limite septentrionale des arbres

CONT: Depuis 3 500 ans BP, la limite septentrionale des arbres est demeurée stable dans tout l'hémisphère nord.
OBS: Plus de 80 % de la superficie du Canada située au sud de la limite septentrionale des arbres est boisée.

CONT: The northern treeline represents an abrupt change in surface characteristics and microclimate, from the high leaf area index, tall, deeply rooting boreal forest to the low leaf area index, shallow rooting and short stature of tundra grasses and shrubs.
CONT: The northern treeline is generally controlled by a temperature deficit, often modified by local conditions (such as permafrost occurrence). Recent studies however, identified a shift from temperature to moisture control in many places (such as Alaska), non-linear relationships between climate and tree growth, sub-population behaviour at northern treeline and the ""divergence effect"" (an underestimation of recent warming trends by tree ring based proxies).