Initial spacing has little influence on transient epicormic shoots in a 20-year-old sessile oak plantation

Abstract

-• Epicormics are important defects of oak timber which originate from suppressed buds placed early and develop into epicormic shoots depending on the light available, which in turn depends on stand density. In this context, our objective was to assess the epicormic shoots present in a 20-year-old experimental plantation of sessile oak and to test and quantify the effect of the three initial densities applied: 1333, 2667 and 5333 stems/ha.• In the 3 stand densities, epicormic shoots were mostly transient and were rarely clustered. A significant but negligible effect of the density on the epicormic length and on the variables related to epicormic counts appeared: the longest epicormic shoots were present in densities 1333 and 2667 while their means were significantly lower for density 5333. When considering the tree descriptors, the best explanatory models of the different epicormic counts involved their relative variations, especially the relative increment (RIV) in the product V = HEIGHT.DBH 2 . More precisely, emergence of epicormic shoots occurred particularly when trees fell below a threshold value of RIV = 0.26. Such trees belonged mainly to the two highest densities: 2667 and 5333 stems/ha.• When considering only epicormics, none of the tested densities can be recommended. Trees which bear the most numerous epicormic shoots will be naturally eliminated by stand competition. epicormic shoots / plantation spacing / Quercus petraea Résumé -L'espacement à la plantation a peu d'influence sur les gourmands éphémères observés en plantation de chêne sessile âgée de 20 ans.• Les épicormiques sont des défauts importants du bois de chêne. Ils sont issus de bourgeons latents déposés très tôt sur le tronc. Ils peuvent éventuelle-ment se développer en gourmands, selon l'éclairement qui dépend de l'espacement des arbres. Dans ce contexte, nous avons étudié l'effet de la densité de plantation (1333, 2667 et 5333 tiges/ha) sur le développement des pousses épicormiques sur des chênes sessiles âgés de 20 ans.• Dans les trois densités, les pousses épicormiques ne persistent pas et sont généralement isolées. Un effet significatif mais négligeable sur la longueur des épicormiques a été observé : les pousses les plus longues sont présentes dans les densités 1333 et 2667 alors qu'elles sont plus courtes dans la densité 5333. Vis à vis des caractéristiques dendrométriques de l'arbre, les modèles les plus explicatifs des différentes variables de comptage font intervenir la variation relative RIV du produit V = H.D130 2 entre les deux campagnes. Plus précisément, en dessous d'une valeur seuil de RIV = 0,26, l'apparition des pousses épicormiques est significativement augmentée ; les arbres dans cette situation appartiennent majoritairement aux densités les plus fortes 2667 et 5333 tiges/ha.• En ne prenant en compte que les gourmands, on ne peut recommander une densité particulière. Les arbres qui portent le plus de gourmands sont les moins vigoureux ; ils seront éliminés naturellement par la compétition. pousses épicormiques...

The Response of Basal Area Increment in Old Sprout-origin Sessile Oak (Quercus petraea (Matt.) Liebl.) Trees During Their Conversion to a Coppice-with-standards

“…Our work reveals that the basal area increment is positively correlated with the number of epicormic shoots in adult sessile oak trees of sprout origin. This statement contradicts the current results that connect the epicormic shoot occurrence with radial (cambial) growth (Spiecker, 1991;Colin et al, 2008). This fi nding may be explained by the strong release of trees which until recently have been cultivated under normal (dense) canopy closure of a high forest.…”

“…From this conclusion, we may deduce that trees with smaller stem volumes have smaller diameters at breast height, which means that thinner trees produce more epicormic shoots a er thinning. Colin et al (2008) found that sessile oak trees that were cultivated from the beginning of their development in closer spacing (density) produced the longest epicormic shoots. Considering these fi ndings, it may be concluded that it is desirable to release thinner trees and cultivate them when they are as released as possible to achieve the highest basal area increment possible.…”

“…However, we must bear in mind that increased increments represent only a temporary eff ect that occurs a er thinning. One of the factors limiting this eff ect is that the trees with the highest number of epicormic shoots will be eliminated naturally (i.e., die) due to competition from the stand (Colin et al, 2008).…”

Production and role of epicormic shoots in pruned hybrid poplar: effects of clone, pruning season and intensity

“…The fewer Statistically significant values (P<0.05) are given in bold. Treatment corresponds to the combination between pruning intensity and epicormic branches treatment (1=1/3 pruned tree without epicormic shoots, 2=2/3 pruned tree without epicormic shoots, E1=1/3 pruned tree with epicormic shoots, E2=2/3 pruned tree with epicormic shoots) DF degrees of freedom epicormic shoots produced by summer-pruned trees could be explained by the fact that development of epicormic shoots depends on bud break, which occurs at the beginning of the leafy period (Harmer 1988), on light availability in early spring and on light availability throughout the growing season (Colin et al 2008). Trees pruned in fall or spring had more available light at the time of bud break and also had more time to develop epicormic buds over the growing season.…”

Tracking rameal traces in sessile oak trunks with X-ray computer tomography: biological bases, preliminary results and perspectives

“…1, 1) that occurs during stem elongation and results in one or several growth units (GU) (Fig. 1, 2) (Fontaine et al 1998;Colin et al 2008). The 50-70 axillary buds initiated per meter on average are located either at scale scar rings that separate growth units and annual shoots (LGU and LAS on Fig.…”