COS 145-6 - CANCELLED - Insights on carbon allocation to wood in Silver fir revealed by monitoring of wood cell formation, isotopic signature of tree-ring cellulose and ecophysiological modelling

Wednesday, August 17, 2022

11:15 AM – 11:30 AM EDT

Location: 515B

Presenting Author(s)

FG

Fabio Gennaretti

Institut de recherche sur les forêts | UQAT, Canada

Coauthor(s)

GP

Gonzalo Perez de Lis

Universidade de Santiago de Compostela, Spain
LF

Laura Fernandez de Uña

CREAF, Spain
MC

Matthias Cuntz

INRAE Grand Est - Nancy, France
JO

Jérôme Ogée

INRAE Centre de Bordeaux Aquitaine, France
LW

Lisa Wingate

INRAE Centre de Bordeaux Aquitaine, France
SP

Stéphane Ponton

INRAE Grand Est - Nancy, France
CR

Cyrille Rathgeber

INRAE Grand Est - Nancy, France

Background/Question/Methods

The use of multiple data from tree-rings, including isotopic ratios and xylogenesis monitoring, can enhance our interpretations on tree functioning and on tree-environment relations. Here, we explored whether understanding of carbon deposition to tree-rings could be improved using: (1) monitoring of wood cell formation during the growing season, (2) intra-annual data of δ¹³C in tree-ring cellulose and (3) ecophysiological modelling. We collected wood micro-cores to monitor wood cell formation of six Silver fir trees at two forest sites in the Vosges mountains (France) and detect periods of cell division, cell enlargement and cell wall thickening of 10 tree-ring subsectors per year over three years (2007-2009). The same trees were sampled to measure δ¹³C of tree-ring cellulose (δ¹³Ccell) over similar 10 tree-ring subsectors of the same three years. We then used an ecosystem model, integrating a model for sugar availability and carbon isotope fractionation, to identify periods of carbon deposition in each tree-ring subsector based on the agreement between simulated and observed δ¹³Ccell values.

Results/Conclusions

Our results show how intra-annual patterns of ¹³C/¹²C ratios of tree-ring cellulose were driven by vapor pressure deficit variations over the growing season and that cellulose deposited in the tree-ring subsectors integrated carbon that started to be assimilated in the cells during the cell division phase and before the cell enlargement and wall thickening. This means that there is a time delay between the environmental forcing and the isotopic signature of tree-rings. Our study provides useful insights on carbon allocation to wood in Silver fir that can be used to improve interpretations of isotopic time series of this species.