PARENT SESSION
Poster Session 2: Forest Ecology
Monday, August 8, 5:00 PM - 6:30 PM, Exhibit Hall 220 A-E, Level 2, Palais des congrès de Montréal

Bryophytes as indicators of paludification after partial harvest in the eastern boreal forest.

Fenton, Nicole^*,1, Bergeron, Yves ¹, ¹ Université du Québec en Abitibi-Témiscamingue, Rouyn-Noranda, Québec, Canada

ABSTRACT- In eastern Canada, boreal forests develop structural diversity in association with time since stand replacing fire. In some regions, including the Clay Belt of Québec and Ontario, this is associated with significant changes in the bryophyte community (Sphagnum moss invasion) and paludification (thick waterlogged forest floor development). Within a forest management context, structural diversity is not maintained by clear-cut systems, which only regenerate even-age stands. Partial harvest systems have been proposed as a strategy to maintain structural diversity, however it is unknown whether these interventions will accelerate paludification and result in the creation of unproductive peatland stands. In order to assess this possibility, bryophytes were used as indicators of paludification. Bryophyte community evolution across a paludification chronosequence was documented, and subsequently changes in the bryophyte community after partial harvest were compared to changes after clear-cut and to natural evolution of the community. The bryophyte community responded to opening of the forest canopy, particularly by expansion of slow growing Sphagnum capillifolium that had established in the closed stands. The subsequent expansion, and development of a moist forest floor via water table movement, ultimately allowed the invasion of faster growing Sphagnum spp. (e.g. magellacanum, fallax) that are dependent on constant hydration. Ultimately, with increasing height above water table and available light, S. fuscum. After harvest, Sphagnum patch size was reduced by -19.8% in the clear-cuts compared to -11.7% after partial harvest. While trends were not constant across three separate partial cut trials, the proportion of Sphagnum magellacanum, fallax and fuscum increased compared to controls and clear cuts. This may indicate that partial harvests effectively shift the bryophyte community towards an older community type and from a production perspective, may limit the capacity of these partially harvested sites to produce merchantable timber.

Key words: bryophytes, indicators, paludification, boreal forest management