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Coupled whole-tree optimality and xylem-hydraulics explain dynamic biomass partitioning

Potkay, Aaron and Trugman, Anna T. and Wang, Yujie and Venturas, Martin D. and Anderegg, William R. L. and Mattos, Caio R. C. and Fan, Ying (2021) Coupled whole-tree optimality and xylem-hydraulics explain dynamic biomass partitioning. New Phytologist, 230 (6). pp. 2226-2245. ISSN 0028-646X. doi:10.1111/nph.17242.

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Trees partition biomass in response to resource limitation and physiological activity. It is presumed that these strategies evolved to optimize some measure of fitness. If the optimization criterion can be specified, then allometry can be modeled from first principles without prescribed parameterization. We present the Tree Hydraulics and Optimal Resource Partitioning (THORP) model, which optimizes allometry by estimating allocation fractions to organs as proportional to their ratio of marginal gain to marginal cost, where gain is net canopy photosynthesis rate, and costs are senescence rates. Root total biomass and profile shape are predicted simultaneously by a unified optimization. Optimal partitioning is solved by a numerically efficient analytical solution. THORP’s predictions agree with reported tree biomass partitioning in response to size, water limitations, elevated CO₂ and pruning. Roots were sensitive to soil moisture profiles and grew down to the groundwater table when present. Groundwater buffered against water stress regardless of meteorology, stabilizing allometry and root profiles as deep as c. 30 m. Much of plant allometry can be explained by hydraulic considerations. However, nutrient limitations cannot be fully ignored. Rooting mass and profiles were synchronized with hydrological conditions and groundwater even at considerable depths, illustrating that the below ground shapes whole-tree allometry.

Item Type:Article
Related URLs:
URLURL TypeDescription
Potkay, Aaron0000-0003-3101-2701
Trugman, Anna T.0000-0002-7903-9711
Wang, Yujie0000-0002-3729-2743
Venturas, Martin D.0000-0001-5972-9064
Additional Information:© 2021 The Authors. New Phytologist © 2021 New Phytologist Foundation. Issue Online: 17 May 2021; Version of Record online: 27 March 2021; Accepted manuscript online: 01 February 2021; Manuscript accepted: 25 January 2021; Manuscript received: 23 July 2020. Research Funding: NSF. Grant Numbers: EAR-1528298, AGS-1852707.
Funding AgencyGrant Number
Subject Keywords:carbon allocation; CO2 enrichment; groundwater; hydraulic limitations; optimality; stomatal control; tree allometry; tree drought responses
Issue or Number:6
Record Number:CaltechAUTHORS:20210202-065754609
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Official Citation:Potkay, A., Trugman, A.T., Wang, Y., Venturas, M.D., Anderegg, W.R.L., Mattos, C.R.C. and Fan, Y. (2021), Coupled whole-tree optimality and xylem hydraulics explain dynamic biomass partitioning. New Phytol, 230: 2226-2245.
Usage Policy:No commercial reproduction, distribution, display or performance rights in this work are provided.
ID Code:107843
Deposited By: Tony Diaz
Deposited On:02 Feb 2021 16:36
Last Modified:26 May 2021 18:50

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