RL4. Assessing ecosystem services provided by soils at different spatial scales

Nowadays, soils are no longer considered as simple production supports but as systems providing different services (supporting, regulating, provisioning and cultural services from MAE report, 2005). In that frame, the objectives of our research are first to identify the major determinants of the supply level of the different ecosystem services provided by soils, and second to develop the needed indicators that we have to define, build or adapt for each context. Finally, we use ecosystem services as multi-criteria assessment tools in order to inform various stakeholders (policy makers, landowners, farmers) with the gains and losses of soil services resulting from changes in land-use, production system or agricultural practices. All this research is based on and renew the "historical" competences of the Soil team (biogeochemical cycles, fate of contaminants, modeling, and soil mapping) and also of the ECOSYS.

As a first example of final end-product and directly related with the first topic on organic waste recycling, Fiona Obriot developed in her thesis a multi-criteria tool, based on 7 indices of soil and crop qualities (soil fertility, soil biodiversity, soil biological activities, soil physical properties, soil contamination (“available” and “total”) and crop productivity) used as indicators of soil services (Fig. 15) to assess how exogenous factors or anthropogenic pressures, here a change from mineral to organic fertilisation by recycling organic waste products modifies the delivery of bundles of soil services. Regular application of organic waste products improves soil biodiversity, delivery of nutrients to crops, climate change mitigation and water regulation relative to mineral fertilization while maintaining or even increasing crop yield and quality with intensity generally depending on their characteristics. Organic amendments negatively affected the soil contamination index when considering total concentrations but increase the service of filtration / sequestration / storage / accumulation of toxics by soils as shown by decreased available fractions.

Similarly, Baptist Grard in his PhD (2017) on the development of urban agriculture on green roofs, showed that the technosols, made of organic and mineral wastes, provided several ecosystem services (e.g. food production, runoff mitigation, organic wastes recycling) and were of considerable importance for the regulation of the amount of rainwater going back to urban networks (the technosoils made of compost and crushed wood, retained 74 to 84% of the incoming rainfall water, Grard et al., 2018).

Finally, in the context of the ASSETS project (2015-2019, LabEx BASC) concerning ecosystem services provided by soils during the increasing urbanisation of the Saclay plateau, we showed that the intensity of the water supply service to plants, quantified through the available water capacity (AWC), varied with the intensity but also the location of soil sealing. With a loss of service ranging from 19% to 35%, taking soil quality into account can limit the loss of ecosystem services associated with their waterproofing (Fig. 16).

Our research has linked with the meta-program of INRAE EcoServ which funded the international workshop organized by Philippe Baveye (Workshop on Soil Ecosystem Services, St Rémy-les-Chevreuse, December 15-16, 2015) and on the French Evaluation of Ecosystems and Ecosystem Services (EFESE) from which the methods were used in the project ASSETS. They were developed in collaboration with various laboratories in the Paris region such as HBAN, LSCE, ESE, SADAPT, Terres Inovia, Agronomy units, but also other French laboratories such as Genial, LSE, AgroImpact, Agrotransfert.

The actors of the territory are also involved in our projects via organizations such as EPAPS and Terre et Cité for projects concerning the Plateau de Saclay, or companies like Culture en Ville, Elisol, Topager, Bio Yvelines Service, La boîte à champignons for the urban microfarm project.

We also contributed to international assessments of ecosystem services by contributing as lead author to the first assessment of biodiversity and ecosystem services of Europe and Central Asia led by the International Panel of Biodiversity and Ecosystem Services (IPBES, 2018).

Scientific stategy and project

One of the key-point towards the use of the soil services framework in decision-making is to be able to quantify the delivery of soil services with both sufficient accuracy and convenience. We thus built a field experiment dedicated to the quantification of the actual delivery of some soil services, namely food and ground water production, global climate regulation by carbon sequestration and mediation of wastes and toxic substances of anthropogenic origin. Such quantifications will then be compared to alternative quantifications and assessments either through mechanistic, functional, statistical modeling or through expert judgement from the plot to the small agricultural area levels to find which way provides the best balance between accuracy and efficiency. Different methods of service evaluation like direct measurements, simulations with a soil-plant model and expert approaches will be compared (ASSETS Project of Saclay Plateau, post doc of Maha Chalhoub and PhD Pauline Choquet).

The use of the soil services framework as a multi-criteria assessment tool will also be extended to innovative production systems as urban microfarms within the SEMOIRS project. The goals are i) to identify the services they could provide to the city (biodiversity support, supply of food, water cycle regulation, climate and organic waste regulation as well as cultural services, i.e. landscape improvement) and ii) to help project leaders, urban planners and local authorities to design and manage this form of urban agriculture by maximizing the delivery of ecosystem services.

Finally, an integrated modeling will be implemented in the PROTERR project using the MAELIA platform to take into account both ecosystem services delivery and decision-making in the context of organic waste recycling (RL1). Different models will be used in the MAELIA platform to simulate cropping systems functioning and wastes production and fluxes. A wide range of indicators will be computed to perform a multicriteria assessment at different scales (from field to a small agricultural area), the spatial layers of which are likely to originate from the above-presented spatial approaches (RL3). The effect of decision making will be explicitly modelled (agent-based modeling) to test the effect of various regulations. This project will be carried out in collaboration with several laboratories studying organic wastes recycling and with a laboratory involved in multicriteria assessment of agricultural systems (LAE).