Cross Cutting Questions

Based on close cooperation between the partners the RU will explain the impact of temperature and P supply on FF properties and corresponding service fulfilment as mediated by FF biota. Central to our research are the 12 study sites of the RU representing the factors T and P supply. We will use different research methods which rely either on sample components taken at the study sites or are performed on-site. Thus, the joint study sites provide strong links between the projects and the cooperation is directed and structured by addressing controls, properties and services of FFs . In order to further optimise and specify the synergies from the cooperation in the RU, we have developed cross cutting (CC) questions related to the FF services of (1) nutrient provision, (2) carbon sequestration, and (3) water supply and to the identification of properties, indicating service fulfilment:

• Nutrients: Which organisms/species benefit from an increased residence time of nutrients in FF? (all projects)
• Nutrient/Carbons: Does C-nutrient coupling increase with FF turnover? (P2-P10)
• Carbon: How is the C sequestration by forest topsoil related to FF turnover? (P2, P3, P7, P11)
• Water: How is the contribution of FF to plant water supply by forest topsoil and heat balance of forest topsoil related to FF turnover? (P1, P5, P10, P11)
• Indicators: Which properties of the FF and the mineral soil and which climatic site properties are required to assess FF service fulfilment? Can FF morphological features act as integrating indicators for this set of determinants? (all projects)