|Thursday, July 08|
Mélanie is a plant ecologist with a strong interest for bryophyte communities in temperate to subarctic ecosystems, especially in ecotones. Her research aims to understand the factors controlling the assembly of moss communities and their microbiota, as well as their ecosystem functions (carbon and nitrogen cycles). She uses a variety of ecological, biogeochemical, and molecular approaches to address the roles and diversity of bryophyte communities under changing climate and disturbance regimes using field-based observational and experimental studies.
Disturbance, growth, succession and nitrogen fixation in the boreal forest: a bryophyte perspective
* Mélanie Jean, Université de Moncton, Canada
Bryophytes dominate the forest floor, regulate soil microclimate, and participate in the carbon (C) and nitrogen (N) cycles in coniferous boreal forests. The bryosphere represents the network of associations between microorganisms and invertebrates living on the leaves, stems, and decaying parts of bryophytes. Associations between mosses and diazotrophs (N-fixing microorganisms) are increasingly recognized as an important N source in northern and temperate ecosystems. In this presentation, I explore how canopy type (coniferous vs. broadleaf deciduous), environmental conditions, and time since fire, affect moss succession, growth, and associated N2-fixation in North American boreal forests. Results support the hypothesis that leaf litter deposition exerts a strong control on moss assemblages, abundance, and growth rates in the boreal forest. In the absence of leaf litter mosses grow better and present higher rates of associated N-fixation in coniferous than deciduous forests and experimental leaf additions negatively affect these processes in both forest types. The moss microbiome, N-fixation rates, and potential contributions to stand-level N cycling depend on the moss host species, forest type, and geographical location. Global changes in disturbance regimes, forest composition and climate can therefore have profound impacts on moss communities that may alter the structure and composition of the boreal forest.