Hoffman, Kira M.;
Lertzman, Ken P.;
Starzomski, Brian M.
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2018-09-15
Aim
Few long-term fire histories have been reconstructed in coastal temperate rain forests, and little is known regarding the spatial and temporal characteristics of lightning and human ignitions. We use a multidisciplinary approach to assess the impact, scale and ecological legacies of historic fires.
Location
We focus on perhumid temperate rain forests located on the central coast of British Columbia, Canada.
Methods
We reconstructed 700 years of temporal and spatial aspects of fire activity with 30 plots on Hecate Island using fire scars and forest-stand establishment. We then conducted a paired study of 20 former indigenous habitation and control sites on 15 islands to relate fire activity to patterns of human settlement. We mapped 15 years of lightning strike densities and use mixed-effects modelling to assess whether fire activity predicted the distribution and abundance of traditional plants.
Results
Sixteen low- and mixed-severity fires were recorded from 1376 to 1893. The abundance of traditional plants and the density of western redcedar trees were best predicted by the location of former habitation sites and shorter mean fire intervals. Lightning is too rare to explain the pattern of fire activity in the study area. No fire activity was detected after 1893, coinciding with the relocation of indigenous groups from the study area.
Main conclusions
Fire was strongly associated with former indigenous habitation sites during the periods of occupation. People likely utilized fire as a tool for resource management to influence the densities of specific plants by creating mosaics of vegetation in different stages of succession. By assessing the ecological impacts of historic fire events, we gain a better understanding of the abrupt changes that occurred in the 20th century. Our ability to understand present-day temperate rain forest ecosystems may be compromised if we underestimate the role of humans in driving historic fire activity.
