N2O and NO emission from the Nyungwe tropical highland rainforest in Rwanda

Research output: Contribution to journalArticle

Abstract

Tropical forest soils are a significant source for N2O and NO. Current estimates of N2O and NO emissions areuncertain due to the limited number of fieldmeasurements and model input data. Furthermore, considerable spatialand temporal variability exists due to variation of soil properties, vegetation characteristics and meteorology.Weused a process-based model (ForestDNDC-tropica) to estimate N2O and NO emissions from the entire (970 km2)tropical highland forest (Nyungwe) in southwestern Rwanda. Scaling these results to that regional level using legacysoil, meteorological and simulated vegetation data we found in most cases agreement between N2O and NOmeasurements and model predictions. Limited agreement was found for acid soils with high clay content and reducedmetals, indicating that abiotic N2O and NO forming processes in acidic soils might be under-represented inthe current ForestDNDC-tropica model. The Nyungwe forest was estimated to emit 439 t N2O-N year?1 (2.8–5.5 kg N2O-N ha?1 year?1) and 244 t NO-N year?1 (0.8–5.1 kg N ha?1 year?1), corroborating previous studies intropical forests and highlighting that also tropical highland rainforest soils are a major source of atmospheric N2Oand NO. The uncertainty for the N2O and NO emission estimates was 153 and 50 t N2O-N year?1 and 36 and 16 tNO-N year?1 considering uncertainty in model input data and annual variability, respectively. The results showedthat soil bulk density and pH were the most influential factors driving spatial variation and model uncertainty. Toimprove global model-based estimates of N2O and NO emission from tropical forest focus should therefore alsobe oriented in delivering more detailed soil and vegetation data.

Details

Authors
  • N. Gharahi Ghehi
  • C. Werner
  • K. Hufkens
  • R. Kiese
  • E. Van Ranst
  • D. Nsabimana
  • Göran Wallin
  • Leif Klemedtsson
  • K. Butterbach-Bahl
  • P. Boeckx
Research areas and keywords

Subject classification (UKÄ) – MANDATORY

  • Earth and Related Environmental Sciences

Keywords

  • ForestDNDC-tropica Nitrous oxide Nitric oxide Sensitivity analysis Tropical forest Acrisols Alisols Cambisols Nyungwe Rwanda
Original languageEnglish
Pages (from-to)41-49
JournalGeoderma Regional
Volume03-feb
Publication statusPublished - 2014
Publication categoryResearch
Peer-reviewedYes
Externally publishedYes