Do forests treated by partial cutting provide growth conditions similar to old-growth forests for epiphytic lichens?

Published in Biological Conservation 159: 458-467. https://doi.org/10.1016/j.biocon.2012.12.019

In boreal forests, partial cutting is increasingly proposed as a suitable alternative to the widespread use of clearcutting in order to conciliate forest management with habitat conservation for epiphytic species. We compared the growth of two epiphytic lichen species, Bryoria nadvornikiana and Evernia mesomorpha, in old forest stands recently treated by partial cutting and untreated controls, located in black spruce boreal forests of western Québec. Lichen growth rates were measured over a period of tow years from transplants of the two species, and several environmental variables (e.g., canopy openness, thallus temperature, and tallus wetness) were also measured directly at the sampling sites. Despite important within-treatment variation in growth rates among transplants, we observed reduced growth rates in partial cuts for both species. Canopy openness measurements of more than 40% resulted in negative growth rates for B. nadvornikiana, a species typically associated with relatively closed canopies, and canopy openness over 70% resulted in negative growth rates for E. mesomorpha, a species that tends to be associated with open canopies. This negative growth response contrasts with what is generally reported in the literature about the effect of canopy opening creation on epiphytic lichen growth. As a function of the environmental parameters that were measured on site, we suggest that a reduction in the duration of hydration periods, and an increased risk of thallus fragmentation in partially cut stands, especially for B. nadvornikiana, could explain this result. Because this negative effect could be more likely to occur during dry periods, future trends in the response of epiphytic lichens to the creation of canopy openings could be influenced by climate change. This study suggest that even if partial cuts can be a good alternative to clearcutting for the conservation of epiphytic lichen species, they are more likely to succeed if dense clumps of residual trees (canopy cover > 70%) are retained in the treated stands.

Forests

Scientific Article

Forest Ecology, Forestry Research, Forests

Bouchard, Mathieu

BOUDREAULT, Catherine, Darwyn COXSON, Yves BERGERON, Susan STEVENSON and Mathieu BOUCHARD

2013

Paper

Available at the Direction de la recherche forestière

forêt boréale, coupe partielle, lichen épiphyte, écologie forestière, flore et espèces menacées, article scientifique de recherche forestière, forest ecology, boreal forest, bryoria nadvornikiana, epiphytic lichen conservation, epiphytic lichen growth, evernia mesomorpha, lichen transplants, partial cutting, sping gray horsehair lichen