Editing Soil organic carbon stock

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|+ SIGNAL Earth Structured Data
|-
! Object type
| Damage Signal
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! SIGNAL Earth ID
| DS-00149
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! Observable type
| Soil organic carbon stock
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! Unit
| tC (metric tons of carbon stored in soil)
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! Temporal structure
| Periodic
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! Monitoring backbone
| —
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{{SignalTerm|type=DS|id=DS-00149|label=Soil organic carbon stock}} represents the amount of carbon stored within the organic fraction of soil across various ecosystems globally. It is a critical component of the terrestrial carbon cycle, influencing soil fertility, ecosystem productivity, and carbon sequestration potential. Understanding soil organic carbon stocks helps inform assessments of land health and the broader carbon balance in the context of climate change.

This phenomenon encompasses the carbon contained in decomposed plant and animal materials within the soil matrix, typically measured in metric tons of carbon per unit area. Soil organic carbon stock varies spatially and temporally due to factors such as vegetation type, land use, climate, and soil management practices.

As a state indicator within the land domain, soil organic carbon stock reflects changes in soil quality and ecosystem function. It is relevant for evaluating environmental conditions related to land degradation, agricultural sustainability, and greenhouse gas fluxes.

== Geographic / System Context ==
Soil organic carbon stock is a globally distributed environmental attribute, present in soils across diverse biomes including forests, grasslands, wetlands, agricultural lands, and deserts. Its distribution is influenced by geographic factors such as climate zones, soil types, topography, and vegetation cover. For example, boreal and temperate forests often exhibit higher soil organic carbon stocks compared to arid regions. Depth profiles of soil organic carbon, commonly assessed down to 100 cm, provide insight into carbon storage within different soil horizons and landscape positions.

== Monitoring and Measurement ==
Monitoring soil organic carbon stock involves field sampling combined with laboratory analysis to quantify carbon content in soil samples. Standardized protocols include soil core extraction at specified depths, followed by chemical or spectroscopic methods to determine organic carbon concentration. Remote sensing and modeling approaches complement ground measurements by estimating spatial patterns and temporal changes over large areas. Institutions such as the Food and Agriculture Organization ([https://en.wikipedia.org/wiki/Food_and_Agriculture_Organization FAO]) and research networks contribute data and methodologies for consistent monitoring. Advances in global meta-analyses synthesize data from multiple ecosystems to characterize soil organic carbon distribution patterns.

Within the SIGNAL system, this phenomenon is treated as a defined environmental signal whose boundaries and measurement conventions are described below.

== Signal Definition ==
The soil organic carbon stock signal quantifies the mass of organic carbon contained within the soil organic matter of a defined geographic unit, expressed in metric tons of carbon (tC). It captures the state condition of soil carbon pools within the land domain, reflecting accumulated organic carbon in soil layers typically sampled from the surface down to depths of 20 to 100 centimeters. This signal serves as an indicator of soil carbon storage capacity and ecosystem carbon dynamics.

== Boundary Conditions ==
Boundary inclusions encompass all organic carbon contained within soil organic matter fractions in mineral and organic soils, including carbon derived from plant residues, microbial biomass, and humified organic compounds. The signal includes carbon stored across soil horizons within the defined depth range relevant to ecosystem carbon assessments. Boundary exclusions omit inorganic carbon forms such as carbonates, aboveground biomass carbon, and carbon in aquatic sediments or peatlands unless explicitly classified as soil. The signal does not include transient carbon fluxes such as dissolved organic carbon in soil water or atmospheric carbon pools.

== Aggregation Semantics ==
Geographic aggregation of soil organic carbon stock data is performed by summing or averaging carbon stocks over defined spatial units such as grid cells, land cover types, or administrative regions to facilitate regional and global assessments. Temporal aggregation follows a periodic structure, with measurements or estimates updated at intervals appropriate to capture meaningful changes, often annually or multi-annually. Cross-signal aggregation allows integration with related environmental signals, enabling combined analyses of land degradation, productivity, and moisture status. Aggregations account for heterogeneity in soil properties and land use to maintain representativeness and comparability across scales.

== Observational Status ==
Current monitoring of soil organic carbon stock relies on a combination of field measurements, laboratory analyses, and remote sensing data integrated through modeling frameworks. Data availability varies regionally, with some ecosystems and countries maintaining comprehensive datasets while others have limited coverage. Ongoing research efforts aim to improve spatial resolution, temporal frequency, and methodological consistency. Future SIGNAL releases may incorporate enhanced datasets, refined boundary definitions, and improved aggregation methods to support more detailed and accurate assessments of soil carbon dynamics.

== Related Signals ==
* Desertification severity index
* Land conversion rate to cropland
* Net primary productivity (NPP)
* Soil degradation severity index
* Soil moisture content
* Wetland area extent

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== Key Associated People ==
* '''H. Wang''' [Lead author]
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== Sources ==
* [https://essd.copernicus.org/articles/17/3375/2025/ Global patterns of soil organic carbon distribution in the 20–100 cm soil profile for different ecosystems: a global meta-analysis — 2025]
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