INSTITUTO ARGENTINO DE NIVOLOGIA, GLACIOLOGIA Y CIENCIAS AMBIENTALES
Unidad Ejecutora - UE
congresos y reuniones científicas
Fire-induced changes in Nothofagus pumilio wood anatomy
VILLALBA, R.; STOFFEL, M.; GONZÁLEZ, C.V.; MUNDO, I.A.; BALLESTEROS-CÁNOVAS, J.A.
Conferencia; AmeriDendro 2016 - Third American Dendrochronology Conference; 2016
Fire is one of the most important disturbance agents in Patagonia. Fire histories have been reconstructed from different species using dendrochronological methods. However, little is known about the wood anatomy of fire scars. In this study, anatomical and hydraulic characteristics of Nothofagus pumilio fire-scarred cross sections from southern Patagonia, Argentina, were evaluated. Transverse microsections were cut from scarred fire cross sections for light microscopy. Anatomical and hydraulic parameters were measured in five successive rings at radial distances of 0 and 45 degrees from the callus and for 1-mm wide bands using image analysis; resulting in a total of 115 ring portions analyzed. General linear mixed effect models (glmm) were adjusted to analyze the significance of the temporal and spatial differences in average vessel lumen area (AVLA), percentage of vessel lumen area (PVLA), average vessel lumen diameter (AVLD), vessel density (VD), xylem relative conductivity (REC) and xylem vulnerability index (VUL). At the 0 degree position, significant differences in the analyzed parameters were observed between the control rings, fire ring and post-fire rings (temporal effect). For fire rings, a significant decrease in AVLA, PVLA, and VD was observed; which was associated with a highly significant decrease in REC. Furthermore, in fire rings an increase in the number of rays was observed. In the case of PVLA, VD and REC variables, the significant decrease was not only confined to the fire ring, but it also lasted until two years after the injure occurrence. In terms of distance, differences in AVLA, PVLA REC and radii number were observed mainly in a short distance from the callus (mainly in the 1st 1mm-width band) indicating an punctual effect of fires in cambium activity close the scar. These temporal modifications in wood anatomical parameters induced by fire wounding might be indicating the physiological requirement to secure xylem hydraulic conductivity and mechanical resistance.