Examining Aspen Expansion from Before and After Prescribed Burning in a Native Fescue Grassland Through Geospatial Techniques

• Main Author: Anderson, Christopher L
• Format: Thesis
• Language: English
• Published: Michigan Technological University 2019
• Subjects: Ecology; Canada; Canis lupus; Bison bison bison
• Online Access: http://pqdtopen.proquest.com/#viewpdf?dispub=13900181

Native fescue (Fescue spp.) grasslands of the Intermountain West have become increasingly scarce due to the advent of modern agriculture, the loss of Indigenous people’s land management practices, modern wildfire management and the extirpation of bison (Bison bison bison). Native grassland is a biodiversity hot-spot, is significant for carbon sequestration, and essential to many species of flora and fauna that occur in the ecosystem. Our study site, on the Rocky Mountain Front in Waterton Lakes National Park, Alberta Canada, consists of 30 discrete aspen stands (Populous tremuloides) which are encroaching on this declining shortgrass fescue grassland. Parks Canada is attempting to suppress aspen expansion and improve fescue prairie through ecological restoration by instituting prescribed burns and elk (Cervus elaphus) browse. Prescribed burns will decrease woody vegetation through adult aspen stem mortality while stimulating regeneration, which is subsequently browsed by elk. The park has a wolf pack (Canis lupus) that preys primarily on the elk, thereby affecting aspen stem recruitment spatially. These dynamics create a natural laboratory for examining the interaction of fire, elk and wolves that impact the aspen/grassland dynamics. We measured the aspen stand structure before and after a prescribed burn set in spring of 2017 to determine the change in aspen stand area from before to after the burn. We measured aspen stands before the prescribed burn during the summer of 2016 via GNSS handheld mapping units. We collected post-burn measurements in summer 2017 via unmanned aerial system (UAS). We also conducted ground measurements for a subset of aspen stands in 2017 to ground-truth the aerial photography data. We used knowledge Engineer (KE) in Erdas Imagine for classifying the UAS imagery and then created polygons in ArcGIS to analyze the data from before and after prescribed burning. We also digitized all aspen stand layers from the UAS imagery through the heads-up digitization technique and used these data to compare the aspen stands from before to after prescribed burning. Aspen stand area did not decline at a statistically significant level for any layers we measured: canopy, regeneration, and shrub expansion before and after prescribed burning. We did see an observational decline in the total aspen canopy area.