INSTITUTO ARGENTINO DE NIVOLOGIA, GLACIOLOGIA Y CIENCIAS AMBIENTALES
Unidad Ejecutora - UE
congresos y reuniones científicas
Variation in wood anatomical traits: a tentative explanation of the functional significance of wood parenchyma in a desert plant.
ROIG JUÑENT FA; GIANTOMASI MA
Encuentro; 2012 IAWA Pan-American Meeting; 2012
IAWA, FEPAF, UNESP
Wood anatomical traits in dated long tree-ring records have proven to be useful data for ecological interpretations. However, most of these studies have been based on transverse vessel size or area, while little is known about the applicability or function of other xylem components, such as wood parenchyma. New inter-annual wood anatomy data, from a semi-desert tree of the central plains of Argentina, offer insights into parenchyma tissue formation, its relationship with vessel surface, and how its growth depends on specific climate factors. Cross-matched series of annual tree-ring areas were compared against annual-resolution data for vessel areas and parenchyma, which resulted in correlations of 0.74 and 0.79, respectively (p<0.01, n = 608). This implies a close relationship between the entire growth ring and the wood portions associated with vessels and parenchyma tissues. Moreover, the comparison between vessel and parenchyma areas resulted in even higher correlations (r = 0.96, p<0.001, n = 608), implying a direct link between these two variables. Comparisons between regional climate and wood anatomy data show positive and statistically significant correlations between vessels, parenchyma, and rains occurring during the initial stages of ring formation, as well as negative correlations with air temperatures recorded at the same time. This is the basis for a climate-plant growth model for a low dryland tree. In the analyzed samples, xylem parenchyma is abundant and almost completely surrounds every vessel. Consequently, there are few contact faces between vessels, the great majority of which face xylem parenchyma cells. The role of parenchyma in the hydraulic function of xylem has been hypothesized to be associated with long-distance water transport and refilling of embolized conduits. Wood anatomy we analyzed necessarily implies that vessels must be functionally related to the surrounding parenchyma. We argue this parenchyma tissue, proportionally sized to vessel area and linked to seasonal climate variations, may be considered as a subsidiary conductive system that take over the role of water-conduction pathways when fluid movements in vessels is disrupted.