Facteurs environnementaux influençant la biodiversité des lichens à différentes échelles dans le nord-ouest du Québec

Northwestern Quebec currently has a relatively small human population, few human impacts, and fewer studies on lichen diversity. However, further development in mining, hydroelectric, and tourism is planned for the future. This poses several problems: 1) as we have little information about what lichen species are present and which habitats are important to them, it is difficult for resource managers to mitigate diversity and habitat loss during project development; and 2) it may be difficult to mitigate impacts to habitats without a good understanding of environmental factors, like humidity, that influence lichen diversity. Therefore, this project seeks to study lichen diversity and certain environmental factors that affect that diversity in three different habitats following Leboeuf et al (2012)’s definitions – Uniform Bogs, Spruce Bogs, and Uniform Fens – that cover a large part of the northwestern Quebec region. To do this, we consider lichen diversity on three different scales, here defined as: alpha, changes in lichen diversity between microhabitats; beta, changes in lichen diversity between peatland types; and gamma, differences in lichen diversity between sectors of the study region. To meet this aim, three study sectors placed relatively equidistantly along a 600 km transect in the Eeyou Istchee Region were selected. The transect covered both north-south and east-west gradients. The sectors were centered around three mines – Casa Berardi, Whabouchi, and Renard – though we avoided peatlands that likely had impacts from mining, as this was not the aim of our study. Three replicates each of Uniform Bogs, Spruce Bogs, and Uniform Fens were chosen at each site. In each replicate, two 20 meter transects were set up, one running north-south from a central point and the other running from a randomly selected edge point towards the central point. Lichen specimens and a lichen abundance measure were collected on microhabitats within one meter of either side of the transect line. A sensor for relative air humidity and temperature was placed at the center of each transect line, where a canopy opening reading was also taken. To reduce the likelihood of missing species diversity, a one-hour Floristic Habitat Sampling (FHS) protocol was followed. In the FHS method, microhabitats and areas not covered by the transects were targeted and searched for species not yet collected. All lichen samples were identified to species in the laboratory, using chemical spot tests as necessary. Particularly difficult or important specimens will be confirmed with Thin Layer Chromatography (TLC). Mixed linear models and linear regressions on species richness and abundance were run in R software. Seventy-six lichen species were documented in this study, and trees and saplings were the most lichen rich microhabitats. On the alpha scale, peat and snags, while less lichen diverse individually, were associated with large and unique pools of lichen species. On a beta scale, Unique Fens were less lichen diverse than Uniform Bogs or Spruce Bogs. Since both peat and snags were found less frequently in Uniform Fens, we hypothesize that the lower diversity in Uniform Fens is due in large part to the low availability of these two microhabitats. Microhabitat availability was also key to the significantly higher lichen diversity at the northernmost site. In this case it was rocks, largely absent at all other sites, that were of the greatest importance. Gamma scale lichen diversity also increased from the south to the north with several species only found in the most northern site, a pattern reflected in increasing relative air humidity and lower overall temperatures. We hypothesize that these trends in gamma lichen diversity and environmental factors are linked, though exactly how temperature influences or interacts with other environmental factors is unclear. These results will aid resource managers to mitigate biodiversity loss of lichen species by informing decisions as to which peatland habitats are of higher importance for lichen conservation.