Climate, soil organic layer, and nitrogen jointly drive forest development after fire in the North American boreal zone

Trugman, A. T., Fenton, N. J., Bergeron, Y., Xu, X., Welp, L. R. et Medvigy, D. (2016). Climate, soil organic layer, and nitrogen jointly drive forest development after fire in the North American boreal zone. Journal of Advances in Modeling Earth Systems , 8 (3). pp. 1180-1209. doi:10.1002/2015MS000576 Repéré dans Depositum à https://depositum.uqat.ca/id/eprint/928

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Résumé

Previous empirical work has shown that feedbacks between fire severity, soil organic layer thickness, tree recruitment, and forest growth are important factors controlling carbon accumulation after fire disturbance. However, current boreal forest models inadequately simulate this feedback. We address this deficiency by updating the ED2 model to include a dynamic feedback between soil organic layer thickness, tree recruitment, and forest growth. The model is validated against observations spanning monthly to centennial time scales and ranging from Alaska to Quebec. We then quantify differences in forest development after fire disturbance resulting from changes in soil organic layer accumulation, temperature, nitrogen availability, and atmospheric CO2. First, we find that ED2 accurately reproduces observations when a dynamic soil organic layer is included. Second, simulations indicate that the presence of a thick soil organic layer after a mild fire disturbance decreases decomposition and productivity. The combination of the biological and physical effects increases or decreases total ecosystem carbon depending on local conditions. Third, with a 48C temperature increase, some forests transition from undergoing succession to needleleaf forests to recruiting multiple cohorts of broadleaf trees, decreasing total ecosystem carbon by �40% after 300 years. However, the presence of a thick soil organic layer due to a persistently mild fire regime can prevent this transition and mediate carbon losses even under warmer temperatures. Fourth, nitrogen availability regulates successional dynamics; broadleaf species are less competitive with needleleaf trees under low nitrogen regimes. Fifth, the boreal forest shows additional short-term capacity for carbon sequestration as atmospheric CO2 increases.

Type de document:	Article
Informations complémentaires:	Licence d'utilisation : CC-BY-NC-ND
Mots-clés libres:	boreal forest; carbon cycle; climate sensitivity; dynamic vegetation model; fire disturbance; soil organic layer
Divisions:	Forêts
Date de dépôt:	19 mars 2020 13:01
Dernière modification:	26 mars 2020 14:56
URI:	https://depositum.uqat.ca/id/eprint/928

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