An improved process-oriented hydro-biogeochemical model for simulating dynamic fluxes of methane and nitrous oxide in alpine ecosystems with seasonally frozen soils
<p>The hydro-biogeochemical model Catchment Nutrient Management Model – DeNitrification-DeComposition (CNMM-DNDC) was established to simultaneously quantify ecosystem productivity and losses of nitrogen and carbon at the site or catchment scale. As a process-oriented model, this model is expec...
| Main Authors: | , , , , , , , , , , , |
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| Format: | Article |
| Language: | English |
| Published: |
Copernicus Publications
2021-07-01
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| Series: | Biogeosciences |
| Online Access: | https://bg.copernicus.org/articles/18/4211/2021/bg-18-4211-2021.pdf |
| Summary: | <p>The hydro-biogeochemical model Catchment Nutrient
Management Model – DeNitrification-DeComposition (CNMM-DNDC) was established
to simultaneously quantify ecosystem productivity and losses of nitrogen and
carbon at the site or catchment scale. As a process-oriented model, this
model is expected to be universally applied to different climate zones,
soils, land uses and field management practices. This study is one of many
efforts to fulfill such an expectation, which was performed to improve the
CNMM-DNDC by incorporating a physically based soil thermal module to simulate
the soil thermal regime in the presence of freeze–thaw cycles. The modified
model was validated with simultaneous field observations in three typical
alpine ecosystems (wetlands, meadows and forests) within a catchment located
in seasonally frozen regions of the eastern Tibetan Plateau, including
observations of soil profile temperature, topsoil moisture, and fluxes of methane (CH<span class="inline-formula"><sub>4</sub></span>)
and nitrous oxide (N<span class="inline-formula"><sub>2</sub></span>O). The validation showed that the modified
CNMM-DNDC was able to simulate the observed seasonal dynamics and magnitudes
of the variables in the three typical alpine ecosystems, with index-of-agreement values of 0.91–1.00, 0.49–0.83, 0.57–0.88 and 0.26–0.47,
respectively. Consistent with the emissions determined from the field
observations, the simulated aggregate emissions of CH<span class="inline-formula"><sub>4</sub></span> and N<span class="inline-formula"><sub>2</sub></span>O
were highest for the wetland among three alpine ecosystems, which were
dominated by the CH<span class="inline-formula"><sub>4</sub></span> emissions. This study indicates the possibility
for utilizing the process-oriented model CNMM-DNDC to predict
hydro-biogeochemical processes, as well as related gas emissions, in
seasonally frozen regions. As the original CNMM-DNDC was previously
validated in some unfrozen regions, the modified CNMM-DNDC could be
potentially applied to estimate the emissions of CH<span class="inline-formula"><sub>4</sub></span> and N<span class="inline-formula"><sub>2</sub></span>O from
various ecosystems under different climate zones at the site or catchment
scale.</p> |
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| ISSN: | 1726-4170 1726-4189 |