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Soils are the largest pool of terrestrial organic carbon. They can behave as a sink or a source of atmospheric CO2 (Jacobson et al., 2000). The prediction of climate change consequences on ecosystems depends partly on the better understanding of the distribution and control of soil organic carbon (SOC) content. Artificialized areas represent nearly 3% of the World territory (9.3% in France), and by 2050 the proportion of the urban population is expected to reach 66% worldwide (Liu et al., 2014; Service de la Statistique et de la Prospective, 2015; United Nations et al., 2014). However, available data to assess whether urbanization leads to an increase or decrease of SOC and which factors explain the most the SOC distribution in these very heterogeneous soils, are extremely scarce. Hence, the effective role of urban soils in carbon sequestration and greenhouse gas balance is unknown and generally underestimated. Our hypothesis is that the anthropic factors (ie land use types and management) and vegetation cover mostly explain SOC cartography in urban soils, at a territory scale.

The first objective is to link the urban soil use, management and vegetation cover to their soil organic carbon stock (SSOC), at French territory scale. The second objective is to determine whether these factors explain the most SSOC distribution in urban soils, compared to extrinsic natural factors and soil property variables (eg., climate, nitrogen content, carbonate content, clay content), at French territory scale.