Effects of slash harvest on bryophytes and vascular plants in southern boreal forest clear‐cuts

Abstract

Summary1. Slash harvesting from forests to provide bioenergy reduces the amount of woody debris in the managed forest landscape and changes the physical and chemical environment in clear-cuts. We examined previously unstudied effects of commercial (i.e. nonexperimental) slash harvest on species composition and richness of liverworts, mosses and vascular plants. The results call for modification of commercial slash harvest practices. 2. Differences between conventionally harvested (i.e. slash left) and slash-harvested stands were investigated 5-10 years after clear-cutting through analysis of 28 paired stands, with one 0·1-ha plot divided into five 0·02-ha subplots in each stand. 3. The species composition of mosses and liverworts in 0·1-ha plots was significantly affected by slash harvest, whereas the composition of vascular plant species was not. 4. The species richness of liverworts was significantly reduced by slash harvest in plots of both sizes, whereas moss richness was reduced only in 0·02-ha plots. The loss of liverwort species was largest, with approximately one-third of the species disappearing. The species richness of vascular plants was not significantly affected by slash harvest in either plot size. 5. Slash harvest reduced species richness of forest bryophytes and of bryophytes typically growing on organic substrates in open habitats. Species richness of non-forest bryophytes on inorganic substrates remained unchanged. 6. Synthesis and applications. Our results show that slash harvest reduces shelter and woody substrates, which changes species composition and reduces species richness of liverworts and mosses in clear-cuts. Increased mechanical disturbance that removes remnant vegetation and exposes mineral soil may also play a role. In order to conserve bryophytes, we advocate mitigation of adverse ecological effects through enhanced environmental care within slash-harvested stands. Leaving more tree clusters, and creating and protecting large woody debris would be especially important in these stands, and would also improve the habitat for other organisms.

Slope Aspect Modifies Community Responses to Clear-Cutting in Boreal Forests

“…Mosses and liverworts may respond differently because most moss species are less shade adapted and drought sensitive than the majority of liverworts (Marschall and Proctor 2004). Hence, moss richness is less affected by exposure (Fenton et al 2003, Å stro¨m et al 2005, Hylander et al 2005. Furthermore, forest species, and species associated with convex substrates such as logs, stumps, and tree bases, are more prone to local extinction following clear-cutting .…”

Quantifying biodiversity impacts of climate change and bioenergy: the role of integrated global scenarios

“…If such necessary near future protected area expansions are not accounted for when considering restrictions to the allocation of bioenergy areas, the scenarios remain unrealistic, adding further challenges to the conservation of biodiversity. Moreover, further increases in the coverage of protected areas will be necessary to meet biodiversity targets, especially as the ranges of species are predicted to shift as a response to climate change (Araújo et al 2011;Hannah et al 2007;Hannah et al 2002;Heller and Zavaleta 2009). More generally, several studies recommend mainstreaming biodiversity conservation throughout land-use planning so that the landscape managed for economic purposes would remain biodiversity friendly (Hannah et al 2002;Noss 2001;Wilson and Piper, 2008).…”

Ecological Consequences of Increased Biomass Removal for Bioenergy from Boreal Forests

“…Reported effects of increased biomass removal on boreal forest vegetation differ (e.g. Åström et al, 2005;Olsson & Staaf, 1995). Fahey et al (1991) found that grass biomass increased more rapidly after WTH compared with SOH and continued to make up a higher proportion of the biomass during the first four years after harvesting, while Bergquist et al (1999) found no effects of WTH on grasses.…”