Palynological Evidence for Postglacial Change in the Position of Tree Limit in Labrador

• Published in: Ecological Monographs
• Main Author: Lamb, H. F.
• Format: Article in Journal/Newspaper
• Language: English
• Published: Wiley 1985
• Subjects: Ecology, Evolution, Behavior and Systematics; Tundra
• Online Access: http://dx.doi.org/10.2307/1942559; http://api.wiley.com/onlinelibrary/tdm/v1/articles/10.2307%2F1942559; https://api.wiley.com/onlinelibrary/tdm/v1/articles/10.2307%2F1942559; https://onlinelibrary.wiley.com/doi/pdf/10.2307/1942559; https://esajournals.onlinelibrary.wiley.com/doi/pdf/10.2307/1942559

The postglacial history of the forest—tundra zone in Labrador is inferred from the pollen stratigraphy of sediment cores from four lakes which differ considerably in the size and relative relief of their hydrologic catchments. Local pollen—assemblage zones are established independently for each pollen sequence by numerical methods. The relative pollen stratigraphies, interpreted through multivariate statistical comparison with modern pollen spectra from the region, show an overall increase in the tundra component of the forest—tundra vegetation since °3000 BP. Decreasing absolute frequencies of Picea pollen in the sediments are interpreted as evidence of the decline in tree numbers within the lake catchments, and therefore as a potential record of lowering of the altitudinal tree limit. The records show diachronous changes between sites because of differences in catchment elevation and relief. Tree limit has apparently fallen at least 40 m between 3000 and 1000 BP. A further fall of 30 m may have taken place by 250 BP. High ground in northern Laborador makes it unlikely that any equivalent southward displacement of latitudinal tree line can be identified.