Global variation in the ratio of sapwood to leaf area explained by optimality principles

Xu, H., Wang, H., Prentice, I. C., Harrison, S. P. ORCID: https://orcid.org/0000-0001-5687-1903, Rowland, L., Mencuccini, M., Sanchez-Martinez, P., He, P., Wright, I. J., Sitch, S., Li, M. and Ye, Q. (2026) Global variation in the ratio of sapwood to leaf area explained by optimality principles. New Phytologist, 250 (1). pp. 181-193. ISSN 1469-8137 doi: 10.1111/nph.70916

Abstract/Summary

The sapwood area supporting a given leaf area (Huber value, vH) reflects the coupling between carbon uptake and water transport and loss at a whole-plant level. Geographic variation in vH presumably reflects plant strategic adaptations, but the lack of a general explanation for such variation hinders its representation in vegetation models and assessment of its impact on the global carbon and water cycles. Here we develop a simple hydraulic trait model to predict optimal vH by matching stem water supply and leaf water loss, and test its performance against two extensive plant hydraulic datasets. We show that our eco-evolutionary optimality-based model explains nearly 60% of global vH variation in response to light, vapour pressure deficit, temperature and sapwood conductivity. Enhanced hydraulic efficiency with warmer temperatures reduces the sapwood area required to support a given leaf area, whereas high irradiance (supporting increased photosynthetic capacity) and drier air increase it. This study thus provides a route to modelling variation in functional traits through the coordination of carbon uptake and water transport processes.

Item Type	Article
URI	https://centaur.reading.ac.uk/id/eprint/129454
Identification Number/DOI	10.1111/nph.70916
Refereed	Yes
Divisions	Science > School of Archaeology, Geography and Environmental Science > Department of Geography and Environmental Science
Publisher	Wiley
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