Ground-based GNSS transmissometry reveals contrasting leaf and stem water dynamics in a central Amazon rainforest

Year: 2026

Type: article

Abstract: Vegetation optical depth (VOD) is widely used to monitor vegetation water dynamics, yet its interpretation in dense tropical forests remains uncertain because independent observations of water partitioning among vegetation compartments are scarce. Here, we compare Global Navigation Satellite System transmissometry-derived VOD (GNSS-T VOD) with independent measurements of leaf, stem, and soil water in an old-growth Central Amazon rainforest. Stem water storage dominated total vegetation water storage and closely tracked seasonal soil moisture. In contrast, GNSS-T VOD exhibited opposing relationships with vegetation water compartments, being positively associated with leaf water storage (r = 0.65, p = 0.16) but negatively correlated with stem water storage and total vegetation water storage (both r = −0.83, p < 0.05). These contrasting relationships show that temporal variation in GNSS-T VOD cannot be explained by total vegetation water storage alone. Instead, these relationships highlight the importance of water partitioning among vegetation compartments when interpreting GNSS-T VOD. These observations provide a benchmark for interpreting L-band VOD in high-biomass tropical forests.

Source: Environmental Research Letters

DOI: 10.1088/1748-9326/aeb4cb

Authors: Harley Bravos Da Silva, Adriano Lima, Regison Oliveira, Bruno Gimenez, Kyeungwoo Cho, Jingfeng Wang, Andreas Colliander, Jeffrey Chambers, Xiangtao Xu, Hillary S Jenkins, Christian Frankenberg, Niro Higuchi, Robinson Negron-Juarez

Institutions: Instituto Nacional de Pesquisas da Amazônia, Georgia Institute of Technology, Finnish Meteorological Institute, Lawrence Berkeley National Laboratory, Cornell University, University of Redlands, California Institute of Technology

Language: English

Topic: Soil Moisture and Remote Sensing

Subfield: Environmental Engineering

Field: Environmental Science

Domain: Physical Sciences

SDG: Life on land

Open Access status: gold

Estimated APC paid: $3,045

Funders: National Science Foundation, U.S. Department of Energy, National Aeronautics and Space Administration, Ministério da Ciência, Tecnologia e Inovação, Conselho Nacional de Desenvolvimento Científico e Tecnológico, Fundação de Amparo à Pesquisa do Estado do Amazonas, Office of Science, Biological and Environmental Research

OpenAlex ID: W7222358321