Spatial Heterogeneity in the Shrub Tundra Ecotone in the Mackenzie Delta Region, Northwest Territories: Implications for Arctic Environmental Change

• Published in: Ecosystems (New York) Vol. 13; no. 2; pp. 194 - 204
• Main Authors: Lantz, Trevor C, Gergel, Sarah E, Kokelj, Steven V
• Format: Journal Article
• Language: English
• Published: New York New York : Springer-Verlag 01.03.2010; Springer Science+Business Media; Springer-Verlag; Springer; Springer Nature B.V
• Subjects: Air temperature; Albedo; Arctic environments; Biomedical and Life Sciences; Biophysics; Climate change; Ecology; Ecosystems; Ecotones; Energy balance; Environmental changes; Environmental Management; Evapotranspiration; Geoecology/Natural Processes; Heterogeneity; Hydrology/Water Resources; Image classification; Latent heat; Life Sciences; Marine ecosystems; Plant communities; Plant ecology; Plant Sciences; River deltas; Shrubs; Subshrubs; Tundra; Tundra ecology; Tundras; Vegetation; Vegetation structure; Zoology; PN, Arctic; PNW, Canada, Northwest Terr., Inuvik Region, Mackenzie Delta; object-based; object-oriented; Low Arctic; airphotos; vegetation classification; climate change
• ISSN: 1432-9840; 1435-0629
• DOI: 10.1007/s10021-009-9310-0

Growing evidence suggests that plant communities in the Low Arctic are responding to recent increases in air temperature. Changes to vegetation, particularly shifts in the abundance of upright shrubs, can influence surface energy balance (albedo), sensible and latent heat flux (evapotranspiration), snow conditions, and the ground thermal regime. Understanding fine-scale variability in vegetation across the shrub tundra ecotone is therefore essential as a monitoring baseline. In this article, we use object-based classifications of airphotos to examine changes in vegetation characteristics (cover and patch size) across a latitudinal gradient in the Mackenzie Delta uplands. This area is frequently mapped as homogenous vegetation, but it exhibits fine-scale variability in cover and patch size. Our results show that the total area and size of individual patches of shrub tundra decrease with increasing latitude. The gradual nature of this transition and its correlation with latitudinal variation in temperature suggests that the position of the shrub ecotone will be sensitive to continued warming. The impacts of vegetation structure on ecological processes make improved understanding of this heterogeneity critical to biophysical models of Low Arctic ecosystems.