Restauration des gradients éco-hydrologiques dans les écotones artificiels en périphérie des tourbières post-extraction

Authors: Lefebvre-Ruel, Stéphanie
Advisor: Jutras, SylvainRochefort, Line
Abstract: Now that optimal restoration methods of cutover peatlands are known and applied, it becomes relevant to study the sharp ecotones left at the edge of these sites. This project aimed to characterize the eco-hydrological gradients of these artificial ecotones and to test restoration actions to reduce the eco-hydrological differences between these and reference ecotones. The topography, the hydrology and the vegetation have been characterized along transects extending into these ecotones in one cutover fen and two cutover bogs (Quebec and Alberta). Our results show sharp changes in the elevation of the soil surface and groundwater table, with height differences in soil surface up to 119 cm in the first meter next to the ditch and goundwater table as deep as 65 cm below the surface in the first four meters near the ditch. Tree density up to 24 000 stems/ha compared to a maximum of 2 000 stems/ha in the reference ecotones has been found along the edge in the first meters next to the ditch resulting in mosses coverage much lower than in reference ecotones. Thus, the impacts of horticultural peat extraction activities are important at one meter next to the contour ditch into the adjacent peatland, still present at 8 m and absent at 25 m. To reduce those eco-hydrological disturbances, restoration actions consisting in tree cutting, complete ditch filling and gradual leveling of the soil surface have been tested along the edge of the artificial ecotones. The topography and groundwater table in the managed ecotones showed more progressive gradients which suggests the return of eco-hydrological conditions that will favour a transition similar to the reference ecotones. On the basis of those results, we suggest integrating these steps to restore artificial ecotones as a regular action of restoration processes intended for post-extraction peatlands.
Document Type: Mémoire de maîtrise
Issue Date: 2016
Open Access Date: 24 April 2018
Grantor: Université Laval
Collection:Thèses et mémoires

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