The changing effects of Alaska's boreal forests on the climate system

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Date: July 2010
From: Canadian Journal of Forest Research(Vol. 40, Issue 7)
Publisher: NRC Research Press
Document Type: Report
Length: 8,181 words

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Abstract :

In the boreal forests of Alaska, recent changes in climate have influenced the exchange of trace gases, water, and energy between these forests and the atmosphere. These changes in the structure and function of boreal forests can then feed back to impact regional and global climates. In this manuscript, we examine the type and magnitude of the climate feedbacks from boreal forests in Alaska. Research generally suggests that the net effect of a warming climate is a positive regional feedback to warming. Currently, the primary positive climate feedbacks are likely related to decreases in surface albedo due to decreases in snow cover. Fewer negative feedbacks have been identified, and they may not be large enough to counterbalance the large positive feedbacks. These positive feedbacks are most pronounced at the regional scale and reduce the resilience of the boreal vegetation--climate system by amplifying the rate of regional warming. Given the recent warming in this region, the large variety of associated mechanisms that can alter terrestrial ecosystems and influence the climate system, and a reduction in the boreal forest resilience, there is a strong need to continue to quantify and evaluate the feedback pathways. Resume: Dans la forets boreale de l'Alaska, les recents changements climatiques ont influence les echanges de gaz a l'etat de trace, d'eau et d'energie entre ces forets et l'atmosphere. Ces changements dans la structure et la fonction des forets boreales peuvent en retour avoir un impact sur le climat regional et mondial. Dans cet article, nous examinons le type et l'ampleur des retroactions climatiques des forets boreales de l'Alaska. De facon generale, les travaux de recherche indiquent que l'effet net d'un rechauffement climatique est une retroaction regionale positive au rechauffement. Actuellement, les principales retroactions climatiques positives sont probablement reliees a la diminution de l'albedo en surface due a la reduction du couvert nival. Moins de retroactions negatives ont ete identifiees et elles ne sont peut-etre pas assez importantes pour contrebalancer les importantes retroactions positives. Ces retroactions positives sont les plus fortes a l'echelle regionale et reduisent la resilience du systeme vegetation--climat boreal en amplifiant le taux de rechauffement regional. Etant donne le recent rechauffement dans cette region, la grande variete de mecanismes associees qui peuvent modifier les ecosystemes terrestres et influencer le systeme climatique, et une reduction de la resilience de la foret boreale, il est imperatif de continuer a quantifier et a evaluer les modes de retroaction. [Traduit par la Redaction]

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Gale Document Number: GALE|A234251129