Linking Water and Carbon Cycles Across Landscapes
Photo by Ranjithsiji (Wikimedia Commons)
New method to estimate plant productivity with high accuracy may improve environmental predictions.
The Science
Water and carbon cycles are deeply linked through plant processes, but understanding their relationship at medium to large scales has been challenging. Plants absorb carbon dioxide through photosynthesis while releasing water vapor through transpiration, forming a direct connection between gross primary productivity (GPP) and evapotranspiration (ET). Understanding how water and carbon cycles interact is essential for predicting environmental changes and informing water management, but models often struggle to capture this relationship accurately.
The Impact
This study provides a new approach by establishing a simple and transferable link between GPP and ET across different landscapes. By using widely available earth system and vegetation data, researchers developed a method to estimate plant productivity with high accuracy. The findings may enhance the estimation of water and carbon fluxes in remote sensing data and enable carbon flux modeling in hydrologic models. By refining how vegetation is represented in environmental simulations, fields such as hydrology, Earth system and environmental sciences, and ecology could benefit.
Summary
This study examined data from 380 catchments across the contiguous United States to determine how ET and GPP interact. Researchers confirmed that a strong linear relationship exists between the two, with predictable variations depending on temperature, precipitation, and vegetation. They developed a method to regionalize this relationship using environmental factors, such as temperature, radiation, and precipitation patterns, and landscape conditions, such as vegetation type and green vegetation fraction. A comparison of successful estimations of GPP and ET with data from AmeriFlux sites validated the approach. These findings demonstrate the method’s ability to improve the modeling of ecosystem functions at multiple scales. The method also enhances the accuracy of remote sensing–based GPP estimates and coupled water–carbon simulations in land surface and Earth system models. The results highlight a robust framework for integrating vegetation dynamics into hydrological models, which can help achieve better predictions of environmental responses to Earth system variability.
Publication
- Abeshu, G. W., Li, H.-Y., Shi, M., Brookshire, J., Tang, J., Xu, C., McDowell, N. & Leung, L.-Y. R. Generalized relationship linking water balance and vegetation productivity across site-to-regional scales. J. Hydrol. Eng. 29, 04024030 (2024). https://doi.org/10.1061/JHYEFF.HEENG-6163.
Funding
- This research was supported by the Energy Exascale Earth System Model (E3SM) project, funded by the Department of Energy, Office of Science, Biological and Environmental Research Earth System Model Development (ESMD) program area. Some support also came from the Integrated Coastal Modeling project, through support by the ESMD and the Regional and Global Model Analysis (RGMA) program areas, and the Environmental System Science program through the River Corridor Scientific Focus Area.
Contact
- L. Ruby Leung, Pacific Northwest National Laboratory
- Guta Abeshu, Pacific Northwest National Laboratory
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