Accurate forest-carbon estimates are essential for climate mitigation, restoration planning and monitoring, reporting and verification, yet conventional field inventories are expensive and spatially discontinuous. This study evaluated whether freely available Sentinel-2 imagery combined with statistical and machine-learning models can estimate and map forest carbon across the Mau Forest Complex, Kenya. Existing geo-referenced forest inventory data comprising 3,907 measured trees were linked to seven Sentinel-2 vegetation indices: Normalized Difference Vegetation Index (NDVI), Enhanced Vegetation Index (EVI), Soil-Adjusted Vegetation Index (SAVI), Normalized Difference Moisture Index (NDMI), Normalized Burn Ratio (NBR), red-edge Chlorophyll Index (CIre) and Red-Edge Normalized Difference Vegetation Index (RENDVI). Above-ground biomass was estimated using a pan-tropical allometric equation; below-ground biomass, carbon stock and CO2 equivalent were subsequently derived using IPCC factors. Ordinary linear regression, a linear mixed-effects model, Random Forest and Extreme Gradient Boosting (XGBoost) were compared using a 70:30 training-test split, with five-fold cross-validation for machine-learning hyperparameter tuning. All vegetation indices were positively associated with above-ground biomass (p<0.001), with CIre (Pearson r=0.530), RENDVI (r=0.516) and NDMI (r=0.513) among the strongest correlates. On the independent test set, XGBoost performed best (R2=0.473, RMSE=0.424, MAE=0.327), followed by Random Forest (R2=0.468, RMSE=0.426, MAE=0.329), the mixed-effects model (R2=0.454, RMSE=0.431, MAE=0.333) and linear regression (R2=0.436, RMSE=0.438, MAE=0.340). XGBoost reduced RMSE by 3.3% relative to the linear baseline. Residual spatial autocorrelation was negligible (Moran’s I=0.059). Spatial prediction identified higher carbon densities in western and south-western portions of the Complex and lower values in more disturbed eastern blocks. The study contributes a reproducible, low-cost benchmark of linear, mixed-effects and ensemble models for spatial forest-carbon monitoring in a heterogeneous African montane forest; the modest gain from nonlinear models shows that optical indices alone limit accuracy, so future improvements will likely require structural information from radar or LiDAR.
| Published in | Applied and Computational Mathematics (Volume 15, Issue 5) |
| DOI | 10.11648/j.acm.20261505.16 |
| Page(s) | 206-219 |
| Creative Commons |
This is an Open Access article, distributed under the terms of the Creative Commons Attribution 4.0 International License (http://creativecommons.org/licenses/by/4.0/), which permits unrestricted use, distribution and reproduction in any medium or format, provided the original work is properly cited. |
| Copyright |
Copyright © The Author(s), 2026. Published by Science Publishing Group |
Mau Forest Complex, Above-ground Biomass, Carbon Sequestration, Sentinel-2, Random Forest, XGBoost, Remote Sensing, REDD+
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APA Style
Onyango, F. J., Wamwea, C., Langat, A. K. (2026). Estimating and Mapping Forest Carbon Sequestration in the Mau Forest Complex Using Sentinel-2 Remote Sensing and Machine Learning. Applied and Computational Mathematics, 15(5), 206-219. https://doi.org/10.11648/j.acm.20261505.16
ACS Style
Onyango, F. J.; Wamwea, C.; Langat, A. K. Estimating and Mapping Forest Carbon Sequestration in the Mau Forest Complex Using Sentinel-2 Remote Sensing and Machine Learning. Appl. Comput. Math. 2026, 15(5), 206-219. doi: 10.11648/j.acm.20261505.16
@article{10.11648/j.acm.20261505.16,
author = {Fred Junior Onyango and Charity Wamwea and Amos Kipkorir Langat},
title = {Estimating and Mapping Forest Carbon Sequestration in the Mau Forest Complex Using Sentinel-2 Remote Sensing and Machine Learning},
journal = {Applied and Computational Mathematics},
volume = {15},
number = {5},
pages = {206-219},
doi = {10.11648/j.acm.20261505.16},
url = {https://doi.org/10.11648/j.acm.20261505.16},
eprint = {https://article.sciencepublishinggroup.com/pdf/10.11648.j.acm.20261505.16},
abstract = {Accurate forest-carbon estimates are essential for climate mitigation, restoration planning and monitoring, reporting and verification, yet conventional field inventories are expensive and spatially discontinuous. This study evaluated whether freely available Sentinel-2 imagery combined with statistical and machine-learning models can estimate and map forest carbon across the Mau Forest Complex, Kenya. Existing geo-referenced forest inventory data comprising 3,907 measured trees were linked to seven Sentinel-2 vegetation indices: Normalized Difference Vegetation Index (NDVI), Enhanced Vegetation Index (EVI), Soil-Adjusted Vegetation Index (SAVI), Normalized Difference Moisture Index (NDMI), Normalized Burn Ratio (NBR), red-edge Chlorophyll Index (CIre) and Red-Edge Normalized Difference Vegetation Index (RENDVI). Above-ground biomass was estimated using a pan-tropical allometric equation; below-ground biomass, carbon stock and CO2 equivalent were subsequently derived using IPCC factors. Ordinary linear regression, a linear mixed-effects model, Random Forest and Extreme Gradient Boosting (XGBoost) were compared using a 70:30 training-test split, with five-fold cross-validation for machine-learning hyperparameter tuning. All vegetation indices were positively associated with above-ground biomass (p2=0.473, RMSE=0.424, MAE=0.327), followed by Random Forest (R2=0.468, RMSE=0.426, MAE=0.329), the mixed-effects model (R2=0.454, RMSE=0.431, MAE=0.333) and linear regression (R2=0.436, RMSE=0.438, MAE=0.340). XGBoost reduced RMSE by 3.3% relative to the linear baseline. Residual spatial autocorrelation was negligible (Moran’s I=0.059). Spatial prediction identified higher carbon densities in western and south-western portions of the Complex and lower values in more disturbed eastern blocks. The study contributes a reproducible, low-cost benchmark of linear, mixed-effects and ensemble models for spatial forest-carbon monitoring in a heterogeneous African montane forest; the modest gain from nonlinear models shows that optical indices alone limit accuracy, so future improvements will likely require structural information from radar or LiDAR.},
year = {2026}
}
TY - JOUR T1 - Estimating and Mapping Forest Carbon Sequestration in the Mau Forest Complex Using Sentinel-2 Remote Sensing and Machine Learning AU - Fred Junior Onyango AU - Charity Wamwea AU - Amos Kipkorir Langat Y1 - 2026/10/23 PY - 2026 N1 - https://doi.org/10.11648/j.acm.20261505.16 DO - 10.11648/j.acm.20261505.16 T2 - Applied and Computational Mathematics JF - Applied and Computational Mathematics JO - Applied and Computational Mathematics SP - 206 EP - 219 PB - Science Publishing Group SN - 2328-5613 UR - https://doi.org/10.11648/j.acm.20261505.16 AB - Accurate forest-carbon estimates are essential for climate mitigation, restoration planning and monitoring, reporting and verification, yet conventional field inventories are expensive and spatially discontinuous. This study evaluated whether freely available Sentinel-2 imagery combined with statistical and machine-learning models can estimate and map forest carbon across the Mau Forest Complex, Kenya. Existing geo-referenced forest inventory data comprising 3,907 measured trees were linked to seven Sentinel-2 vegetation indices: Normalized Difference Vegetation Index (NDVI), Enhanced Vegetation Index (EVI), Soil-Adjusted Vegetation Index (SAVI), Normalized Difference Moisture Index (NDMI), Normalized Burn Ratio (NBR), red-edge Chlorophyll Index (CIre) and Red-Edge Normalized Difference Vegetation Index (RENDVI). Above-ground biomass was estimated using a pan-tropical allometric equation; below-ground biomass, carbon stock and CO2 equivalent were subsequently derived using IPCC factors. Ordinary linear regression, a linear mixed-effects model, Random Forest and Extreme Gradient Boosting (XGBoost) were compared using a 70:30 training-test split, with five-fold cross-validation for machine-learning hyperparameter tuning. All vegetation indices were positively associated with above-ground biomass (p2=0.473, RMSE=0.424, MAE=0.327), followed by Random Forest (R2=0.468, RMSE=0.426, MAE=0.329), the mixed-effects model (R2=0.454, RMSE=0.431, MAE=0.333) and linear regression (R2=0.436, RMSE=0.438, MAE=0.340). XGBoost reduced RMSE by 3.3% relative to the linear baseline. Residual spatial autocorrelation was negligible (Moran’s I=0.059). Spatial prediction identified higher carbon densities in western and south-western portions of the Complex and lower values in more disturbed eastern blocks. The study contributes a reproducible, low-cost benchmark of linear, mixed-effects and ensemble models for spatial forest-carbon monitoring in a heterogeneous African montane forest; the modest gain from nonlinear models shows that optical indices alone limit accuracy, so future improvements will likely require structural information from radar or LiDAR. VL - 15 IS - 5 ER -