Carbon dynamics and greenhouse gas emissions in a tropical dry forest and a pre-alpine Bavarian grassland

• Author / Creator

  Calvo-Rodriguez, Sofia

• The present thesis contains three studies, all of which follow the main trend of quantification and assessment of carbon dynamics and greenhouse gas emissions. The main objectives of the first study “Dynamics of carbon sequestration in tropical dry forests along two successional gradients under climate change extremes” were to quantify biomass and carbon accumulation dynamics in two TDF during 12 years along a successional gradient, and assess how climatic events influenced the yearly carbon accumulation. The net primary productivity (NPP) of these TDF varied from 2 Mg C ha-1 y-1 to 7 Mg C ha-1 y-1, depending on the age of the forest stands. Climate variability and drought events like the ENSO of 2015 had a strong influence on carbon dynamics at both sites. The second study “Seasonality and budgets of soil greenhouse gas emissions from a tropical dry forest successional gradient in Costa Rica” main objectives were to evaluate seasonal variation and annual budgets of soil greenhouse gas emissions (CO2, N2O, and CH4) in a tropical dry forest successional gradient, and evaluate environmental factors that control temporal dynamics of greenhouse gas emissions. Annual soil emissions of CO2 were higher for the young forest (8555.7 kg C ha-1 y-1) followed by the older forest (7419.6 kg C ha-1 y-1) and the pasture (7223.7 kg C ha-1 y-1). Annual emissions of N2O were higher for the forest sites (0.39 and 0.43 kg N ha-1 y-1) and lower in the pasture (0.09 kg N ha-1 y-1). CH4 uptake was higher in the older forest (-2.61 kg ha-1 y-1) followed by the pasture (-0.69 kg C ha-1 y-1) and the young forest (-0.58 kg C ha-1 y-1). Fluxes were mainly positively influenced by soil moisture and microbial biomass, and negatively by soil temperature and ammonium concentrations. In the last chapter “Spatio-temporal variability and uncertainties of greenhouse gas emissions in a pre-alpine Bavarian grassland,” we compared measured soil gas emissions of CO2, N2O, soil temperature and water content against simulated values derived from the biogeochemical model LandscapeDNDC. For the CO2 emissions, soil temperature and water content, the model was able to simulate the daily average across different locations. We found a strong correlation between the modeled results and the measured emissions for CO2 (r=0.5, p<0.01). For N2O emissions, we found significant differences between measured emissions and modeled emissions.

• Subjects / Keywords

  • seasonality.
  • nitrous oxide
  • carbon dioxide
  • methane
  • soil greenhouse gases
  • tropical dry forest

• Graduation date

  Fall 2020

• Type of Item

  Thesis

• Degree

  Doctor of Philosophy

• DOI

  https://doi.org/10.7939/r3-ddhk-fw41

• License

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