Journal cover Journal topic
Biogeosciences An interactive open-access journal of the European Geosciences Union
Journal topic
Volume 12, issue 20
Biogeosciences, 12, 6071–6083, 2015
https://doi.org/10.5194/bg-12-6071-2015
© Author(s) 2015. This work is distributed under
the Creative Commons Attribution 3.0 License.
Biogeosciences, 12, 6071–6083, 2015
https://doi.org/10.5194/bg-12-6071-2015
© Author(s) 2015. This work is distributed under
the Creative Commons Attribution 3.0 License.

Research article 26 Oct 2015

Research article | 26 Oct 2015

Soil microbial nutrient constraints along a tropical forest elevation gradient: a belowground test of a biogeochemical paradigm

A. T. Nottingham1, B. L. Turner2, J. Whitaker3, N. J. Ostle4, N. P. McNamara3, R. D. Bardgett5, N. Salinas6,7,8, and P. Meir1,9 A. T. Nottingham et al.
  • 1School of Geosciences, University of Edinburgh, Drummond Street, Edinburgh, EH8 9XP, UK
  • 2Smithsonian Tropical Research Institute, Apartado 0843-03092, Balboa, Ancon, Republic of Panama
  • 3Centre for Ecology & Hydrology, Lancaster Environment Centre, Library Avenue, Lancaster, LA1 4AP, UK
  • 4Lancaster Environment Centre, Lancaster University, Bailrigg, Lancaster, LA1 4YQ, UK
  • 5Faculty of Life Sciences, Michael Smith Building, The University of Manchester, Oxford Road, Manchester, M13 9PT, UK
  • 6Seccion Química, Pontificia Universidad Católica del Peru, Lima, Peru
  • 7Universidad Nacional de San Antonio Abad del Cusco, Facultad de Biología, Cusco, Peru
  • 8Environmental Change Institute, School of Geography and the Environment, South Parks Road, Oxford, OX1 3QY, UK
  • 9Research School of Biology, Australian National University, Canberra, ACT 0200, Australia

Abstract. Aboveground primary productivity is widely considered to be limited by phosphorus (P) availability in lowland tropical forests and by nitrogen (N) availability in montane tropical forests. However, the extent to which this paradigm applies to belowground processes remains unresolved. We measured indices of soil microbial nutrient status in lowland, sub-montane and montane tropical forests along a natural gradient spanning 3400 m in elevation in the Peruvian Andes. With increasing elevation there were marked increases in soil concentrations of total N, total P, and readily exchangeable P, but a decrease in N mineralization determined by in situ resin bags. Microbial carbon (C) and N increased with increasing elevation, but microbial C : N : P ratios were relatively constant, suggesting homeostasis. The activity of hydrolytic enzymes, which are rich in N, decreased with increasing elevation, while the ratio of enzymes involved in the acquisition of N and P increased with increasing elevation, further indicating an increase in the relative demand for N compared to P with increasing elevation. We conclude that soil microorganisms shift investment in nutrient acquisition from P to N between lowland and montane tropical forests, suggesting that different nutrients regulate soil microbial metabolism and the soil carbon balance in these ecosystems.

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Short summary
We measured indices of soil microbial nutrient status in lowland, sub-montane and montane tropical forests along a natural gradient spanning 3400 m in elevation in the Peruvian Andes. We show that soil microorganisms shift investment in nutrient acquisition from P to N between lowland and montane tropical forests, suggesting that different nutrients regulate soil microbial metabolism and the soil carbon balance in these ecosystems.
We measured indices of soil microbial nutrient status in lowland, sub-montane and montane...
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