Plant and Soil

, Volume 411, Issue 1, pp 243–259

Nitrogen turnover and greenhouse gas emissions in a tropical alpine ecosystem, Mt. Kilimanjaro, Tanzania

  • Adrian Gütlein
  • Marcus Zistl-Schlingmann
  • Joscha Nico Becker
  • Natalia Sierra Cornejo
  • Florian Detsch
  • Michael Dannenmann
  • Tim Appelhans
  • Dietrich Hertel
  • Yakov Kuzyakov
  • Ralf Kiese
Regular Article

DOI: 10.1007/s11104-016-3029-4

Cite this article as:
Gütlein, A., Zistl-Schlingmann, M., Becker, J.N. et al. Plant Soil (2017) 411: 243. doi:10.1007/s11104-016-3029-4

Abstract

Background and aims

Tropical alpine ecosystems are identified as the most vulnerable to global environmental change, yet despite their sensitivity they are among the least studied ecosystems in the world. Despite its important role in constraining potential changes to the carbon balance, soil nitrogen (N) turnover and plant availability in high latitude and high altitude ecosystems is still poorly understood.

Methods

Here we present a first time study on a tropical alpine Helichrysum ecosystem at Mt. Kilimanjaro, Tanzania, which lies at an altitude of 3880 m. Vegetation composition is characterized and major gross N turnover rates are investigated using the 15N pool dilution method for three different vegetation cover types. In addition greenhouse gas exchange (CO2, N2O and CH4) was manually measured using static chambers.

Results

Gross N turnover rates and soil CO2 and N2O emissions were generally lower than values reported for temperate ecosystems, but similar to tundra ecosystems. Gross N mineralization, NH4+ immobilization rates, and CO2 emissions were significantly higher on densely vegetated plots than on sparsely vegetated plots. Relative soil N retention was high and increased with vegetation cover, which suggests high competition for available soil N between microbes and plants. Due to high percolation rates, irrigation/rainfall has no impact on N turnover rates and greenhouse gas (GHG) emissions. While soil N2O fluxes were below the detection limit at all plots, soil respiration rates and CH4 uptake rates were higher at the more densely vegetated plots. Only soil respiration rates followed the pronounced diurnal course of air and soil temperature.

Conclusion

Overall, our data show a tight N cycle dominated by closely coupled ammonification-NH4+-immobilization, which is little prone to N losses. Warming could enhance vegetation cover and thus N turnover; however, only narrower C:N ratios due to atmospheric nitrogen deposition may open the N cycle of Helichrysum ecosystems.

Keywords

Soil N cycling Gross N turnover 15N pool dilution Greenhouse gas emission Tropical alpine ecosystem 

Copyright information

© Springer International Publishing Switzerland 2016

Authors and Affiliations

  • Adrian Gütlein
    • 1
  • Marcus Zistl-Schlingmann
    • 1
  • Joscha Nico Becker
    • 2
  • Natalia Sierra Cornejo
    • 3
  • Florian Detsch
    • 4
  • Michael Dannenmann
    • 1
  • Tim Appelhans
    • 4
  • Dietrich Hertel
    • 3
  • Yakov Kuzyakov
    • 2
    • 5
  • Ralf Kiese
    • 1
  1. 1.Institute of Meteorology and Climate Research, Atmospheric Environmental ResearchKarlsruhe Institute of TechnologyGarmisch-PartenkirchenGermany
  2. 2.Department of Soil Science of Temperate EcosystemsUniversity of GöttingenGöttingenGermany
  3. 3.Plant ecology and ecosystems researchUniversity of GöttingenGöttingenGermany
  4. 4.Environmental Informatics, Faculty of GeographyPhilipps-University MarburgMarburgGermany
  5. 5.Department of Agricultural Soil ScienceUniversity of GöttingenGöttingenGermany