The effects of thinning on the structural diversity of coppice forests

Abstract

-Coppices are currently at a turning point: traditional uses have been abandoned and silviculture must be redefined according to new uses. Thinning to improve the development of trees is often the silvicultural treatment chosen. This paper attempts to assess the changes in forest structural diversity induced by different thinning regimes applied in coppice stands of Quercus pyrenaica and Quercus faginea. Structural diversity is analysed through spatial pattern, crown dimensions, vertical and horizontal differentiation and foliage height diversity. Moderate and heavy thinning have similar effects on stand structure, but the effects of light thinning are quite different for both species. The spatial pattern shows a greater regularity as the intensity of the thinning regime increases. The response of Q. pyrenaica to thinning is noticeable both in tree height and crown diameter, whilst in the case of Q. faginea, trees reacted to thinning by developing epicormic sprouts on the stem from the base of the crown. Vertical differentiation shows opposite trends in both species: increasing the intensity of thinning leads to an increase in vertical differentiation with Q. pyrenaica, but to a greater homogenisation shortly after thinning with Q. faginea. A neighbourhood analysis using Gadow's differentiation index is able to provide useful information on the changes in microstructure, while foliage height diversity index can be used to describe complex changes in the vertical structure of the stand. coppice / Quercus pyrenaica / Quercus faginea / structural diversity / thinning Résumé -L'effet des éclaircies sur la diversité structurale des taillis. Aujourd'hui, les taillis se trouvent à une phase de changement : on a renoncé à leur usage traditionnel, et alors la sylviculture est obligée de les redéfinir selon les nouveaux usage qu'on propose. Le recours aux éclaircies pour améliorer le croissance des arbres est le traitement de préférence. Ce travail a pour but l'identification des changements qui se sont produits dans la diversité structurale du peuplement, et qui ont été induits par l'application des divers types d'éclaircies sur les taillis de Quercus pyrenaica y Quercus faginea. La diversité structurale est étudiée avec l'analyse du modèle de répartition des tiges, de la taille des cimes, de la différenciation tant horizontale que verticale et des variations de hauteur du feuillage. Les éclaircies moyennes et fortes ont à peu près le même effet sur la structure du peuplement, mais l'effet des éclaircies plus légères est bien différent dans les deux espèces. Le modèle spatial montre une plus grande régularité au fur et à mesure que l'intensité de l'éclaircie augmente. La réponse de Quercus pyrenaica à l'éclaircie est bien évidente tant en ce qui concerne la croissance en hauteur que le diamètre de la cime. Mais pour Quercus faginea, les arbres vont réagir d'une autre façon, avec l'émission de bourgeons adventifs dès la partie inférieure de la couronne. La différenciation verticale va montrer deux tendances diffé...

Response of diameter and height increment to thinning in oak-hornbeam coppice in the southeastern part of the Czech Republic

“…Now the previously practised method shifted to thinning to improve the development of trees in coppices (Montes et al 2004). The reasons for thinning are economic, ecophysiological, and ecological.…”

Xylem and soil CO2 fluxes in a Quercus pyrenaica Willd. coppice: root respiration increases with clonal size

“…4 (c, e)) main problems result from a lack of knowledge about what constitutes a functional unit in these ecosystems, and the technical difficulties of surveying the belowground attributes of individuals. Thinning has been advised for conversion of abandoned oak coppices into high forest, as it can enhance growth of residual trees, improve stand structure, and reduce excessive stand density (Montes et al 2004;Bravo et al 2008;Rodríguez-Calcerrada et al 2011). However, thinning multistemmed trees could also intensify structural and physiological imbalances between shoots and roots.…”

“…The carbon imbalance suggested by our results has silvicultural implications. Management of oak coppices is one of the largest problems currently facing Mediterranean silviculture Montes et al 2004). The increasing interest in implementing new uses for these abandoned stands justifies the urgent need to study them.…”

Structural diversity of selected oak stands (Quercus robur L.) on the Krotoszyn Plateau in Poland

“…stand structure is affected by both external factors (natural disturbances, such as fires and insect infestations) and internal ones (ecological processes, biological and ecological species characteristics, microhabitat variability, etc.) (Müller et al 2000;Montes et al 2004;Zenner 2004;Pretzsch 2010;Petritan et al 2012;Petritan et al 2015;Zenner et al 2014;del rio et al 2015;Fibich et al 2016). In managed forests, an additional factor significantly influencing the stand structure in various stages of development is silvicultural practices (Pretzsch, 2010).…”