Abstract Detail

100 years of Baileyan Trends – Wood Evolution, Function and Future

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

Three dimensional xylem organization and its implications for water transport during drought.

Increasing intensity and return frequency of drought may expose many tree species to stress levels beyond their physiological thresholds. One critical mechanism underlying tree mortality is failure of the hydraulic system. Xylem vessel networks are vulnerable to the formation and spread of gas-embolisms during drought that interrupt water transport. Xylem resistance to drought is often characterized by measuring the percent loss of conductivity (PLC) for a given degree of water stress. The shape of this PLC curve, and thus the xylem network’s resistance to the spread of embolisms, is primarily driven by the air-seeding threshold of the pit membranes that separate individual vessels, and the connectivity of the xylem network. Xylem network parameters, however, are difficult to measure because of the inherent complexity of wood. To better understand how xylem networks are structured, and how the organization of xylem conduits translates to hyraulic performance under a range of conditions, we used high-resolution X-ray computed micro-tomography (microCT) imaging to study four North American hardwood tree species, and different tissue types. We digitally extracted xylem network parameters from our samples (pit field fraction, total pit area, number and frequency of intervessel connections, etc.) and then developed a custom software package to model network performance under a range of conditions. The xylem networks are extremely sensitive to the initial conditions, and increasing connectivity between vessels across the network leads to greater risk of systemic spread, and the hydraulic segmentation of different tissue types (e.g. roots and petioles) leads to significant differences in network performance. The modeled PLC curves showed good agreement with empirical methods, and represent a significant advance in our understanding of the relationships between the structure and function of plant vascular systems.

1 - Yale University, School Of Forestry & Environmental Studies, 195 Prospect Street, Kroon Hall, New Haven, CT, 06511, United States
2 - Yale University, School Of Forestry & Environmental Studies, 195 Prospect Street, New Haven, CT, 06511, US
3 - Bates College, Biodlogy, 44 Campus Ave, Lewiston , ME, 04240, United States

none specified

Presentation Type: Colloquium Presentations
Abstract ID:89
Candidate for Awards:None

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