When tree rings behave like foam: moderate historical decrease in the mean ring density of common beech paralleling a strong historical growth increase

Abstract

International audienceContext. While historical increases in forest growth have been largely documented, investigations on historical wood density changes remain anecdotic. They suggest possible density decreases in softwoods and ring-porous hardwoods, but are lacking for diffuse-porous hardwoods. Aims. To evaluate the historical change in mean ring density of common beech, in a regional context where a ring-porous hardwood and a softwood have been studied, and assess the additional effect of past historical increases in radial growth (+50% over 100 years), resulting from the existence of a positive ring size-density relationship in broadleaved species. Methods. 74 trees in 28 stands were sampled in Northeastern France to accurately separate developmental stage and historical signals in ring attributes. First, the historical change in mean ring density at 1.30m (X-ray microdensitometry) was estimated statistically, at constant developmental stage and ring width. The effect of past growth increases was then added to assess the net historical change in wood density. Results. A progressive centennial decrease in mean ring density of -55kg.m-3 (-7.5%) was identified (-10% following the most recent decline). The centennial growth increase induced a maximum +25kg.m-3 increase in mean ring density, whose net variation thus remained negative (-30kg.m-3). Conclusions. This finding of a moderate but significant decrease in wood density that exceeds the effect of the positive growth change extends earlier reports obtained on other wood patterns in a same regional context and elsewhere. Despite their origin is not understood, such decreases hence form an issue for forest carbon accounting

Variability of European beech wood density as influenced by interactions between tree-ring growth and aspect

“…Our results are confirmed by Zhang (1995) who observed only a little influence of growth rate on specific gravity and mechanical proprieties of other diffuse-porous tree species (birch and poplar). Likewise, Bontemps et al (2013) Fig. 5 Contour plot visualising the wood density variation with tree-ring width per aspect Fig.…”

“…The relationship between tree-ring width and tree-ring density has been intensively studied and it varies according to tree species (Bontemps et al 2013). For instance for spruce an increase in tree-ring width was found to decrease wood density (Mäkinen et al 2007;Piispanen et al 2014;Franceschini et al 2010), while for oak Guilley et al (2004) found that an increase in tree-ring width results in an increase in wood density.…”

“…Studies which link wood density to tree-ring width, cambial age, different environmental factors or silvicultural practices were mostly carried out for conifer species (Cregg et al 1988;Jozsa and Brix 1989;Bouriaud et al 2005;Filipescu et al 2014). For broadleaves, due to the vessel distribution within the tree-rings, these studies are limited to ring porous tree species (Bergès et al 2008;Guilley et al 1999); wood density variation of diffuse-porous tree species has rarely been analysed (Zhang 1995;Bouriaud et al 2004;Skomarkova et al 2006;Bontemps et al 2013).…”

Patterns of within-stem variations in wood specific gravity and water content for five temperate tree species

“…Other studies have reported a radial decrease in density for this species. For example, Bontemps et al (2013) observed a general slow decreasing trend of mean ring specific gravity with increasing ring number when the 20 first growth rings were removed from the dataset. For this species, contradictory results were previously obtained, showing either higher or lower density in juvenile wood compared with mature wood (Nepveu 1981), whereas, for Quercus sp., the radial decrease in BSG from pith to bark is well-known (e.g.…”

Growth Characteristics and Tree-Ring Width Response of Quercus acutissima to Climate Factors in the Rocky Mountain Area of Northern China

“…Tree rings have characteristics that include accurate dating ability, strong continuity, and high resolution, and have been widely used in research on climate change response for a long time [4][5]. Tree rings not only record the age of trees but also the climate changes that occurred in the past, and the close relationship between climate factors and tree-ring width can also be used to determine future patterns of tree growth in the context of climate change [6][7][8]. The formation of annual tree rings in the growth process is affected by many climate factors in both the current and previous years, and these factors are particularly important for the formation and growth of tree rings [9][10][11].…”