Regional application of PnET‐N‐DNDC for estimating the N₂O source strength of tropical rainforests in the Wet Tropics of Australia

Abstract

In contrast to the significant importance of tropical rainforest ecosystems as one of the major sources within the global atmospheric N 2 O budget (2.2-3.7 Tg N yr À1 ), regional estimates of their N 2 O source strength are still limited and highly uncertain. To contribute toward more reliable estimates of the N 2 O source strength of tropical rainforest ecosystems on a regional scale, we modified a process-oriented biogeochemical model, PnET-N-DNDC, and parameterized it to simulate C and N turnover and associated N 2 O emissions in and from tropical rainforest ecosystems. Model modifications included: (1) new parameterizations associated with plant physiology and soil hydrology and the addition of algorithms relating daily leaf litterfall to water stress as well as to daily rainfall to account for the effects of heavy rainfall damage; (2) the development of a denitrifier activity index that depends on soil moisture conditions and influences N turnover by denitrification; and (3) the addition of a biological N fixation algorithm. Daily simulated N 2 O emissions based on site data were in good agreement (model efficiencies up to 0.83) with field observations in the Wet Tropics of Australia and Costa Rica. The model was even able to reproduce the highly dynamic pattern of N 2 O emissions with short-term increases during the wet season. Sensitivity analyses demonstrated that the PnET-N-DNDC model was sensitive to changes in soil properties such as pH, clay content, soil organic carbon and climatic factors such as rainfall and temperature. By linking the PnET-N-DNDC model to a geographic information systems database, tropical rainforests in a 9000 km 2 area of the Wet Tropics of Australia are estimated to emit 962 t N 2 O-N yr À1 (2.4 kg N 2 O-N ha À1 yr À1 ) between July 1997 and June 1998. NomenclaturePTF 5 pedo-transfer function wfps 5 water filled pore space SOC 5 soil organic carbon

Modeling dissolved organic carbon in temperate forest soils: TRIPLEX-DOC model development and validation

“…Forest-DNDC has previously been used to successfully predict trace gas emissions in regional studies (Kesik et al, 2005;Kiese et al, 2005) and effects of forest management practices on soil environmental factors (Sun et al, 2006;Dai et al, 2012). Additionally, the model is currently parameterized for 12 forest ecosystem tree species/genera: pine, spruce, hemlock, fir, hardwoods, oak, birch, beech, slash pine, larch, cypress, and evergreen oak (Li et al, 2000).…”

Modeling carbon dynamics in two adjacent spruce forests with different soil conditions in Russia

“…The correlations between the measured and modeled monthly mean NEE fluxes were expressed with the R-squared values as 0.91, 0.73, 0.73 and 0.57 for Tharandt, Griffin-Aberfeldy, upland Grainesville and wetland Grainesville, respectively. Except the above-described four cases tested in this study, more validation tests have been conducted for Forest-DNDC by a number of researchers worldwide (e.g., Miehle et al, 2006;Sun et al, 2006;Kesik et al, 2005;Kiese et al, 2004;Butterbach-Bahl et al, 2004;Zhang et al, 2002;Stange et al, 2000). The validation results suggested that Forest-DNDC was applicable for C balance studies across a wide range of forest ecosystems.…”

“…Driven by climate, forest type, soil properties, management practices and other relevant input parameters, the models can simulate forest production as well as C and N cycles in the ecosystems. Among the modeling efforts, the Forest-DNDC model developed by Li and his colleagues has been widely tested for greenhouse gas studies Kiese et al, 2004;Cui et al, 2005;Kesik et al, 2005;Miehle et al, 2006). In this study, we applied Forest-DNDC for understanding the NEE fluxes observed at two adjacent forest ecosystems located at the southern boundary of European taiga in Russia.…”

Effect of temporal resolution on N2O emission inventories in Dutch fen meadows

“…[10] The model DNDC was selected because it has been calibrated and validated for many sites around the world [Brown et al, 2002;Butterbach-Bahl et al, 2001;Cai et al, 2003;Grant et al, 2004;Jagadeesh Babu et al, 2006;Kesik et al, 2005;Kiese et al, 2005;Pathak et al, 2005;Saggar et al, 2004;Xu-Ri et al, 2003;Zhang et al, 2006] and can simulate drained organic soils. Version 9.1 of DNDC was used.…”