Effects of timber harvest on carbon pools in Ozark forests

We quantified and compared carbon (C) pools at a Missouri Ozark experimental forest 8 years after different harvest treatments. Total C pools were 182, 170, and 130 Mg C * [ha.sup.-1] for the control (no-harvest management; NHM), singletree, uneven-age management (UAM), and clearcut even-age management (EAM) stands, respectively. Harvesting reduced the live tree C pool by 31% in the UAM, 93% in EAM stands, and increased the coarse woody debris (CWD) C pool by 50% in UAM and 176% for EAM, compared with NHM stands. UAM significantly (p = 0.02) increased the mineral soil C pool by 14%, whereas EAM had no effect. More interestingly, the distribution of C among various components (i.e., live, dead wood, CWD, litter, and soil) ranged from 0.7% to 29% on NHM stands and from 0.1% to 43% on EAM stands. Soil nitrogen (N) (%) was significantly correlated with soil C (%) in the UAM stands, whereas soil temperature was negatively related to live tree C. Soil N (%) and canopy cover were significantly correlated with live tree and soil C (%) pools at EAM stands. Our results revealed that the largest C pool in these forests was living trees. The soil and CWD C pool sizes suggest the importance of dynamics of decaying harvest debris, which influences N retention. Nous avons quantifie et compart; les reservoirs de carbone (C) dans une foret experimentale situtie dans les monts Ozark au Missouri huit ans apres que differents traitements de recolte eurent ete appliques. La quantite totale de carbone dans les differents reservoirs de carbone atteignait respectivement 182, 170 et 130 Mg C * [ha.sup.-1] dans le traitement temoin (amenagement sans recolte), avec un amenagement inequienne par pied d'arbre (AIPA) et avec un amenagement equienne et une coupe a blanc (AECB). La recolte a reduit le reservoir de C des arbres vivants de 31% dans le systeme AIPA et de 93% dans le systeme AECB et augmente le reservoir de C dans les debris ligneux grossiers (DLG) de 31% dans le systeme AIPA et de 176% dans le systeme AECB comparativement aux peuplements non recoltes. Le systeme AIPA a significativement (p = 0,02) augmente le reservoir de C du sol mineral de 14% tandis que le systeme AECB n'a eu aucun effet. Il etait plus interessant de constater que la distribution de C parmi les diverses composantes (c.-a-d. le bois vivant, le bois mort, les DLG, la litiere et le sol) variait de 0,7% a 29% dans les peuplements non coupes et de 0,1% a 43% dans les peuplements coupes a blanc. L'azote (N) (%) dans le sol etait significativement correle avec le C (%) dans le sol dans le systeme AIPA. Nos resultats revelent que le plus important reservoir de C dans ces forets est constitue des arbres vivants. La dimension des reservoirs de C du sol et des DLG montre l'importance de la dynamique de la decomposition des dechets de coupe qui influence la retention de N. [Traduit par la Redaction]
Introduction Carbon (C) pools in terrestrial ecosystems are receiving increasing attention partly because terrestrial ecosystems have some potential to store C and, thus, help offset increases in atmospheric carbon dioxide [...]