Stock di Carbonio Attuale - Carbonio Organico del Suolo (SOC)

Land Usev0

Responsible:Niccolò Calandri

Current Carbon Stock — Soil Organic Carbon (SOC)

Overview

The Current Carbon Stock — Soil Organic Carbon (SOC) layer quantifies the carbon contained in the top 30 cm of soil derived from decomposed organic matter, expressed in tonnes of carbon per hectare (tC/ha). Soil organic carbon is the largest terrestrial carbon pool, containing approximately 1,500 Gt C globally in the top meter — more than twice the carbon in the atmosphere and three times the carbon in all living vegetation combined.

SOC accumulates through the decomposition of plant litter, root exudates, and microbial biomass. Its concentration is governed by the balance between organic matter inputs (from vegetation productivity) and losses (through microbial decomposition, erosion, and leaching). Climate, soil texture, land management, and vegetation type are the primary controls on SOC stocks.

SOC is critical for:

Climate change mitigation — soils can sequester or release vast quantities of CO2
Soil health assessment — SOC improves water retention, nutrient cycling, and soil structure
Agricultural sustainability — SOC depletion reduces crop productivity
Ecosystem service valuation — carbon payments for soil carbon sequestration

Calculation Methodology

Random Forest downscaling pipeline for SOC extraction:

Baseline extraction — The Walker et al. 2022 SOC density raster (top 30 cm) is loaded from S3 and clipped to the area of interest
Feature engineering — For each pixel:
- NDVI from Sentinel-2 — correlates with organic matter inputs to soil
- Land cover class from Dynamic World — cropland vs. forest vs. grassland have distinct SOC levels
- Elevation from SRTM DEM — affects temperature, moisture, and decomposition rates
Training — Random Forest regressor trained on baseline SOC values
Prediction — Model predicts SOC at ~200 m resolution
Validation — Cross-validation metrics (R-squared, RMSE)

Output unit: tC/ha (tonnes of carbon per hectare, top 30 cm SOC)

Data Sources

Code	Name	Provider	Type	Coverage	Resolution	Reference Year
Walker 2022	Global Carbon Density (SOC)	Walker et al. / S3	Raster (COG)	Global	~300 m	2016
`COPERNICUS/S2_SR_HARMONIZED`	Sentinel-2 L2A	ESA/Copernicus	Multispectral	Global	10 m	2017 — present
`GOOGLE/DYNAMICWORLD/V1`	Dynamic World	Google/WRI	Land cover	Global	10 m	2015 — present
`USGS/SRTMGL1_003`	SRTM DEM	NASA/USGS	Elevation	60N-56S	30 m	2000

Quality Range and Levels

Indicator	Unit	Range	Inverted
`carbon_stock_current_soc`	tC/ha	[0, 5, 15, 40, 80, 150]	No

Inverted = No: a higher value indicates greater soil carbon storage.

Level	Thresholds	Interpretation
E (Very Low)	< 5 tC/ha	Desert soils, heavily degraded or sealed surfaces
D (Low)	5-15 tC/ha	Arid croplands, eroded soils, sandy substrates
C (Moderate)	15-40 tC/ha	Temperate grasslands, managed croplands, young forests
B (High)	40-80 tC/ha	Forest soils, permanent grasslands, wetland margins
A (Very High)	> 80 tC/ha	Peatlands, organic soils, tropical forest floors, marshes

Technical Notes

SOC estimates refer to the top 30 cm of soil; deeper carbon stocks (30-100 cm) are not included
SOC has high spatial variability even within small areas due to micro-topography and land management history
Peatlands and organic soils can have extremely high SOC values (>200 tC/ha in top 30 cm)
SOC responds slowly to land use changes; decades may be needed to detect significant stock changes

References

Walker, W.S. et al. (2022). "The global potential for increased storage of carbon on land". PNAS, 119(23), e2111312119.
Spawn, S.A. et al. (2020). "Harmonized global maps of above and belowground biomass carbon density in the year 2010". Scientific Data, 7, Article 112.
Breiman, L. (2001). "Random Forests". Machine Learning, 45(1), pp. 5-32.

Data Sources & References

Sources

WRD_CARBN_22

Methodology

Il layer Carbon Stock Attuale - SOC viene calcolato estraendo la componente di carbonio organico del suolo (Soil Organic Carbon, primi 30 cm) dalla mappa globale di densita di carbonio di Walker et al. (2022). Il SOC si accumula dalla decomposizione di lettiera vegetale, essudati radicali e biomassa microbica. Il raster baseline viene raffinato tramite Random Forest utilizzando NDVI (Sentinel-2), copertura del suolo (Dynamic World) ed elevazione (SRTM) come predittori. L'elevazione e particolarmente informativa per il SOC poiche influenza temperatura, umidita e tassi di decomposizione. Il SOC e il piu grande pool di carbonio terrestre a livello globale. Output in tC/ha a ~200 m di risoluzione.