Boreal ecosystem changes due to permafrost thaw across the discontinuous to sporadic permafrost zone

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dc.contributor.authorFlade, Linda
dc.contributor.authorUniversity of Lethbridge. Faculty of Arts and Science
dc.contributor.supervisorChasmer, Laura
dc.contributor.supervisorHopkinson, Christopher
dc.date.accessioned2025-02-12T20:52:50Z
dc.date.available2025-02-12T20:52:50Z
dc.date.issued2024
dc.degree.levelPh.D
dc.description.abstractThis PhD thesis developed a framework to model, quantify, and improve understanding of spatially explicit changes in short-to-tall-stature vegetation structure in the southern Taiga of northwestern Canada. This region is still changing due to the retreat of the Laurentide Ice Sheet since the last glacial maximum (~22.1 cal ka BP). In addition, climate change has caused rapid ecosystem changes, for example due to permafrost thaw, with implications to carbon sink strength and wildland fire susceptibility, amongst others. Regional allometric equations for shrubs and short-stature trees were developed to estimate aboveground biomass (AGB) and live aboveground plant carbon stocks using 1D, 2D, and 3D field measurements. Spatially coincident bi-temporal airborne lidar data were used to develop a single AGB model applicable across changing relationships between lidar point clouds and AGB magnitudes as ecosystems change form, ecosystem boundaries expand and recede, and airborne lidar technologies evolve. By fusing field data with bi-temporal airborne lidar data, the study quantified and analyzed changes in vegetation structure and aboveground plant carbon stocks. By employing geospatial statistical analysis and machine learning the underlying important drivers of these changes were identified. Key findings of this thesis were the following: (1) the developed framework has improved understanding of the magnitudes and directions of short-to-tall-stature vegetation structural changes over the past decade (2010 to 2019); (2) increases in the growth and abundance of short-stature vegetation were substantial across the study region and need to be integrated into carbon accounting frameworks with extension to unmanaged forest and peatland ecosystems. Overall, the established framework could aid in the modelling of wildland fire fuel dynamics and fire behavior also in peatlands, which could reduce community risk to fire in this region.
dc.description.sponsorshipThis project was funded in part by NSERC Discovery Grants to L. Chasmer [Grant number: (2017-04492)] and C. Hopkinson [Grant number: (2017-04362)], a University of Lethbridge start up grant to L. Chasmer, the NSERC Canada Wildfire Network (Chasmer) [Grant number: RES0049086], a CFI grant for field survey equipment to C. Hopkinson [Grant number: (32436)], and a grant to purchase the Titan lidar system through Western Economic Diversification Canada [Grant number: (000015316)].
dc.embargoNo
dc.identifier.urihttps://hdl.handle.net/10133/6975
dc.language.isoen
dc.publisherLethbridge, Alta. : University of Lethbridge, Dept. of Geography and Environment
dc.publisher.departmentDepartment of Geography and Environment
dc.publisher.facultyArts and Science
dc.relation.ispartofseriesThesis (University of Lethbridge. Faculty of Arts and Science)
dc.subjectclimate change
dc.subjecttaiga
dc.subjectairborne lidar
dc.subjectallometric equations
dc.subjectaboveground biomass
dc.subjectcarbon
dc.subjectvegetation structure
dc.subjectremote sensing
dc.subject3-dimensional
dc.subjectupland forests
dc.subjectpermafrost plateaus
dc.subjectbogs
dc.subjectfens
dc.subjectecotones
dc.subjectvegetation mensuration
dc.subjectshrubbification
dc.subjecttree mortality
dc.subjectbaseline
dc.subjectchange detection
dc.subjectcarbon accounting
dc.subjectfuels
dc.subject.lcshDissertations, Academic
dc.subject.lcshClimate change--Canada, Northwestern
dc.subject.lcshTaigas--Canada, Northwestern--Remote sensing
dc.subject.lcshOptical radar
dc.subject.lcshBiomass--Canada, Northwestern--Measurement
dc.subject.lcshVegetation surveys--Canada, Northwestern
dc.subject.lcshEcological surveys--Canada, Northwestern
dc.subject.lcshPermafrost forest ecology--Canada, Northwestern--Remote sensing
dc.subject.lcshVegetation monitoring--Canada, Northwestern--Remote sensing
dc.titleBoreal ecosystem changes due to permafrost thaw across the discontinuous to sporadic permafrost zone
dc.typeThesis
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