Seminar: Katrin Fleischer
- Date: Jun 9, 2022
- Time: 02:00 PM - 03:00 PM (Local Time Germany)
- Speaker: Katrin Fleischer
- Department Biogeochemical Signals (Zaehle)
- Location: Max-Planck-Institut für Biogeochemie
- Room: Hörsaal (C0.001)
Nutrient cycles are tightly linked to carbon cycles in tropical forests, controlling long-term vegetation turnover rates and short-term responses to environmental change such as elevated CO2 concentrations. In tropical wet forests of the Amazon, plants tend to grow slower in low fertility soils, while their relative investments in nutrient acquisition is likely higher due to costly mechanisms of nutrient mobilization. The decomposition of organic matter by free-living microorganisms may be the dominant pathway of nutrient mineralization for plants in low fertility soils, while inorganic pathways of nutrient release, e.g. phosphorus desorption and weathering, play a lesser role. The availability of soil nutrients to meet the plants’ higher demand under eCO2 is a key constraint on tropical forest growth under future climate change, while nutrient availability itself depends on the soil fertility status and the soil microbial community, which may act as a source or sink of nutrients under eCO2 from the plants’ perspective.
We employ the process-based terrestrial biosphere model QUINCY , coupled to the microbial-explicit soil model JSM to model shifts in coupled nutrient and carbon cycling rates at field sites with differing soil fertility in the Amazon, and to confront the modelled ecosystems with elevated CO2. We compiled a unique dataset of forest growth, soil and litter chemistry, as well as microbial growth and stoichiometry from a set of Amazon forest plots covering a large gradient in soil fertility, for model calibration and evaluation. We test the hypothesis that the contribution of microbial-driven nutrient mineralization to the nutrient supply of plants increases with lowering soil fertility, and explore the soil microbial-induced nutrient feedback to eCO2-induced carbon sequestration in tropical wet forests.
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