Transport in a coordinated soil-root-xylem-phloem leaf system
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2018-09
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© 2018 Elsevier Ltd Links between the carbon and water economies of plants are coupled by combining the biochemical demand for atmospheric CO2with gas transfer through stomates, liquid water transport in the soil-xylem hydraulic system and sucrose export in the phloem. We formulated a model to predict stomatal conductance (gs), consistent with the maximum energy circulation concept of Lotka and Odum, by maximizing the sucrose flux out of photosynthesizing leaves. The proposed modeling approach recovers all prior results derived from stomatal optimization theories and profit-maximization arguments for the xylem hydraulic system aimed at predicting gs. The novel features of this approach are its ability to 1) predict the price of losing water in carbon units using xylem and phloem properties (i.e., the marginal water use efficiency) and 2) explain why water molecules become more expensive to exchange for CO2molecules when soil moisture becomes limiting or when plants acclimate to new elevated atmospheric CO2concentration. On short time-scales (sub-daily), predicted gsunder many environmental stimuli were consistent with measurements reported in the literature, including a general sensitivity of gsto vapor pressure deficit and leaf water potential. During progressive droughts, differences in the coordination among the leaf, xylem, and phloem functioning determine the isohydric-to-anisohydric behavior among plants.
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Huang, CW, JC Domec, S Palmroth, WT Pockman, ME Litvak and GG Katul (2018). Transport in a coordinated soil-root-xylem-phloem leaf system. Advances in Water Resources, 119. pp. 1–16. 10.1016/j.advwatres.2018.06.002 Retrieved from https://hdl.handle.net/10161/17324.
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Scholars@Duke
Jean Christophe Domec
Bordeaux Sciences Agro in FRANCE (primary appointment)
Discovery of knowledge in Plant water relations, ecosystem ecology and ecohydrology, with special focus on: - Long-distance water transport under future climate; - Drought tolerance and avoidance; - Patterns of changes in structural and functional traits within individual plants. My goal as a researcher is to improve the fundamental science understanding of how plants and terrestrial ecosystems respond to climate changes, and to provide tree breeders with policy-relevant information. I have carried out research on interactions between soil water and plant water use in contrasting ecosystems, in cooperation with scientists at Bordeaux Sciences Agro in FRANCE (primary appointment), Duke University, Oregon State University, and the USDA Forest Service, Southern Global Change Program, recently renamed EFETAC (Eastern Forest Environmental Threat Assessment Center).
Sari Palmroth
Dr. Palmroth's research focuses on the effects of resource availability and climatic variability on carbon uptake and allocation of individual shoots, trees and forest ecosystems. She studies ecophysiological processes in trees from leaf to stand scales, with special emphasis on conifers. In particular, Dr. Palmroth is interested in the radiative transfer in forest canopies, how the radiation regime is affected by conifer shoot structure, and what the feedbacks are between availability of solar energy and allocation on carbon and nitrogen within canopies. She is also interested in how the carbon fixed in photosynthesis is allocated between above and belowground pools and what are the possible interaction effects on the allocation of the availabilities of nutrients and water and the level of atmospheric [CO2].
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