Response to canopy opening does not act as a filter to Fagus sylvatica and Acer sp. advance regeneration in a mixed temperate forest

Abstract

Abstract• In mixed-species forest stands, large losses in tree species diversity often occur during the regeneration phase. In a former coppice-with-standards, we investigated whether the limiting stage in the recruitment process of advance regeneration is the immediate seedling response to canopy release. Experimental canopy gaps were opened and the survival and growth of advance seedlings (Fagus sylvatica, Acer pseudoplatanus, Acer campestre, Acer platanoides) growing in the gaps or under closed canopy were monitored for three years.• All species responded positively and rapidly to canopy release. Survival was not affected by gap opening. Diameter increment after gap opening was similar across species, and height increment was greater for Acer platanoides and for Acer pseudoplatanus. Post-release diameter and height growth were mainly determined by pre-release seedling size. Competition from neighbouring seedlings did not affect growth in the three years following canopy opening.• In the recruitment process of F. sylvatica and Acer sp. advance regeneration, the recovery from canopy release did not appear as a limiting step that would filter against some species. Pre-release size was the main factor accounting for post-release growth and is probably a major determinant of long-term seedling dominance. Mots-clés :trouée forestière / acclimatation à la lumière / tolérance à l'ombre / Acer pseudoplatanus / Acer campestre / Acer platanoides Résumé -La réponse à l'ouverture du couvert ne filtre pas les semis préexistants de Fagus sylvatica et Acer sp. dans une forêt mélangée tempérée.• Dans les peuplements mélangés, une forte réduction de la diversité spécifique a lieu au cours de la phase de régénération. Nous avons examiné dans un ancien taillis-sous-futaie dans quelle mesure la réponse immédiate des semis à l'ouverture du couvert adulte pouvait limiter le recrutement de semis préexistants. Des trouées ont été ouvertes dans le couvert, et la survie et la croissance de semis pré-existants (Fagus sylvatica, Acer pseudoplatanus, Acer campestre, Acer platanoides), situés dans les trouées ou bien sous couvert fermé, ont été suivies pendant trois années.• Les quatre espèces ont répondu positivement et rapidement à l'ouverture du couvert. La survie n'a pas été affectée par l'ouverture. Pour les semis dans les trouées, l'accroissement en diamètre était similaire pour les quatre espèces et l'accroissement en hauteur était plus important pour Acer platanoides et Acer pseudoplatanus. La croissance en hauteur et en diamètre après ouverture étaient principalement déterminées par les dimensions des semis avant ouverture. La compétition exercée par les semis voisins n'a pas affecté significativement la croissance dans les trois années qui ont suivi l'ouverture.• La période d'acclimatation des semis aux nouvelles conditions après ouverture de la canopée n'est pas apparue comme un stade limitant le recrutement des semis préexistants de Fagus sylvatica, Acer sp., ni comme un filtre vis-à-vis de l'une des quatre espèces. Les dimensi...

Effects of shrub and canopy cover on the relative growth rate of Pinus pinaster Ait. seedlings of different sizes

“…The relative growth rate varied significantly in relation to seedling size and was higher for larger seedlings irrespective of shrub environment. This suggests that seedling social status and size prior to shrub removal may be important factors in post-removal growth (Casquet et al 2010). Shrub removal treatment had no significant effect per se on the relative growth rate except in the case of size 2 seedlings under open canopy, which showed the highest competitive-response ability.…”

Ungulate browsing causes species loss in deciduous forests independent of community dynamics and silvicultural management in Central and Southeastern Europe

“…In our study, the structural equation analysis detected a more consistent effect of browsing than of light, confi rming Abs et al (2008) who showed that the light requirements of Fagus are very similar to those of Tilia and Ulmus, and that shade tolerance of Acer pseudoplatanus and Acer platanoides even exceeds the shade tolerance of Fagus. If protected from browsing, non-Fagus species would become dominant even under conditions of shade (Striepen 2000, Caquet et al 2009). In our study, Fagus had already become dominant by the third height class, having totally suppressed Acer platanoides.…”

Marginal fragmented beech stands and climate change in Sicily: effects of non-sustainable traditional silviculture practices in relation to micro-topographic gradient

“…L'effetto negativo degli intensi interventi di taglio del ceduo effettuati nelle aree indagate (aree campione A, C, D) ha aumentato lo stress ambientale ed ecologico (in termini di modelli di crescita, processi di rinnovazione, effetti dei raggi solari -per esempio si veda: Caquet et al, 2009;Collet et al, 2001;Topoliantz e Ponge, 2000;Robson et al, 2009) dovuto alla frammentazione della copertura forestale e all'apertura delle chiome.…”