Learn more about the Forest-DNDC-Tropica project

About Forest-DNDC-Tropica

PnET-N-DNDC was modified by Kiese et al. (2005) to produce reliable estimates of N2O emissions from tropical rainforest ecosystems, a significant source of global N2O.  Differences in forest growth and soil hydrological properties between temperate and tropical regions meant the model required adaption prior to application in tropical regions, although the general structure of the original model was maintained. 

New parameterisations associated with plant physiology and soil hydrology were added to PnET-DNDC as well as algorithms relating to biological fixation of N, representing the effects of heavy rainfall damage and of water stress on daily leaf litterfall.  Soil moisture conditions drive a dentrifier activity index which influences N turnover by denitrification.  A biological N fixation algorithm was also added. Tree growth functions were also modified in Forest-DNDC-Tropica to enable growth to occur throughout the year as it is not limited by temperature (Kiese et al., 2005).

Daily N2O emissions simulated by Kiese et al. (2005) were in agreement with field observations in the wet tropics of Australia and Costa Rica and the model reproduced dynamic N2O patterns during the wet season.  The model was shown to be sensitive to soil properties (pH, clay content, soil organic carbon) and climatic factors (rainfall and temperature).  The tool may be used to scale up N2O emissions from site to regional scale, in order to improve regional or global N2O inventories. Kiese et al. (2005) recognise that further validation against detailed observed data would be desirable and that Forest-DNDC-Tropica should be networked with hydrological models in the future.

Some further development of the Forest-DNDC-Tropica model developed by Kiese et al. (2005) was then made by Werner (2007).  Werner et al. (2007) provides further details of the three sub-models which comprise Forest-DNDC-Tropica and which simulate soil climate, soil decomposition and forest growth.  The distribution of soil organic carbon for the Australian rainforest soils was revised.  Pedo-transfer functions which are specific to tropical soils and vital for simulating soil hydrology were added. Parameters that relate to wood mass, leaf mass and floor mass were updated with externally supplied values specifically calibrated for tropical rainforests (Werner et al., 2006).  The model was also revised by Werner (2007) to comply with ANSI C++. 

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