The effects of thinning and gypsy moth defoliation on wood volume growth in oaks

Abstract

Stem dissection and dendroecological methods were used to examine the effects of thinning and defoliation by gypsy moth (Lymantria dispar L.) on wood volume increment in oaks (Quercus rubra L., Q. alba L., Q. prinus L.). A model was developed to evaluate radial volume increment growth at three time periods: before defoliation, during defoliation and after defoliation, as a function of species, defoliation intensity and crown position. Volume increment during these same time periods was also compared at different stem locations. Trees were defoliated for two consecutive years and results indicated that volume loss was greater during the second year of defoliation with complete recovery taking 2-3 years after defoliation. Oaks in thinned stands had similar reductions in annual volume increment during defoliation as those in the unthinned stand. Annual volume increment demonstrated a decreasing trend from stump to base of the live crown and volume increment of the lowest log (from stump height to 1.37 m), was always higher than upper log sections, even during defoliation. Both earlywood and latewood increments were reduced during defoliation; however, latewood reductions were distributed along entire stems while earlywood reductions were greater on upper stem sections within the crown.

Exploring Growth Variability and Crown Vitality of Sessile Oak (Quercus Petraea) in the Czech Republic

“…Increased abundance of Tortrix viridiana was also found in the first half of the 1990s; however, the caterpillars caused only low amounts of defoliation. The defoliation of oaks due to caterpillars may lead to a reduction in radial growth (Fajvan et al, 2008); however, we suppose that the effect of caterpillar feeding on this stand was not significant because the abundance of Tortrix was only slightly increased. The stress load of past years is reflected in the presence of dry branches in the central part of the crowns of all of the trees examined.…”

The anatomical traits of trunk wood and their relevance to oak (Quercus robur L.) vitality

“…The authors postulated that modifications in the structure of conductive elements were caused by fungi belonging to Ceratocystis genus, which resulted in wood dysfunction. In the case of oaks from Krotoszyn, it could be also defoliation, which is known as a factor altering the water transport due to the fact that the lumen of its vessels was filled with tyloses (Fajvan et al 2008).…”

Modelling natural disturbances in forest ecosystems: a review

“…Forest management, manipulating the latter aspects, significantly affects the susceptibility to insect pests (e.g., Veteli et al, 2006;Fajvan et al, 2008;Jactel et al, 2009). The potential influence of vegetation attributes is best illustrated by tree-based classifications according to a set of discriminating variables, often including stand basal area or specific tree properties (Reynolds and Holsten, 1996;Negrón and Popp, 2004).…”