Abstract Detail



Anatomy and Morphology

Huggett, Brett [1], Wason, Jay [2], Brodersen, Craig [3].

The functional implications of the presence or absence of intervessel connections across growth rings of four northern hardwood trees.

In many trees, water transport is restricted to the current-year growth ring, however, additional transport in older growth-rings could increase the total size of the xylem network, thus increasing hydraulic redundancy but also may expose the current growth ring xylem to persistent embolisms in prior growth-rings. Efficient flow between multiple annual rings, however, would require the presence of connections between xylem conduits across the growth ring boundary, and our understanding of the frequency of cross-ring connections within a species and between species is limited, as well as potential impact water transport and drought resistance. Here we studied the annual ring boundaries in two diffuse-porous and two ring-porous trees from the eastern United States for the presence and frequency of cross ring connections using dye-staining and X-ray microcomputed tomography (microCT). We also performed hydraulic conductivity measurements to test the influence of increased connectivity resulting from cross-ring connections on water transport. Acer rubrum had multiple growth-rings of functional xylem via cross-ring intervessel connections, whereas Fagus grandifolia, Fraxinus americana, and Quercus rubra did not. For species without cross-ring connections, inclusion of multiple growth-rings in hydraulic conductivity measurements resulted in inflated maximum conductivity (Fraxinus americana, Q. rubra) or native conductivity (Fagus grandifolia). However, including multiple growth-rings did not impact hydraulic measurements for A. rubrum. In a previous study, A. rubrum was the only species of these four exhibiting vulnerability segmentation from roots-to-shoots, which may be correlated with cross-ring intervessel connections and multiple growth-rings of functional xylem. The presence of cross-ring intervessel connections, therefore, may be an important trait that can help explain aspects of whole-tree water transport and should be carefully considered when conducting plant hydraulic studies.


1 - Bates College, Biology, 44 Campus Ave., Lewiston, ME, 04240, United States
2 - Yale University, School of Forestry and Environmental Studies, 370 Prospect St., New Haven , CT, 06511, USA
3 - Yale University, School Of Forestry & Environmental Studies, 195 Prospect Street, Kroon Hall, New Haven, CT, 06511, United States

Keywords:
Acer rubrum
Fagus grandifolia
Fraxinus americana
Quercus rubra
xylem
embolism.

Presentation Type: Poster
Number: PAM005
Abstract ID:267
Candidate for Awards:None


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