Understanding the biogeochemical functioning of natural ponds in the agricultural landscape

Session: 31. - Evaluation of the Current State of Ecological Modeling and Future Perspectives

Gabriela Onandia Bieco, Leibniz Centre for Agricultural Landscape Research (ZALF), [email protected]
Gunnar Lischeid, Leibniz Centre for Agricultural Landscape Research (ZALF), [email protected]
Thomas Kalettka, Leibniz Centre for Agricultural Landscape Research (ZALF), [email protected]
George Arhonditsis, University of Toronto Scarborough, [email protected]

Abstract

Kettle holes, small shallow ponds of glacial origin, are prevalent elements of the agricultural landscape of North-East Germany. They have been acknowledged as hotspots for C turnover and nutrient cycling and therefore have the potential to significantly modulate regional element cycles. However, knowledge on the biogeochemical processes driving nutrient and primary producer seasonal dynamics in these ecosystems remains limited. We present a process-based biogeochemical model that aims to reproduce the seasonal dynamics of the carbon, nitrogen, phosphorus and oxygen cycles, as well as phytoplankton and free-floating macrophytes. After model calibration, we evaluated the ability of the model to reproduce the data collected in an exemplary kettle hole. Next, we performed a sensitivity analysis and quantified the predicted mass fluxes associated with the biogeochemical processes considered in the modeling exercise. The model reasonably reproduced the seasonal variation of nutrients, phytoplankton and free-floating macrophytes. The results indicated that internal nutrient cycling in kettle holes are mainly controlled by sediment nutrient release and decomposition of decaying submerged macrophytes. Moreover, our results suggest that the exemplary kettle hole and kettle holes structurally similar, release carbon dioxide to the atmosphere at the annual scale. Finally, we pinpoint knowledge gaps in relation to kettle hole biogeochemistry.

1. Keyword
wetlands

2. Keyword
carbon cycle

3. Keyword
lake model

4. Additional Keyword
internal nutrient cycling

5. Additional Keyword
phytoplankton

6. Additional Keyword
macrophytes