Gamma Rays Signal the Vulnerability of Forest to Extreme Drought

Gavan S. McGrath; Joseph B. Fontaine; Richard Van Dongen; Katinka X. Ruthrof

doi:10.1029/2026GL122182

Back

Gamma Rays Signal the Vulnerability of Forest to Extreme Drought

Letter/Communication

Open access

Peer reviewed

Gamma Rays Signal the Vulnerability of Forest to Extreme Drought

Gavan S. McGrath, Joseph B. Fontaine, Richard Van Dongen and Katinka X. Ruthrof

Geophysical research letters, Vol.53(15), e2026GL122182

2026

DOI: https://doi.org/10.1029/2026GL122182

Files and links (1)

pdf

Published11.70 MBDownload View

Open Access CC BY V4.0

Abstract

Geology

Geosciences, Multidisciplinary

Physical Sciences

Science & Technology

Extreme drought and heat are driving forest die-off globally, yet regional-scale mapping of subsurface water storage capacity, governing forest vulnerability, remains a major challenge. Here, we demonstrate that airborne gamma-ray spectrometry (GRS) of potassium (40K) decay provides a powerful proxy for subsurface constraints on water availability. In southwestern Australia, we found that spatial patterns of forest die-off during an extreme 2023-2024 drought-heat event were strongly predicted by surficial 40K concentrations. While GRS measures the upper similar to 30 cm of soil, plot-scale electrical resistivity tomography suggests that elevated 40K signals shallow granite or gneiss bedrock, to depths reaching several tens of meters due to leaching of mobile elements, remnant bedrock minerals, erosional thinning of regolith and biological nutrient recycling from K-rich saprolite. Airborne GRS can map forest vulnerability across highly leached landscapes, which cover one-third of Earth's ice-free land surface. This enables targeted adaptive management of forests for future drought-heat intensification.

Details

Title: Gamma Rays Signal the Vulnerability of Forest to Extreme Drought
Authors/Creators: Gavan S. McGrath - The University of Western Australia
Joseph B. Fontaine - Murdoch University
Richard Van Dongen - Department of Biodiversity, Conservation and Attractions
Katinka X. Ruthrof - Department of Biodiversity, Conservation and Attractions
Publication Details: Geophysical research letters, Vol.53(15), e2026GL122182
Publisher: Wiley Periodicals LLC on behalf of American Geophysical Union.
Number of pages: 9
Grant note: Department of Biodiversity Conservation and Attractions
Identifiers: 991005909768507891
Murdoch Affiliation: School of Environmental and Conservation Sciences
Language: English
Resource Type: Letter/Communication

Metrics

1 Record Views