Biomass increment and carbon balance of ash (Fraxinus excelsior) trees in an experimental stand in northeastern France

Abstract

-In this study, we compared the annual biomass increment of ash trees to their annual carbon balance calculated from the end of the growing season in 1994 to the end of the next one in 1995. In 1995, three trees of variable competitive status and aged 25 were studied. Stem, branch and root biomass increments were derived from detailed measurements. Tree crowns were divided vertically into three layers. In each crown layer, the foliage biomass and area were determined, net CO 2 assimilation (A n ) and global radiation (R g ) were measured regularly throughout the growing season. Outside this period, R g was estimated from global radiation measured above the canopy and from estimations of light transmittance. Net assimilation of trees (A N ) was obtained by scaling leaf A n to the tree level, using relations established between A n and R g for each crown layer, the distribution of foliage area, and measured climatic data. Above-and below-ground tree respirations, not measured, were estimated. A n was correlated to R g and potential evapotranspiration. It decreased from the upper to the lower crown layers, but was independent of tree competitive status. Total estimated respiration of trees accounted for about 37% of gross assimilation. The proportion of carbon allocated to the stem was more than 45%. Net productivity of trees obtained from simulated annual carbon fluxes compared reasonably well with the biomass increment of trees.biomass partitioning / carbon assimilation / respiration / scaling / leaf area Résumé -Accroissement en biomasse et bilan de carbone du frêne dans un peuplement expérimental du nord-est de la France. Cette étude avait pour but de comparer l'accroissement annuel en biomasse de frênes à leur bilan de carbone établi par estimation de la photosynthèse et de la respiration sur une année complète (depuis la fin de la saison de végétation 1994 à la fin de celle de 1995). En 1995, trois frênes de différents statuts concurrentiels âgés de 25 ans ont été étudiés. Les accroissements en biomasse de la tige, des branches et des racines ont été obtenus à partir de mesures détaillées. Les houppiers des arbres ont été divisés verticalement en trois strates. Pour chaque strate, les variables suivantes ont été mesurées: la biomasse et la surface foliaires, la photosynthèse et le rayonnement global (R g ) pendant la période de croissance. En dehors de cette période, le rayonnement global a été estimé à partir du rayonnement global hors couvert et de valeurs estimées de la transmittance pour chaque strate. L'assimilation nette des arbres (A N ) a été obtenue en extrapolant l'assimilation nette foliaire (A n ) à partir des relations établies entre A n et R g pour chaque strate du houppier, de la distribution du feuillage par strate et des données climatiques mesurées. La respiration des arbres, non mesurée, a été estimée. L'assimilation nette A n est liée à R g et à l'évapotranspiration potentielle et décroît du haut vers le bas du houppier ; elle est indépendante du statut concurrentiel des arbres. L...

Aboveground biomass relationships for mixed ash (Fraxinus excelsior L. and Ulmus glabra Hudson) stands in Eastern Prealps of Friuli Venezia Giulia (Italy)

“…Wood density values found are similar to those reported by Nardi Berti [12] and by Le Goff et al [11]. Ash wood density trend (Fig.…”

Conversion of a natural broad-leafed evergreen forest into pure plantation forests in a subtropical area: Effects on carbon storage

“…However, the effects of conversion of natural forest to tree plantation have less been assessed. Carbon stocks of both natural and plantation forests are well documented [5,9,11,19,21,23,29,43,47], in terms of carbon sequestration, however, the relative importance of each is often confused.…”

Forest and shrubland canopy carbon uptake in relation to foliage nitrogen concentration and leaf area index: a modelling analysis

“…While the use of multi-layer models for scaling CO 2 exchange from leaves to canopies has been well tested in forests [8,28,63], there has generally been much more emphasis on measurements for obtaining parameter values of photosynthesis than those needed for respiration [29]. Our results highlight the need for careful determination of parameter values for respiration in models.…”