Pith: a marker of primary growth in Picea abies (L.) Karst.

Abstract

International audienceThe primary growth of trees may be studied either by following their development over time, which is costly and requires long-term monitoring, or by a posteriori growth analyses. Trees in temperate forests show rhythmic growth, which is characterised by morphological or anatomical markers. The study described here focuses on the pith of trees as an internal marker for the retrospective analysis of primary growth. Changes in pith size and density were quantified along a stem of Norway spruce [Picea abies (L.) Karst.] with high spatial resolution. The results showed that pith would appear to be a reliable marker of the annual growth rhythm even in the presence of polycyclism. Annual shoot limits were characterised by reductions in pith size associated, at the same time, with increases in pith density. In addition, pith size may provide information about tree ontogeny. The start of the competition with neighbouring trees was very likely responsible for an overall decrease in pith size. Regarding high frequency variations, pith size appeared to be less sensitive to local environmental fluctuations like climate than other studied variables such as annual shoot length and annual ring width. Finally, X-ray computed tomography proved to be a very promising method for the non-destructive detection of annual shoot limits in stems based on longitudinal changes in pith density, as demonstrated in a log of Norway spruc

Pith: a new criterion for monitoring the architecture in Mediterranean pines

“…The pith diameter measured for the last GU of the year was often close to the minimum pith diameter of the AS. These results show that the pith diameter generally decreased along the AS from the base to the top of the AS, in accordance with our hypothesis and the results of Longuetaud and Caraglio (2009) for Norway spruce. Although there were frequent exceptions for individual trees and years, this decrease could reflect the fact that GUs are preformed in the bud.…”

“…During plant life, endogenous trends in tree development have been revealed from the size and the morphology of annual shoots (Heuret et al 2006;Guédon et al 2007). Longuetaud and Caraglio (2009) highlighted the fact that pith is a good marker of primary growth in Norway spruce [Picea abies (L.) Karst.]. As pith diameter is larger at the base of the AS, it greatly helps in delimiting ASs.…”

“…Variations in stem pith size result from primary meristem activity: the alternance of extension and cessation periods. Flowering, branching and shoot mortality may be detectable from the pith size (Longuetaud and Caraglio 2009). During plant life, endogenous trends in tree development have been revealed from the size and the morphology of annual shoots (Heuret et al 2006;Guédon et al 2007).…”

Dating branch growth units in a tropical tree using morphological and anatomical markers: the case of Parkia velutina Benoist (Mimosoïdeae)

“…The limits of the GUs that make up the axes were located by recognizing markers that result from the rhythmic activity of the primary meristems, and which persist for several years in the bark and pith (Barthélémy and Caraglio 2007;Heuret et al 2000Heuret et al , 2006Nicolini et al 2001;Longuetaud and Caraglio 2009). The literature contains no information about the morphology of this species, and thus the attempt made in this section to illustrate the different expressions of primary growth in the species may be considered as original results.…”

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

“…The main challenge will be to distinguish growth unit (GU) limits within annual shoots (AS) from limits between AS (Heuret et al 2000(Heuret et al , 2003, as was successfully done on spruce logs by identifying local pith enlargement between GUs (Longuetaud and Caraglio 2009). …”