Using the past to inform the future: A paleoecological perspective of the impacts of drought and fire on lakes, permafrost and forests

Regions: Dehcho Region, North Slave Region, South Slave Region

Tags: physical sciences, water quality, permafrost, wildfire, drought

Principal Investigator: Pisaric, Michael FJ (18)
Licence Number: 16609
Organization: Department of Geography, Brock University
Licensed Year(s): 2019 2018 2017 2016
Issued: Aug 08, 2019
Project Team: Dr. Kevin Turner; Dr. Katrina Moser; Dr. Steven Kokelj; Caitlin Garner; Dana Harris; Krista Chin

Objective(s): To examine the frequency and severity of past wildfire and drought (drought-like) conditions in the southern Northwest Territories.

Project Description: This licence has been issued for the scientific research application No.4564.

The objectives of this research are to examine the frequency and severity of past wildfire and drought (drought-like) conditions in the southern Northwest Territories. Specifically, the research team will examine the following questions: 1) how frequent and severe have fires been in the; 2) are fires becoming more frequent/severe due to the impacts of climate change; 3) what impact does wildfire have on water quality in streams and small lakes impacted by severe fires in 2014/2015; 4) how frequent and severe has drought or drought-like conditions been in the North Slave region in the; 5) are the recent drought-like conditions experienced in 2014/2015 in the North Slave region anomalous in the context of the past 2-3 centuries or even thousands of?

The lake sediment sampling will occur during the late winter/early spring season and during mid-summer each year. The late winter/early spring field work will occur while the lakes are still ice covered. The research team will target small lakes to recover long sediment records spanning most of the Holocene (past 10,000 years). The team anticipate these cores to range in length from 1.5 - 3.0 m. Using the ice cover as the coring platform the team will use a Livingstone piston corer to recover longer sediment profiles from these lakes. The piston coring system allows the team to collect several metres of sediment from lakes with depths varying from a few metres to 10-15 metres. A g as powered ice auger to cut through the ice cover and will carry a spill clean up kit with us at all times. These cores will be examined for their sub-fossil diatom assemblages, charcoal and oxygen and carbon isotopes. Surface sediment cores from the bottom of each lake will also be obtained. A Glew gravity coring system will be used to recover undisturbed sediment profiles from the lake bottom. At each lake the team will also collect water samples to analyze for water chemistry. 10-15 lakes will be sampled. The team will target lakes that have recently experienced forest fires or those that have burned in the past 50 years or so. These known fire events can be used to confirm that lake sediment charcoal records do in fact capture local wildfire events.

This research will also focus on the examination of tree growth at several sites in the Snare and Yellowknife river basins. Sites will be visited in the Snare and Yellowknife River systems to develop long tree ring records for these regions. At each site, approximately 30-50 trees will be sampled. A small core (~4.3 mm in diameter) is removed from each tree. If dead snags or old logs are present on the ground, a 1-inch thick cookie will be cut from these samples. In the case of dead standing snags the team will not disturb trees that appear to be nesting sites for any birds. The team anticipates visiting approximately 15-30 sites in each river basin during the tenure of this research licence.

For the team to determine the impacts of wildfires on stream health, they will sample assemblages of macroinvertebrate populations living in small streams that were impacted by fires in 2014 and 2015. Stream macroinvertebrates are bugs that live in water, have no backbone and can be seen with the naked eye. The team will target several streams (Baker, Boundary, Mosquito Creeks and others along Highway Three within the Mackenzie Bison Sanctuary) to sample stream benthic macroinvertebrate communities and water chemistry. Two types of stream systems that will be sampled are: 1) those that were directly impacted by wildfires in summer 2014 and 2015, and 2) control systems that have not experienced recent wildfire activity. We will follow standard Canadian Aquatic Biomonitoring Network (CABIN) protocols for sampling macroinvertebrate communities. Samples will then be screened to remove large pieces of organic material and to separate macroinvertebrates. Macroinvertebrates will be preserved and then identified using various identification books and materials supplied by the CABIN. A number of species diversity indices will be calculated to enable comparisons between impacted and non-impacted stream systems.

Water samples will be taken to examine changes in water chemistry between impacted and non-impacted stream systems, including measurements of nutrients, metals, conductivity and DOC (dissolved organic carbon). A YSI multiparameter sonde will be taken into the field with us to measure stream pH, salinity, DO (dissolved oxygen) and temperature. Water chemistry data will be analysed using multivariate statistics.

To communicate the research results to the nearby communities, the team will submit all theses and publications to the library at the Aurora Research Institute. The research team will also communicate the results via northern meetings such as the Geoscience Forum and the Cumulative Impacts Monitoring Program Results Workshop. The research team are happy to give community presentations in any of the local communities while in town. Additionally, the team are happy to work with school children or college students to teach them more about the work.

The fieldwork for this study will be conducted from June 1, 2019 to September 30, 2019.