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Global estimates of the storage and transit time of water through vegetation

Published Article

Global

Publication date: January 9, 2025

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Water’s journey through vegetation is a rapid but understudied part of the hydrologic cycle. Using five years of satellite observations, this study estimates global vegetation water storage at ~484 km³, half of it in water‑limited savannas, grasslands and shrublands. Combining storage with remotely sensed transpiration reveals mean transit times ranging from ~5 days in croplands to ~18 days in evergreen needleleaf forests, with a global median of 8.1 days. In herbaceous systems, water may cycle through biomass in less than a day. These findings show that vegetation water transit is among the fastest hydrologic processes and clarify the role of plants in linking weather, climate and ecosystem function.

Subject Tags

  • Life Sciences
  • Savanna
  • Grassland

Abstract

The time it takes for water to transit from the ground back to the atmosphere affects weather, climate, biogeochemistry and ecosystem function. The transit time of water through vegetation, defined as the age of water transpiring from vegetation since time of entry, is a particularly understudied aspect of the terrestrial hydrologic cycle. Here we use a synergy of satellite remote sensing measurements over a five-year period to estimate global aboveground vegetation water storage to be on average 484 km3, roughly half of which is stored in Earth’s water-limited savannah, grassland and shrubland ecosystems. We then combine these storage estimates with remotely sensed data for transpiration and find that mean transit times of water through aboveground vegetation vary from ~5 days in croplands to ~18 days in evergreen needleleaf forests, with a global median of 8.1 days. In herbaceous-dominated land-cover types with comparatively low water storage and high seasonal water use, such as grasslands, the water stored in biomass may be frequently transiting in less than one day. Our estimates contribute to resolving the role of vegetation in the terrestrial hydrologic cycle; plants store little water compared to other pools, and the time it takes to return that water to the atmosphere is among the fastest components of the hydrologic cycle.

Citation

Felton, A. J., Fisher, J. B., Hufkens, K., Purdy, A. J., Spawn-Lee, S. A., Duloisy, L. F., & Goldsmith, G. R. (2025). Global estimates of the storage and transit time of water through vegetation. Nature Water, 3(1), 59-69. https://doi.org/10.1038/s44221-024-00365-9

TNC Authors