Extensive land cover change across Arctic-Boreal Northwestern North America from disturbance and climate forcing

TitleExtensive land cover change across Arctic-Boreal Northwestern North America from disturbance and climate forcing
Publication TypeJournal Article
Year of Publication2019
AuthorsWang J.A, Sulla-Menashe D., Woodcock C.E, Sonnentag O., Keeling RF, Friedl M.A
Date Published2019/10
Type of ArticleArticle; Early Access
ISBN Number1354-1013
Accession NumberWOS:000486743500001
KeywordsArctic; atmospheric co2; Biodiversity & Conservation; Boreal forest; classification; deciduous forest; encroachment; Environmental Sciences & Ecology; estimating area; evergreen; Fire; forest; forest disturbance; land cover change; map accuracy; patterns; plant functional type; productivity; Remote sensing; shrub; variability; wildfire

A multitude of disturbance agents, such as wildfires, land use, and climate-driven expansion of woody shrubs, is transforming the distribution of plant functional types across Arctic-Boreal ecosystems, which has significant implications for interactions and feedbacks between terrestrial ecosystems and climate in the northern high-latitude. However, because the spatial resolution of existing land cover datasets is too coarse, large-scale land cover changes in the Arctic-Boreal region (ABR) have been poorly characterized. Here, we use 31 years (1984-2014) of moderate spatial resolution (30 m) satellite imagery over a region spanning 4.7 x 10(6) km(2) in Alaska and northwestern Canada to characterize regional-scale ABR land cover changes. We find that 13.6 +/- 1.3% of the domain has changed, primarily via two major modes of transformation: (a) simultaneous disturbance-driven decreases in Evergreen Forest area (-14.7 +/- 3.0% relative to 1984) and increases in Deciduous Forest area (+14.8 +/- 5.2%) in the Boreal biome; and (b) climate-driven expansion of Herbaceous and Shrub vegetation (+7.4 +/- 2.0%) in the Arctic biome. By using time series of 30 m imagery, we characterize dynamics in forest and shrub cover occurring at relatively short spatial scales (hundreds of meters) due to fires, harvest, and climate-induced growth that are not observable in coarse spatial resolution (e.g., 500 m or greater pixel size) imagery. Wildfires caused most of Evergreen Forest Loss and Evergreen Forest Gain and substantial areas of Deciduous Forest Gain. Extensive shifts in the distribution of plant functional types at multiple spatial scales are consistent with observations of increased atmospheric CO2 seasonality and ecosystem productivity at northern high-latitudes and signal continental-scale shifts in the structure and function of northern high-latitude ecosystems in response to climate change.

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