Root biomass and biomass increment in a beech (Fagus sylvatica L.) stand in North-East France

Abstract

-This study is part of a larger project aimed at quantifying the biomass and biomass increment of an experimental beech stand aged 30 years, and comparing the carbon sequestration in trees to carbon fluxes. The below ground part of trees is expected to play an important role in carbon sequestration. A method has been developed to estimate the biomass and biomass increment of coarse, small and fine roots of trees from root system excavations of sampled trees of different crown classes. The biomass and biomass increment of broken root ends during excavation was estimated from the diameter of the roots at the broken points. Equations were then established relating the biomass and biomass increment of the different root categories to tree DBH. These equations were then used to estimate the root biomass and biomass increment of the experimental stand from stem inventory, for the different root categories. Trees from dominant and codominant crown classes contribute for more than 80% to below ground biomass and biomass increment of the stand. root system / biomass / biomass increment / biomass distribution / Fagus sylvatica Résumé -Biomasse et accroissement en biomasse du système racinaire dans un peuplement de hêtre du Nord-Est de la France. Cette étude fait partie d'un projet plus vaste ayant pour objectif l'estimation de la biomasse aérienne et souterraine d'un peuplement expérimental de hêtre de 30 ans et de son accroissement, pour comparer la quantité de carbone séquestrée annuellement dans les arbres aux flux de carbone mesurés par les échanges gazeux. La partie souterraine des arbres paraît jouer un rôle important dans la séquestration du carbone. Une méthode a été développée pour estimer la biomasse et l'accroissement en biomasse des racines de différentes catégories de grosseur grâce à l'extraction du sol de systèmes racinaires d'un échantillon d'arbres représentatif des diffé-rentes classes de statut social du peuplement. La biomasse et l'accroissement en biomasse des parties de racines cassées lors de l'extraction du sol ont pu être estimés, pour chaque catégorie de racine, à partir du diamètre des racines au niveau de la cassure. Des relations ont ensuite été établies entre la biomasse racinaire et son accroissement, pour chaque catégorie de racines, et le diamètre de l'arbre à 1,30 m. Ces équations ont été utilisées pour estimer les biomasses au niveau du peuplement à partir de l'inventaire des arbres. Les arbres dominants et codominants du peuplement contribuent pour plus de 80 % à la biomasse souterraine du peuplement et à son accroissement. système racinaire / biomasse / accroissement de la biomasse / répartition de la biomasse / Fagus sylvatica

Distribution of roots and arbuscular mycorrhizal associations in tropical forest types of Xishuangbanna, southwest China

“…So as different plant species develop different adaptations for their survival in a given environment, meaningful comparisons between root characteristics and their distribution in tropical forests under varied environmental conditions are difficult. Further, root biomass production depends on the species composition and ecological conditions (Goff and Ottorini, 2001). However, the root estimates recorded in the secondary forest are comparable to the few estimates for other tropical secondary forests (Berish, 1982;Hopkins et al, 1996;Raich, 1983), but comparisons of secondary forests are also difficult due to the confounding influence of forest age and structure.…”

Beech (Fagus sylvatica L.) branches show acclimation of xylem anatomy and hydraulic properties to increased light after thinning

“…There were three types of branches: (i) upper branches exposed to full sunlight (= sun-exposed branches), (ii) lower branches were heavily shaded in 1998 by upper crown branches and surrounding trees (= shade branches) and (iii) branches exposed directly to full sun after thinning in 1999 (= thinned branches). More details about the stand structure are published elsewhere [7,12,[14][15][16] and microclimate is characterised in table I for each treatment. Branch morphology, xylem anatomy and water relations were measured on the five trees accessible from towers.…”

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

“…In a similar way as described by Le Goff and Ottorini [27], the biomass of missing root ends of each tree was estimated to obtain annual biomass increments of the root systems. This was done, in addition, accounting, where possible, for the morphological type of roots (tape, horizontal).…”