CC sites, and we found that CCPB treatments were most likely to promote vascular taxa compositions that are more similar to those observed after natural disturbances. Additionally, the relative abundance of Sphagnum spp., responsible for paludification, was significantly reduced in sites treated by prescribed burning. This study therefore presents results suggesting that prescribed burning might represent a sustainable alternative to current harvesting techniques in the Clay Belt of eastern Canada that could help in preserving biodiversity (in terms of understory species assemblage) while maintaining or even enhancing forest productivity.

Carbon storage and understory plant diversity in boreal Larix gmelinii–Carex schmidtii forested wetlands: A comparison of harvest, fire and draining disturbance

“…The lower abundance of larch regeneration in selective harvest plots was in agreement with the study which has reported reduced seed supply and lack of suitable microsites limites regenetation in these forested wetlands (Greene et al, 2007). Post-harvest understory communities are more similar to pre-harvest communities, with the exception of late successional shade intolerant species that do not survive stand opening caused by harvesting (Faivre et al, 2016). Additionally, large diameter trees of larch have not been burned to death, but most of birch trees died in the heavy fire, suggesting large larch is more fire-resistant than birch.…”

Understory vascular plant responses to retention harvesting with and without prescribed fire

“…Managed forests should contain early-successional forests, which are critical for habitat specialists and disturbance-adapted species (Swanson et al 2011;Fedrowitz et al 2014). Prescribed burning after harvest has been suggested as a tool for promoting the unique substrates and habitats critical for fire-specialized species (McRae et al 2001;Hart and Chen 2006;Vanha-Majamaa et al 2007;Brassard and Chen 2010;Halpern et al 2012;Faivre et al 2016). When combined with aggregated tree retention, prescribed fire promoted the recovery of some plant species that have winddispersed seeds (Johnson et al 2014).…”