Ecosystem carbon stocks in Pinus palustris forests

Longleaf pine (Pinus palustris Mill.) restoration in the south eastern United States offers opportunities for carbon (C) sequestration. Ecosystem C stocks are not well understood in longleaf pine forests, which are typically of low density and maintained by prescribed fire. The objectives of this research were to develop allometric equations for above- and below-ground biomass and quantify ecosystem C stocks in five longleaf pine forests ranging in age from 5 to 87 years and in basal area from 0.4 to 22.6 [m.sup.2] x [ha.sup.-1]. Live aboveground C (woody plant + ground cover) and live root C (longleaf pine below stump + plot level coarse roots + plot level fine roots) ranged from 1.4 and 2.9 Mg C x [ha.sup.-1], respectively, in the 5-year-old stand to 78.4 and 19.2 Mg C x [ha.sup.-1], respectively, in the 87-year-old stand. Total ecosystem C (live plant + dead organic matter + mineral soil) values were 71.6, 110.1, 124.6,141.4, and 185.4 Mg C x [ha.sup.-1] in the 5-, 12-, 21-, 64-, and 87-year-old stands, respectively, and dominated by tree C and soil C. In the 5- year-old stand, ground cover C and residual taproot C were significant C stocks. This unique, in-depth assessment of above and below-ground C across a series of longleaf pine stands will improve estimates of C in longleaf pine ecosystems and contribute to development of general biomass models that account for variation in climate, site, and management history in an important but understudied ecosystem. Key words: longleaf pine, carbon sequestration, allometry, roots, ground- penetrating radar. La restauration du pin des marais (Pinus palustris Mill.) dans le sud-est des Etats-Unis off re une opportunity de stocker du carbone (C). Les stocks de C de l'ecosysteme ne sont pas bien connus dans les forets de pin des marais qui ont typiquementune faible densite et se maintiennent grace au brulage dirigee. Les objectifs de ces travaux de recherche consistaient a elaborer des equations allometriques pour la biomasse aerienne et souterraine et a quantifier les stocks de C de l'ecosysteme dans cinq forets de pin des marais dont l'age allait de 5 a 87 ans et dont la surface terriere variait de 0,4 a 22,6 [m.sup.2] x [ha.sup.-1]. Le C aerien vert (plantes ligneuses + couverture vegetale) et le C des racines vivantes (souches de pin des marais + grosses racines et racines fines presentes dans les placettes) variaient respectivement de 1,4 et 2,9 Mg C x [ha.sup.-1]dans le peuplement age de 5 ans a 78,4 et 19,2 Mg C x [ha.sup.-1] dans le peuplement age de 87 ans. Le C total de l'ecosysteme (plantes vivantes + matiere organique morte + sol mineral) atteignait respectivement 71,6,110,1,124,6,141,4 et 185,4 Mg C x [ha.sup.-1] dans les peuplements ages de 5,12, 21, 64 et 87 ans et etait domine par le C des arbres et du sol. Dans le peuplement age de 5 ans, le C contenu dans la couverture vegetale et les racines pivotantes residuelles constituait un stock important de C. Cette evaluation unique et approfondie du C aerien et souterrain dans une serie de peuplements de pin des marais ameliorera les estimations du C dans les ecosystemes domines par cette essence et contribuera au developpement de modeles generaux de biomasse qui tiennent compte de la variation dans le climat, la station et l'historique d'amenagement dans un ecosysteme important mais peu etudie. [Traduit par la Redaction] Mots-cles: pin des marais, sequestration du carbone, allometrie, racines, georadar.
Introduction Forests serve as a means for mitigating climate change by acting as sinks for atmospheric C[O.sub.2] and storing carbon (C) in plant biomass, detritus, and forest soils. In the [...]