Groundwater and vegetation influences on alpine wetland evapotranspiration

Abstract

Wetlands are increasingly recognized for their ecological significance and hydrological function, particularly in snowmelt-dominated mountain regions experiencing climate change. This thesis investigates evapotranspiration (ET) and groundwater-surface water interactions within the Burstall Wetland, a mineral wetland located on the eastern slopes of the Canadian Rockies. The study aims to (1) examine seasonal wetland-scale ET fluxes and the relative contribution of snowmelt versus growing-season processes, and (2) identify the sub-surface and vegetation controls on spatial ET variability during the snow-free period. Data collection was conducted during the 2022 growing season using eddy covariance (EC) to measure wetland-scale energy and carbon fluxes and a closed dynamic chamber system to capture microsite ET across dominant vegetation communities (sedge, willow, moss, and litter). Groundwater levels were monitored through a network of groundwater wells, and volumetric water content (VWC), soil temperature, and meteorological variables were recorded to support ET estimation and spatial analysis. By integrating site-scale flux observations with chamber-based measurements, this study characterizes the spatial heterogeneity of ET and evaluates the contribution of groundwater to seasonal loss. The findings provide insight into the ecohydrological processes governing alpine wetland function and offer a baseline for assessing wetland sensitivity to future climatic and hydrological shifts in mountain environments.