Shrub canopy induces a decline in lichen abundance and diversity in Nunavik (Québec, Canada)

ABSTRACT

Lichens are an important component of biodiversity in northern ecosystems and are involved in diverse ecological processes. They contribute to nutrient availability through nitrogen fixation, are a substantial part of caribou winter diet, and influence global climate by increasing land surface albedo. Over the last decades, increased primary productivity in northern ecosystems, mainly associated with the expansion of shrub species, has led to a decline of lichen-dominated areas. We evaluated the impacts of shrubs on lichens by comparing lichen communities in the open environment and underneath dwarf birch (Betula glandulosa) canopy in Nunavik, Canada. Our results showed a decrease in abundance, richness and evenness and a shift in community composition between open areas and understory. These changes were mainly induced by the presence of a shrub canopy rather than by its characteristics, because shrub height and canopy closure had little effect. Richness and evenness dropped from shrub edge to shrub center, suggesting that the intensity of the decline was positively correlated to the time spent under the shrub canopy. Important changes in lichen communities are therefore expected to occur with further shrub expansion and may have substantial unfavorable implications for global climate and ecosystem functioning.

KEYWORDS:

• Climate change
• lichens
• northern ecosystems
• shrub expansion

Acknowledgments

We thank Denis Sarrazin, Julien Lebrun, and Sidney Arruda (CEN) for helping us with the logistics of the field campaign; Rachel Guindon, Claudia Beaupré, and Audrey-Anne Grenier for their assistance in the field; Claude Roy and Jean Gagnon for sharing their expertise with lichen identification; Juan Carlos Villarreal Aguilar for his comments on a previous version; and Émilie Saulnier-Talbot for English revision.

Disclosure statement

No potential conflict of interest was reported by the authors.

Additional information

Funding

This work was funded by the Ministère des Forêts, de la Faune et des Parcs (MFFP) of the government of Québec, the National Science and Engineering Research Council (NSERC) of Canada, the Centres d’études nordiques (CEN), and Northern Scientific Training Program (NSTP).