Home > Research > Publications & Outputs > Using High-Resolution Data to Assess Land Use I...

Electronic data


Text available via DOI:

View graph of relations

Using High-Resolution Data to Assess Land Use Impact on Nitrate Dynamics in East African Tropical Montane Catchments

Research output: Contribution to Journal/MagazineJournal articlepeer-review

  • Suzanne R. Jacobs
  • Björn Weeser
  • Alphonce C. Guzha
  • Mariana C. Rufino
  • Klaus Butterbach-Bahl
  • David Windhorst
  • Lutz Breuer
<mark>Journal publication date</mark>1/03/2018
<mark>Journal</mark>Water Resources Research
Issue number3
Number of pages19
Pages (from-to)1812-1830
Publication StatusPublished
<mark>Original language</mark>English


Land use change alters nitrate (NO3-N) dynamics in stream water by changing nitrogen cycling, nutrient inputs, uptake and hydrological flow paths. There is little empirical evidence of these processes for East Africa. We collected a unique 2 year high-resolution data set to assess the effects of land use (i.e., natural forest, smallholder agriculture and commercial tea plantations) on NO3-N dynamics in three subcatchments within a headwater catchment in the Mau Forest Complex, Kenya's largest tropical montane forest. The natural forest subcatchment had the lowest NO3-N concentrations (0.44 ± 0.043 mg N L−1) with no seasonal variation. NO3-N concentrations in the smallholder agriculture (1.09 ± 0.11 mg N L−1) and tea plantation (2.13 ± 0.19 mg N L−1) subcatchments closely followed discharge patterns, indicating mobilization of NO3-N during the rainy seasons. Hysteresis patterns of rainfall events indicate a shift from subsurface flow in the natural forest to surface runoff in agricultural subcatchments. Distinct peaks in NO3-N concentrations were observed during rainfall events after a longer dry period in the forest and tea subcatchments. The high-resolution data set enabled us to identify differences in NO3-N transport of catchments under different land use, such as enhanced NO3-N inputs to the stream during the rainy season and higher annual export in agricultural subcatchments (4.9 ± 0.3 to 12.0 ± 0.8 kg N ha−1 yr−1) than in natural forest (2.6 ± 0.2 kg N ha−1 yr−1). This emphasizes the usefulness of our monitoring approach to improve the understanding of land use effects on riverine N exports in tropical landscapes, but also the need to apply such methods in other regions.