NWT RESEARCH DATABASE

Tags: permafrost, vegetation, soil chemistry

Objective(s): To quantify the relationships between vegetation community composition, structure and near-surface ground ice content.

Project Description: The primary objective is to quantify the relationships between vegetation community composition, structure and near-surface ground ice content. An improved understanding of ground ice-vegetation interactions allows a better understanding of permafrost ecosystems the ability to more easily measure near surface ground ice conditions. Around Yellowknife there is a patchwork of bedrock outcrops separating forest stands with many types of vegetation. Mature vegetation includes deciduous forest cover of white birch, mixed stands, and white spruce and/or black spruce dominated forests. Sampling will be conducted across these different vegetation types to ensure that the range captured. Within each discrete forest stand, vegetation plots will be established to determine community composition and structure. To determine forest characteristics, 400 meter squared plots will be set and woody vegetation with diameter of 5 cm or greater will be measured using standard sample plot protocols. Four 1 meter square ground vegetation plots will be set next to tree plots and the identity and abundance of all vegetation more than 2 meters high determined. At each vegetation plot, the organic layer thickness and the thickness of the active (seasonally thawed) layer will be measured. Soil sampling will consist of taking shallow soil cores (3 per site) from the active layer and top 50 cm of permafrost using a 2-person, hand-held auger. Core logging in the field will include visual estimates of ice content and sample length. Soil physical and chemical properties will be studied back in the laboratory in Yellowknife. The following will be measures: dry bulk density; water and ice content; soil organic carbon; and soil salinity (conductivity, major ions, pH). These measurements will allow for researchers to study the relationship between plant community composition and ground ice content. All theses, publications, and presentations arising from this work will be shared with communities and government and a plain language document given to communicate the result to community members unable to participate in public presentations. At project completion, the team will provide an update of the research in Yellowknife and, if possible, in Behchoko to communicate the findings to the community. The fieldwork for this study will be conducted from April 15, 2015 to August 31, 2015.