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Observations of the rapid growth and slow decomposition of American chestnut (Castanea dentata (Marsh.) Borkh.) suggest that its reintroduction could enhance terrestrial carbon (C) sequestration. A suite of decomposition models was fit with decomposition data from coarse woody debris (CWD) sampled in Wisconsin and Virginia, U.S. The optimal (two-component exponential) model was integrated with generic growth curves and documented longevity and typical stem density to evaluate how CWD and biomass pools relate to decomposition. CWD decomposed faster in Wisconsin (4.3% ± 0.3% per year) than in Virginia (0.7% ± 0.01% per year), and downed dead wood decomposed faster (8.1% ± 1.9% per year) than standing dead wood (0.7% ± 0.0% per year). We predicted considerably smaller CWD pools in Wisconsin (maximum 41 ± 23 Mg C·ha -1 ) than in Virginia (maximum 98 ± 23 Mg C·ha -1 ); the predicted biomass pool was larger in the faster growing Wisconsin trees (maximum 542 ± 58 Mg C·ha -1 ) compared with slower growing trees in Virginia (maximum 385 ± 51 Mg C·ha -1 ). Sensitivity analysis indicated that accurate estimates of decomposition rates are more urgent in fertile locations where growth and decomposition are rapid. We conclude that the American chestnut wood is intermediate in resistance to decomposition. Due to the interrelatedness of growth and decomposition rates, CWD pool sizes likely do not depend on species alone but on how the growth and decomposition of individual species vary in response to site productivity.Résumé : Les observations ayant trait à la croissance rapide et à la décomposition lente du châtaignier d'Amérique (Castanea dentata (Marsh.) Borkh.) indiquent que sa réintroduction pourrait accroître la séquestration terrestre du carbone. Une série de modèles de décomposition ont été ajustés aux données de décomposition de débris ligneux grossiers (DLG) échantillonnés au Wisconsin et en Virginie, aux États-Unis. Le modèle optimal (exponentiel à deux composantes), des courbes génériques de croissance, la longévité documentée et la densité typique de la tige ont été intégrés pour évaluer comment les DLG et les réservoirs de biomasse sont reliés à la décomposition. Les DLG se décomposaient plus rapidement au Wisconsin (4,3 ± 0,3 %·an -1 ) qu'en Virginie (0,7 ± 0,01 %·an -1 ) et les débris au sol se décomposaient plus rapidement (8,1 ± 1,9 %·an -1 ) que les débris sur pied (0,7 ± 0,0 %·an -1 ). Nous avons prédit que les réservoirs de DLG seraient considérablement plus petits au Wisconsin (maximum de 41 ± 23 Mg C·ha -1 ) qu'en Virginie (maximum de 98 ± 23 Mg C·ha -1 ); nous avons aussi prédit que le réservoir de biomasse serait plus gros chez les arbres du Wisconsin qui croissent plus vite (maximum de 542 ± 58 Mg C·ha -1 ) comparativement à ceux de la Virginie (maximum de 385 ± 51 Mg C·ha -1 ). Une analyse de sensibilité a indiqué qu'il était plus urgent d'obtenir des estimations précises du taux de décomposition dans les endroits fertiles où la croissance et la décomposition sont rapides. Nous arrivons à la conclusion...

Abstract. In the eastern United States, American chestnut (Castanea dentata) was historically a major component of forest communities, but was functionally extirpated in the early 20th century by an introduced pathogen, chestnut blight (Cryphonectria parasitica). Because chestnut is fast-growing, long-lived, and resistant to decay, restoration of American chestnut using blight-resistant stock could have the potential to increase carbon sequestration or storage in forested landscapes. However, carbon dynamics are also affected by interspecific competition, succession, natural disturbance, and forest management activities, and it is unknown how chestnut restoration might interact with these other processes. We used the PnETSuccession extension of the LANDIS-II forest landscape model to study the implications of chestnut restoration on forest composition and carbon storage in the context of other disturbances, including timber harvest and insect pest outbreaks. Our results imply that it could take a millennium or more for chestnut to fully occupy landscapes without aggressive restoration efforts. When successful, chestnut restoration activities displaced other species approximately in proportion to their abundance on the landscape, rather than replacing a single species or genus (e.g., Quercus). Insect pests increased the rate of chestnut colonization by reducing the abundance of competitors, and also had a dominant effect on carbon dynamics. Although chestnut is fast-growing, moderately shade-tolerant, and decomposes very slowly, our results suggest that it can only modestly increase the carbon storage potential of eastern forests. However, our results also demonstrate that compositional changes in forest communities can have noticeable effects on biomass accumulation, even with the large uncertainties introduced by invasive pests.