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

• Published in: Annals of forest science. Vol. 70; no. 4; pp. 329 - 343
• Main Authors: Bontemps, Jean-Daniel, Gelhaye, Pierre, Nepveu, Gérard, Hervé, Jean-Christophe
• Format: Journal Article
• Language: English
• Published: Paris Springer-Verlag 01-06-2013; EDP Sciences; Springer Nature (since 2011)/EDP Science (until 2010)
• Subjects: accounting; Agricultural sciences; Biodiversity and Ecology; Biological and medical sciences; Biomedical and Life Sciences; carbon; Ecology, environment; Ecosystems; Environment; Environmental Sciences; Fagus; forest growth; Forestry; Forestry Management; forests; Fundamental and applied biological sciences. Psychology; Global Changes; growth rings; hardwood; Life Sciences; Original Paper; Silviculture, forestry; softwood; Tree Biology; trees; wood density; Wood Science & Technology; X-radiation; France; Ring width; Historical change; Growth change; Wood density; X-ray microdensitometry; Wood; Microdensitometry; X ray; Fagaceae; Density; Case history; Tree ring; Dicotyledones; Angiospermae; Forestry; Hardwood forest tree; Spermatophyta; Fagus sylvatica; growth change; ring width; wood density; historical change
• ISSN: 1286-4560; 1297-966X
• DOI: 10.1007/s13595-013-0263-2

• CONTEXT : 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 : Seventy-four 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 1.30 m (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 −55 kg m⁻³ (−7.5 %) was identified (−10 % following the most recent decline). The centennial growth increase induced a maximum +25 kg m⁻³ increase in mean ring density, whose net variation thus remained negative (−30 kg 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 not being understood, such decreases hence form an issue for forest carbon accounting.