The initial biometerology of the constructed Sandhill Fen Watershed in Alberta, Canada

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Creator: 

Clark, Matthew Graham

Date: 

2018

Abstract: 

Resource extraction has led to the loss of boreal landscapes. Recently, novel integrated landscapes have been constructed to return ecological functions lost due to disturbance. The Sandhill Fen Watershed (SFW) is one of the first of two such projects in the boreal plains ecozone. The SFW is a mix of upland, midland and lowland topographical features designed to develop into integrated boreal plains ecosystems. This thesis quantifies the initial carbon cycling dynamics within the SFW and contextualizes this development with studies on conventional reclamation projects and undisturbed ecosystems.

Construction, vegetation seeding and planting of the SFW was mostly completed by 2012, and an initial wetting occurred in 2013. Methane fluxes remained low over the first three years. However, mobile ions of sulphur declined over this same period and could indicate shifting reduction-oxidation conditions favourable for future rates of methanogenesis. In the lowland, biogeochemical fluxes were indicative of highly reduced soil conditions. This was confirmed in 2015 with reduction-oxidation potential monitoring. Downscaled eddy covariance flux measurements showed that vegetation increased evapotranspiration (ET) rates in the lowland relative to non-vegetated water surfaces. Since there were no other substantial outflows of water from the SFW, greater rates of ET may lower the water table in the future and limit the carbon storage potential of the ecosystem through peat accumulation. Measurements of the CO2 exchange between the surface and the atmosphere showed that, with no other substantial carbon outputs, by its third year the SFW lowland had become a net carbon sink and had daily, monthly, and annual carbon cycling behaviour similar to undisturbed boreal wetlands. Net sequestration of CO2 in the lowland occurred because the design of the SFW promoted saturated anoxic conditions which suppressed soil respiration while also promoting hydrophytic vegetation productivity. Since past efforts to restore degraded wetlands have not always succeeded in recreating carbon cycling functions similar to those of undisturbed wetlands, the SFW may be an effective approach to achieve post-mining landscape closure.

Subject: 

Physical Geography
Atmospheric Sciences
Biogeochemistry

Language: 

English

Publisher: 

Carleton University

Thesis Degree Name: 

Doctor of Philosophy: 
Ph.D.

Thesis Degree Level: 

Doctoral

Thesis Degree Discipline: 

Geography

Parent Collection: 

Theses and Dissertations

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