Plant water storage optimality across hydroclimatic landscapes

A quantification of the mechanisms underlying plant water use strategies is central to understanding plant stress vulnerability, productivity, and subsequent responses to hydroclimatic shifts. To explore such dynamics, we developed a dynamical model for the changes of internal plant water storage (PWS) and soil moisture given a set of coupled balance equations. This trade-off was explored through the analysis of long-term plant fluxes over a range of climate regimes, providing constraints on water availability and demand while incorporating plant physiological mechanisms into the model framework. In conjunction, plant productivity was considered, taken as the plant carbon dioxide assimilation with an additional maintenance cost subtracted to account for varying internal plant water capacities. We began by developing a conceptual model by linearizing the resulting set of coupled ordinary differential equations (ODEs) for PWS and soil moisture to obtain the plant’s long-term response to changing rainfall frequencies. The conceptual model produced clear PWS optima that decreased nonlinearly with increasing rainfall frequency, as plants with a higher PWS capacity maintained a higher minimum internal water storage overall. The model was then extended to include nonlinear components, including stochastic rainfall forcing. Under time-averaged conditions, due to the cost associated with plant size along with the timescale of intake and water release, we found that net carbon uptake does not necessarily increase with larger maximum PWS capacities but is sustained for longer periods during drought due to transpiration being facilitated by internal water stores. This reduces stress for water storing plants in climate regimes with high intensity, low frequency precipitation. Increased rainfall frequency and a decrease in intensity greatly reduce the overall optimal PWS capacity, even when overall water availability is changed. Thus, the extended model confirms that optimal PWS decreases nonlinearly as the rainfall becomes more frequent and less intense, as in the conceptual model. This suggests that water storage plays a less critical role in wet environments that may show an increase in wet days, but not necessarily an increase in water availability. We then analyzed remote sensing data trends in seasonally dry ecosystems and compared them with the nonlinear point process model to identify physically based mechanisms governing plant water use, incorporating plant functional traits potentially coordinated with PWS. Supplementary Material File (plant_water_storage_optimality_across_hydroclimatic_landscapes_final_draft (7).pdf) - Download - 4.45 MB Information & Authors Information Version history Peer review timeline Published Ecohydrology Version of Record27 Aug 2025Published Copyright This work is licensed under a Non Exclusive No Reuse License. Collection

Authors Metrics & Citations Metrics Article Usage 628views 201downloads Citations Download citation Elizabeth Cultra, Mark S. Bartlett, Amilcare Porporato. Plant water storage optimality across hydroclimatic landscapes. Authorea. 20 March 2025. DOI: https://doi.org/10.22541/au.174244518.84758553/v1 DOI: https://doi.org/10.22541/au.174244518.84758553/v1 If you have the appropriate software installed, you can download article citation data to the citation manager of your choice. Simply select your manager software from the list below and click Download. For more information or tips please see 'Downloading to a citation manager' in the Help menu.