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Hybrid spatiotemporal modeling of nutrient cycling in wetland ecosystems using advanced mapping techniques and machine learning approaches


Abstract

Accurate spatiotemporal monitoring of nutrient cycling in wetlands is critical for conservation. However, traditional field-based methods are often inadequate for capturing the overall dynamics of wetlands. To address this challenge, we developed and validated a two-stage hybrid Random Forest regression framework that seamlessly integrated in-situ water quality data with wetland features and satellite imagery from Sentinel-1 and Sentinel-2 within the Google Earth Engine platform. The framework first models baseline nutrient concentrations using discrete wetland characteristics (stage 1) and then models the resulting spatial residual using continuous satellite-derived predictors (stage 2). We applied the model to predict quarterly nitrogen and phosphorus concentrations over four years (2021–2024) in the Beavercreek Wetlands Greenway (BWG), a mixed-use landscape. The two-stage model demonstrated exceptional predictive performance for both nitrogen (final (text {r}^{2}) = 0.90, RMSE = 0.129 mg/L) and phosphorus (final (text {r}^{2}) = 0.89, RMSE = 0.007 mg/L). The variable importance analysis revealed divergent predictive pathways: nitrogen concentration was driven by both landscape-level factors (e.g., land use classes, area and perimeter of wetlands, rainfall) and in-stream biophysical conditions captured by remote sensing (e.g., vegetation and SAR indices), whereas phosphorus was controlled by source-loading from developed land uses. We produced spatiotemporal maps to visualize these distinct patterns. The maps revealed that the BWG system is subject to seasonal nitrogen stress but has experienced significant recovery from prior phosphorus impairment. This study offers a diagnostic framework that could inform focused wetland management strategies and aid in monitoring the health and function of wetland ecosystems.

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Data availibility

The datasets generated during and/or analyzed during the current study are available from the corresponding author upon reasonable request.

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Funding

This research was supported by the Evans-Allen funds of the U.S. Department of Agriculture, National Institute of Food and Agriculture [NI241445XXXXG004].

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E.A.L.S. conceptualized the study. E.A.L.S. and K.S. conducted the experiments. E.A.L.S. and S.S.K. provided inputs for methodology, software, and resources. S.S.K. project administration. E.A.L.S., K.S., and R.B. conducted the field survey and experiments. E.A.L.S. and K.S. analyzed the results. R.B. and K.S. conducted the laboratory experiments. All authors read and approved the final manuscript.

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Eric Ariel L. Salas.

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Salas, E.A.L., Schrack, K., Kumaran, S.S. et al. Hybrid spatiotemporal modeling of nutrient cycling in wetland ecosystems using advanced mapping techniques and machine learning approaches.
Sci Rep (2026). https://doi.org/10.1038/s41598-026-40585-5

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