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TitleHolocene fire regimes and treeline migration rates in sub-arctic Canada
AuthorSulphur, K C; Goldsmith, S A; Galloway, J M; Macumber, A; Griffith, F; Swindles, G T; Patterson, R T; Falck, H; Clark, I D
SourceGlobal and Planetary Change 2016., (Open Access)
Alt SeriesEarth Sciences Sector, Contribution Series 20160260
PublisherElsevier BV
Mediapaper; on-line; digital
File formatpdf
ProvinceNorthwest Territories
NTS65C; 65D; 65E; 65F; 65K; 65L; 65M; 65N; 66C; 66D; 75; 76A; 76B; 76C; 76D; 85; 86A; 86B; 86C; 86D
Lat/Long WENS-120.0000 -100.0000 65.0000 60.0000
Subjectsenvironmental geology; paleontology; Nature and Environment; climate effects; paleoclimatology; arctic geology; fires; vegetation; vegetation history; palynological analysis; palynology; systematic palynology; ecosystems; paleoecology; climate, arctic; Holocene
Illustrationsphotographs; location maps; tables; graphs; cross-sections, stratigraphic
ProgramEnvironmental Geoscience, Metal Mining: northern baselines
AbstractHolocene climate change resulted in major vegetation reorganization in sub-arctic Canada near modern treeline. However, little is known of the effects of long-term climate change on boreal forest composition and fire regimes below treeline in this region. We present a high-resolution vegetation and fire history from two sites within the modern boreal forest in the central Northwest Territories, Canada, to provide new insight on sub-arctic vegetation response to Holocene climate dynamics and the role of fire in boreal ecosystems. Palynological analysis of sediments retrieved from Waite and Danny's lakes (informal) is used to reconstruct regional vegetation dynamics and boreal fire regimes. The longer Danny's Lake record documents treeline expansion beginning at ca. 7430-7220 cal yr BP. Integration of our new data with previous work shows that treeline expanded between ca. 4050 cal. yr BP and ca. 3840 cal yr BP at a rate of ca. 50 m/yr in response to the 1-2 °C increase in temperature estimated for the Holocene Thermal Maximum. Forest fires were relatively frequent during the early Holocene, before declining in frequency in response to development of cooler and wetter climate conditions associated with the Neoglacial (beginning after ca. 2200-2320 cal yr BP). We document a trend of increasing fire frequency in the 20th century that is not correlated with an increase in moisture at this time. These dynamics south of modern treeline provide insight into factors creating heterogeneity in plant community responses to large-scale climate events in high northern latitudes and suggest that large scale reorganization of boreal vegetation and fire regimes can be expected over the coming decades.
Summary(Plain Language Summary, not published)
A palynology study of two lakes (Danny's Lake and Waite Lake) and review of existing literature from sub-arctic Canada documents Holocene fire regimes and treeline change. The study shows that treeline expansion began ca. 7430-7220 cal yr BP following retreat of the Laurentide Ice Sheet in the Northwest Territories. During the Holocene Thermal Maximum (ca. 4050 cal yr BP) when temperatures increased by about 1-2 degrees C, treeline in the study region expanded at a rate of ca. 50 m/yr. Forest fires were relatively common during the early Holocene and decreased in frequency in response to wetter and cooler climate conditions associated with the Neoglacial (beginning after ca. 2200-2320 cal yr BP). This study documents a trend of increasing fire frequency in the 20th century.