Composition, distribution and supposed origin of mineral inclusions in sessile oak wood — consequences for microdensitometrical analysis

Abstract

-SEM and light-microscopical observations, supported by chemical microanalysis with an EDXA system, revealed that light-saturated pixels observed in X-ray negatives of sessile oak (Quercus petraea Liebl.) wood were caused by inorganic deposits present inside multiseriate ray and axial parenchyma cells. Calcium oxalate crystals, silica grains and amorphous granules with varied mineral compositions have been identified. The wood strips of three out of six sampled trees contained measurable amounts of mineral inclusions which were quantified using image analysis. Based on the variations of mineral content observed between trees and within and between annual rings of the same tree, some hypotheses were formulated concerning the factors involved in the formation of inorganic deposits in oak wood. Their occurrence varies depending on the mineral concerned and seems to be controlled largely by a tree effect. The time of formation appears to coincide with a shifting of the oak wood's functions as a result of heartwood formation processes (inter-annual scale) or changes in leaf phenology and climate (intra-annual scale). In addition, the technical consequences of their presence as well as their effects on wood density measurements through microdensitometry are discussed.Quercus / mineral deposits / microdensitometry / image analysis / dendro-ecology Résumé -Composition, distribution et origine supposée d'inclusions minérales dans le bois de chêne sessile -conséquences pour l'analyse microdensitométrique. Des observations à l'aide de microscopes électronique à balayage et optique, appuyées par des analyses élémentaires au moyen d'un système EDXA, ont révélé que les points-images saturés en niveau de gris, constatés dans les négatifs de radiographies de bois de chêne sessile (Quercus petraea Liebl.), étaient dus à des dépôts inorganiques présents à l'intérieur des cellules parenchymateuses des rayons ligneux multisériés et du parenchyme axial. Des cristaux d'oxalate de calcium, des grains de silice et des granules amorphes ayant des compositions minérales variées ont été identifiés. Des barrettes de trois sur six arbres échantillonnés contenaient des quantités mesurables d'inclusions minérales qui ont été quantifiées par analyse d'images. En se basant sur les variations du contenu en dépôts minéraux observées entre arbres ainsi qu'à l'intérieur d'un arbre, aux niveaux intra-et intercerne, quelques hypothèses ont été avancées concernant les facteurs potentiellement responsables de la formation de dépôts minéraux chez le chêne. Leur présence dépend du minéral concerné et semble être contrôlée par un fort effet arbre. L'apparition des minéraux coïncide apparemment avec des changements de fonctions du bois relatifs aux processus de duraminisation (échelle interannuelle) ou correspondant à des évolutions phénologiques ou climatiques (échelle intra-annuelle). Enfin, les conséquences techniques ainsi que les effets de leur présence sur des mesures de la densité du bois par analyse microdensitométrique sont discutés.Querc...

The polymorphic weddellite crystals in three species of Cephalocereus (Cactaceae)

“…Nevertheless, the morphological diversity must be related to the elemental composition because crystalline structures may be modified when other elements become part of the molecules (De Yoreo and Dove, 2004). The Ca concentration in weddellite for the three species was over 80%, almost four times greater than quantities reported for mono-and dihydrated Ca (webmineral, 2014), and greater than the 21.67% of Ca reported in Quercus petraea wood, which is classified as trihydrate (Vansteenkiste et al, 2007). This finding is significant because the soils where the species grow do not have significant quantities of soluble Ca (Bárcenas-Argüello et al, 2010).…”

“…Concerning morphology, biogenic minerals frequently differ significantly from inorganic minerals (Lowenstam and Weiner, 1989) and may have different crystal structures when other elements become part of the crystal molecules (De Yoreo and Dove, 2004;Ward, 2005). Biogenic minerals have different forms and hydration states, allowing them to be used as taxonomic or phylogenetic characters (Franceschi and Nakata, 2005;Horner et al, 2009;Lersten and Horner, 2000, 2006, 2008Prychid et al, 2003;Vansteenkiste et al, 2007).…”

Dendrochemical patterns of calcium, zinc, and potassium related to internal factors detected by energy dispersive X-ray fluorescence (EDXRF)

“…The flecks as measured using the 50-lm traverse increments in Itrax are also similar in size to those previously reported. Smaller calcium crystals were also observed in radiograms of pedunculate oak (Quercus robur, also known as Q. pedunculata) and attributed to calcium oxalate on the basis of crystal shape (Vansteenkiste et al, 2007). Calcium oxalate is one of the most common biominerals in forest vegetation and forest soils, produced by both plants and fungi (Verrechia et al, 2006;Smith et al, 2009) and observed in poplar (Todeschini et al, 2011).…”

High-resolution densitometry and elemental analysis of tropical wood

“…Since primary cell walls have higher concentrations of pectins than secondary walls (Sarkar et al 2009 ), cell types with thick secondary walls such as fibers should have a lower proportion of pectins and cations binding to these than thin-walled parenchyma cells. Mineral inclusions in wood have high concentrations of specific elements, they are not distributed uniformly and can be seen in micro-density measurements (Vansteenkiste et al 2007 ) and chemically analyzed by energy-dispersive X-ray fluorescence (Smith et al 2014 ). The concentration of nutrients essential for the functioning of living cells will depend on the proportion of living (parenchyma) cells in wood, which often decreases from the cambium onwards and is zero in heartwood.…”