Laura Hjartarson
Master student
Department of Biology
Laval University

Supervised by:

Juan Carlos Villarreal (Regular member)

Co-supervised by:

Line Rochefort (Regular member)

Research project description

Characterization and function of biological soil crusts post-disturbance in Quebec’s boreal forest

Introduction: Biological soil crusts (BSC) are communities of bryophytes, lichens, cyanobacteria and other microbes that bind together with soil particles to form a surface crust. BSC have been widely recognized in supporting ecosystem functions such as soil formation and stabilization, alteration of hydrology, and fixation of atmospheric carbon and nitrogen. BSC are well studied in arid regions, however little attention has been given to their study in the boreal forest. While not dominating the boreal landscape, BSC can form extensive communities on disturbed sites such as abandoned roads, mines, and borrow pits. In their initial state, these sites can lack soil stability and are highly susceptible to erosion. BSC can serve to stabilize the soil and make it more hospitable for other organisms. As well, the bacterial communities associated with BSC are less studied compared to their macro counterparts. Bacteria play an important role in improving soil structure and catalyzing primary succession. Objectives: This project aims to: characterize the species of BSC spontaneously establishing on borrow pits and mines; to identify the main environmental factors governing the distribution of these BSC communities; to characterize the bacterial communities associated with BSC establishing spontaneously on an abandoned mine and their associated nitrogen fixing capabilities. Study sites: Abandoned borrow pits will be studied in Parc national des Grands-Jardins, located in the Charlevoix region in eastern Québec and along La Route du Nord, a gravel road linking the town of Chibougamau to the James Bay region. An abandoned mine will be studied in the Abitibi-Témiscamingue region of western Québec. Material and methods: Surveys of the BSC species establishing on borrow pits will be conducted in using 25 cm x 25 cm quadrats within 100 m2 plots. The slope, aspect, thickness of the crust and presence of frost heaving will be recorded. A composite soil sample will be taken at each plot for physicochemical analyses. 16S rDNA sequence analysis will be used to assess the bacterial communities of different types BSC that have developed on abandoned and restored mines. In addition, nifH gene sequencing will be used to assess the presence of diazotrophic species. Expected results: This project will help to fill an important gap in the knowledge of boreal BSC. By understanding what species are present, their community composition, and their associated abiotic variables, we will be better able to understand what role their characteristics play in natural successional processes. Our assessment of their role in nitrogen fixation in recovering disturbed boreal sites will further our understanding of the functional traits of these BSC. Additionally, the research project will formulate preliminary recommendations in terms of testing restoration techniques imitating natural successional processes for northern mines.

Research Site Coordinates

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