The Ecosystem as Super-organ/Ism, Revisited: Scaling Hydraulics to Forests under Climate Change

Authors

Jeffrey D. Wood, University of Missouri
Matteo Detto, Princeton University
Marvin Browne, Stanford University
Nathan J.B. Kraft, University of California, Los Angeles
Alexandra G. Konings, Stanford University
Joshua B. Fisher, Chapman UniversityFollow
Gregory R. Quetin, University of California, Santa Barbara
Anna T. Trugman, University of California, Santa Barbara
Troy S. Magney, University of California, Davis
Camila D. Medeiros, University of California, Los Angeles
Nidhi Vinod, University of California, Los Angeles
Thomas N. Buckley, University of California, Davis
Lawren Sack, University of California, Los Angeles

Document Type

Article

Publication Date

6-17-2024

Abstract

Classic debates in community ecology focused on the complexities of considering an ecosystem as a super-organ or organism. New consideration of such perspectives could clarify mechanisms underlying the dynamics of forest carbon dioxide (CO₂) uptake and water vapor loss, important for predicting and managing the future of Earth's ecosystems and climate system. Here, we provide a rubric for considering ecosystem traits as aggregated, systemic, or emergent, i.e., representing the ecosystem as an aggregate of its individuals, or as a metaphorical or literal super-organ or organism. We review recent approaches to scaling-up plant water relations (hydraulics) concepts developed for organs and organisms to enable and interpret measurements at ecosystem-level. We focus on three community scale versions of water relations traits that have potential to provide mechanistic insight into climate change responses of CO₂ and H₂O gas exchange and forest productivity: leaf water potential (Ψ_canopy), pressure volume curves (eco-PV), and hydraulic conductance (K_eco). These analyses can reveal additional ecosystem-scale parameters analogous to those typically quantified for leaves or plants (e.g., wilting point and hydraulic vulnerability) that may act as thresholds in forest responses to drought including growth cessation, mortality and flammability. We unite these concepts in a novel framework to predict Ψ_canopy and its approaching of critical thresholds during drought, using measurements of K_eco and eco-PV curves. We thus delineate how extension of water relations concepts from organ- and organism-scales can reveal the hydraulic constraints on the interaction of vegetation and climate, and provide new mechanistic understanding and prediction of forest water use and productivity.

Comments

This is a pre-copy-editing, author-produced PDF of an article accepted for publication in Integrative and Comparative Biology in 2024 following peer review. The definitive publisher-authenticated version is available online at https://doi.org/10.1093/icb/icae073.

Recommended Citation

Jeffrey D Wood, Matteo Detto, Marvin Browne, Nathan J B Kraft, Alexandra G Konings, Joshua B Fisher, Gregory R Quetin, Anna T Trugman, Troy S Magney, Camila D Medeiros, Nidhi Vinod, Thomas N Buckley, Lawren Sack, The Ecosystem as Super-organ/Ism, Revisited: Scaling Hydraulics to Forests under Climate Change, Integrative and Comparative Biology, 2024;, icae073, https://doi.org/10.1093/icb/icae073

Copyright

Oxford University Press