The resource link will access Part 1 of this presentation. Part 2 can be accessed here.
Where do you look for evidence of fires that burned thousands of years ago? In the bottom of a lake. Dr. Michael Pisaric describes how coring lake sediments gives us information on fire history, providing data on fire frequency, severity and what actually burned. And cores of lakes sediments gives us data that can be matched to tree burn scars but also can extend the record of fire for thousands of years into the past. Paleolimnology is an important tool for extending our historical records on climate and natural processes back thousands of years.
By looking at macroscopic charcoal deposited into small lakes during forest fires, we can determine fire frequency, fire intensity and the species that burned during the fire. In Part 1 of his presentation, Dr. Pisaric describes the sampling techniques (gravity core and Livingstone piston core), the types of lakes (small. level lakes) and the analytic techniques used in the Alberta montane forest fire paleolimnology studies (Hinton and Jasper National Park). Classifying microscopic carbon in the lake sediments can be sorted by morphology into different groups (grasses, needles, etc.). Dr. Pisaric introduces the question of dating sections of the lake sediment core at the end of Part 1.
In Part 2 of his presentation, Dr. Michael Pisaric describes how cores of lake sediments are dated. Geochronology is the main tool for dating lake core sediments (Carbon 14 dating of organic matter in the sediment, volcanic ash events, Cesium from atomic bomb testing). He then describes what has come from analysis of a small lake next to Jasper Park Lodge, Jasper National Park. The cores of lake sediments allow interpretation of fires frequency and severity back 2000 years. Combined with tree ring coring, the mean fire frequency is about 36 years; this agrees surprising well with tree ring data. Combined with data from other lakes, interpretations on climate and aspect can be made (e.g. Colin et al 2013, J. of Biogeography on the Late Holocene in SE British Columbia). Dr. Pisaric describes the analysis that came from the Kootenay analysis, aspect and climate effects. He concludes by describing the Jasper National Park study specifically and what are the effects of fire on lakes (and have they changed over time). He discusses in particular eutrophication and fires potential role in eutrophication.
Dr. Michael Pisaric is an Associate Professor at Brock University, St. Catharines, Ontario. His presentation was part of the July 10, 11 2013 Workshop and Tour on Burning Issues in Alberta's Forests: Fire Regimes in the Montane Forests of the Alberta Foothills and Jasper National Park. The workshop was sponsored by the Healthy Landscapes Program at the Foothills Research Instititute, Hinton, Alberta.
This presentation was recorded and originally hosted online by the Alberta Land Use Knowledge Network (LUKN).