Land-use change is prevalent across the Prairie Pothole Region (PPR) because of widespread
agricultural expansion over the last century. Different land-use histories will affect the distributions of
native vegetation and soil biogeochemistry of PPR wetlands. Furthermore, because native vegetation is
partially required for wetland classification, supplementary methods are needed for proper wetland
delineation. Accurate estimates of GHG emissions are required for correct climate change models;
therefore proper investigation of contrasting land-use histories on GHG emissions is essential. This
study focused on determining the effect that different land-use histories had on the expression of soil
hydric features and magnetic susceptibility as well as examining interacting effects among contrasting
land-use histories and biogeochemical controls of GHG emissions of PPR wetlands.
To determine the differing effects of land-use histories on hydric soil indicators and magnetic
susceptibility, fifteen ephemeral wetlands under differing land-uses (annually cultivated, restored
grassland, seeded pasture and native grassland) were sampled to a depth of 1 m with samples collected
every 10 cm. An upland pit was correspondingly sampled for each wetland. Soils were then analyzed
for organic C, inorganic C, dithionite extractable Fe, particle size distributions, wet stable aggregate
distributions and magnetic susceptibility at four different temperature treatments (room temperature,
100 °C, 300 °C and 500 °C). While some variables had observable difference among the land-uses (i.e.
organic C, dithionite extractable Fe and magnetic susceptibility), the most pronounced differences were
between the different pit positions (i.e. wetland pits vs. upland pits). The data was holistically analyzed
through non-metric multidimensional scaling (NMDS) and position based differences were easily
identified through this approach; however, only slight differences were present with respect to
contrasting land-use histories.
The controls of GHG emissions and their interactions were evaluated through two laboratory
incubations (i.e. CH4 incubation and N2O incubation), with a factorial design using land-use history
treatments as well as biogeochemical controls specific to each GHG (i.e. CH4: SO4- additions; N2O: water
filled pore space [WFPS] treatments and NO3
- additions). Both incubations had the presence of
interacting factors among the differing land-use histories. During the CH4 incubation, each land-use
history responded oppositely to sulfate additions. During the N2O incubations, both WFPS treatments
and NO3
- additions had additive effects on the emissions of N2O. Moreover, the presence of the
interactions satisfied the objective of the incubation study.
Overall it was determined that while land-use history significantly altered the response of GHG
controls with respect to GHG emissions, it did not have strong effects in influencing hydric soil indicators
and magnetic susceptibility values.
| Identifer | oai:union.ndltd.org:USASK/oai:ecommons.usask.ca:10388/ETD-2013-04-1026 |
| Date | 2013 April 1900 |
| Contributors | Bedard-Haughn, Angela K. |
| Source Sets | University of Saskatchewan Library |
| Language | English |
| Detected Language | English |
| Type | text, thesis |
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