Profile

Mélissa Lauder
Master student
Department of Phytology
Laval University
melissa.lauder.1@ulaval.ca

Supervised by:

Line Rochefort (Regular member)

Research project description

Assessment of root biomass distribution in restored peatlands

Introduction: Peatlands alone store up to 30% of the carbon found in soils, making them crucial ecosystems in regulating the climate and fighting climate change. However, peatlands face significant anthropogenic pressures. In Canada, the peat industry extracts peat for its horticultural properties. A large proportion of these peatlands are being restored using an ecological restoration method that has proven its worth in sphagnum moss bogs. Models such as the CoupModel, developed by collaborators from McGill University, allow the coupling of soil, above-ground biomass, and atmospheric components to assess carbon fluxes in various ecosystems, such as restored peatlands. However, in the development of the model, no data on root biomass data is currently available for restored peatlands, even though such data exist for natural peatlands.Objectives: In this context, the study seeks to assess root biomass in restored peatlands. The primary objective is to assess the depth distribution of both fine and coarse roots in these restored ecosystems. The secondary goal is to identify abiotic factors (such as bulk density, water table level, and nutrient concentration) and biotic factors (including plant community) that will impact root biomass.Study sites: To achieve these objectives, data will be collected from 24 restored sectors of ombrotrophic peatlands distributed across Québec (mainly in Bas-Saint-Laurent and Lac-Saint-Jean) and New-Brunswick (mainly in the Acadian Peninsula). All of these sites have been restored using the moss layer transfer method (MTCM). In each province, four peatland sectors have been selected based on an average post-restoration age group (5, 10, or 20 years).Material and methods: For each sector, three-peat cores containing roots will be extracted. The cores will then be subdivided into four depth categories: neo-formed peat after restoration (0 cm and ), 0 to -20 cm beneath the neo-formed peat, -20 to -40 cm, and -40 to -60 cm. The root biomass collected from these samples will be sorted and dried at 70 °C until a constant weight is achieved, and then weighed to obtain biomass in g/cm2. In each sector, an additional core will be collected to obtain abiotic data that will be measured in the laboratory (bulk density, degree of humification, and concentration of chemical compounds) at all four depths. Additionally, a groundwater monitoring well will be installed to track the water fluctuations in the peatland. For biotic data, aiming to represent variations in plant communities, three vegetation surveys will be conducted in each sector by estimating the coverage of vascular and moss species in quadrats.Expected results: The data analyses will help confirm or refute the initial hypotheses. We anticipate observing a higher concentration of root biomass in the top 20 cm, with a positive correlation to the number of years post-restoration. This holds true irrespective of the residual depth of the peat. For the same restoration age, root biomass is expected to be greater with limited resources and challenging environment conditions (e.g., low water table, low-nutrient content, and high bulk density). These circumstances could encourage vegetation to produce more roots to extract necessary nutrients from an unproductive environment. Lastly, it is assumed that root biomass will be higher in a plant communities dominated by ericaceous species compared to graminoid species.

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