Page 148 - PC2019 Program & Proceedings

PLANT CANADA 2019

S81. Fourteen-year impacts of partial and total forest harvest on epixylic bryophyte species in
boreal black spruce –feathermoss forests
*1
1
Opoku-Nyame, J. ; A. Leduc ; N. Fenton
2
1 Université du Québec en Abitibi-Témiscamingue (UQAT)
2 University of Quebec in Montreal
Partial cut harvest has been hypothesized to have a lower impact on forest vegetation and to encourage
old growth species assemblages compared to clear cut harvest. Fourteen years after harvest, we used
epixylic bryophytes as indicator species to assess partial cut efficacy to attenuate harvest impacts on
forest vegetation in the boreal black spruce forest of Quebec.We examined changes in the epixylic
bryophyte community and their microhabitat in 30 permanent plots along an unharvested, partial cut and
clear cut harvest gradient. Also, we compared our results to that of an initial post-harvest study to
examine species changes overtime. The results showed that, epixylic species richness and composition
were mainly influenced by canopy openness, deadwood decay and diameter size. Partial cut stands
recorded a richer epixylic community compared to unharvested and clear cut stands. Species richness and
frequency of occurrence doubled in partial and clear cut stands overtime compared to the initial study.
Additionally, conditions in partial cut stands supported drought sensitive and old growth confined species
which are threatened by conditions in clear cut stands. In conclusion, partial cut harvest provides a better
option in achieving species and habitat conservation goals than clear cut harvest. However, deadwood
input should be considered in implementation strategies to ensure continual persistence of epixylic
bryophytes and deadwood living organisms in general.

Jeffrey Opoku-Nyame (jeffrey.opokunyame@uqat.ca)

S82. Modelling successional dynamics of Canadian boreal mixed woods prior to and following the
Spruce Budworm outbreak
1
*1
1
Maleki, K. ; M. Gueye ; B. Lafleur ; A. Leduc ; Y. Bergeron
1
2
1 University of Quebec in Abitibi-Temiscamingue (UQAT)
2
University of Quebec in Montreal
Forest simulators provide better understanding and predicting of the forest response to different
silvicultural treatments or environmental stresses. Applying SORTIE-ND, we modelled short- and long-
term successional dynamics in the boreal mixedwoods of eastern Canada. We used 431 quadrats
(16×16m), distributed in seven stands originating from different fires (1760-1944) and representing a
chronosequence of post-disturbance stand development. In each quadrat, all trees, including seedling,
saplings and adults were sampled in both 1991 and 2009. Using the 1991 data, we calibrated SORTIE-
ND through 18-year simulations to reconstruct the empirical data collected in 2009, in terms of stand
composition and structure. When the model successfully parametrized, over long-term (100-year)
simulations, we tested whether simulating young stands to reach to older ages resulted in structure and
composition similar to those seen in old-growth stands. We also verified the influence of spruce budworm
outbreak on post-fire stands by simulating stands prior to and following the outbreak. Results showed that
due to possible differences in stand composition following wildfires and in stand disturbance histories,
SORTIE-ND could not precisely estimate species dominance of old-growth stands, though it provided a
decent estimation of species composition and diameter distribution of old-growth mixedwoods.
Moreover, long-term simulations revealed that despite the impacts of the most recent spruce budworm
outbreak on species dominance, in long term, forest composition turned to be similar for disturbed and
undisturbed stands.

Kobra Maleki (kobimmm1359@gmail.com)

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