Project Details
Projekt
Interrelation of biochemical and physicochemical forest floor properties: Effect of SOM-mineral association and interaction
Applicant
Professor Dr. Jörg Prietzel
Subject Area
Soil Sciences
Forestry
Forestry
Term
since 2022
Project identifier
Deutsche Forschungsgemeinschaft (DFG) - Project number 457330647
In contrast to widespread perceptions, forest floor (FF) O layers in addition to soil organic matter (SOM) often contain considerable contents of inorganic (mineral) components. Important physicochemical FF properties like amount and types of minerals, spatial arrangement of SOM and minerals, as well as extent and type of SOM-mineral association in O layers are probably controlled by site factors (nutrient supply, climate), and mediated by soil microorganisms, soil fauna, and plant roots. On the other hand, physicochemical FF properties likely affect biochemical properties (e.g. functional C groups, SOM decomposition status, nutrient content). They thus influence FF’s provision of important ecosystem services (e.g. C sequestration, water and nutrient storage) and their vulnerability by climate warming. In project P3, these issues are investigated by combining an observational approach with an experimental approach. Joint key element of both approaches is the application of a novel density fractionation method, which enables distinguishing and quantifying non-mineral-associated and mineral-associated SOM in FF samples. In the observational approach, the effects of the site factors climate and P nutritional status as well as their interaction on the extent and types of SOM-mineral associations in the FF and on key biochemical FF SOM properties are quantified by investigating the 12 FOR 5315 study sites, which constitute a full-factored matrix with different combinations of climate, and P nutrition status. Cooperation with other FOR 5315 projects (P2, P6, P7) allows for identifying and quantifying effects of tree roots, different soil fauna and microorganism communities, as well as site-specific C and N turnover patterns. The experimental approach is based on an intensive cooperation with projects P2 and P6. Here, different FF mesocosms, either allowing or preventing activity of roots, macrofauna, or mesofauna, respectively, will be investigated 0.5 and 1 years after mesocosm installation at all study sites. Using the methods described above, the respective effects of root, macrofauna, and mesofauna activity on the formation of SOM mineral association and related changes in biochemical SOM properties, as well as the turnover of isotopically labelled (13C, 15N) litter after surficial application in different FF horizons and SOM fractions are assessed. Ultimately, P3 will develop a comprehensive concept of SOM-mineral association in FFs as dependent on site properties and site-specific FF mineral input and transformation processes (bioturbation, root activity, SOM mineralization).
DFG Programme
Research Units
