Articles | Volume 11, issue 13
Biogeosciences, 11, 3661–3683, 2014
Biogeosciences, 11, 3661–3683, 2014

Research article 09 Jul 2014

Research article | 09 Jul 2014

On the potential vegetation feedbacks that enhance phosphorus availability – insights from a process-based model linking geological and ecological timescales

C. Buendía1,2,3, S. Arens1, T. Hickler4,5,6, S. I. Higgins6,7, P. Porada1, and A. Kleidon1 C. Buendía et al.
  • 1Biospheric Theory and Modelling Group, Max Planck Institute for Biogeochemistry, Hans-Knöll Str. 10, 07745 Jena, Germany
  • 2Bayreuth Academy of Advanced African Studies, University of Bayreuth, Hugo-Rüdel-Str. 10, 95445 Bayreuth, Germany
  • 3Ecological Modelling, University of Bayreuth, Dr.-Hans-Frisch-Str. 1–3, 95448 Bayreuth, Germany
  • 4Biodiversity and Climate Research Centre (LOEWE BiK-F), Senckenberganlage 25, 60325 Frankfurt am Main, Germany
  • 5Senckenberg Research Institute and Natural History Museum, Senckenberganlage 25, 60325 Frankfurt am Main, Germany
  • 6Institute of Physical Geography, Goethe-University, Altenhöferallee 1, 60438 Frankfurt am Main, Germany
  • 7Department of Botany, University of Otago, 479 Great King Street, 9016 Dunedin, New Zealand

Abstract. In old and heavily weathered soils, the availability of P might be so small that the primary production of plants is limited. However, plants have evolved several mechanisms to actively take up P from the soil or mine it to overcome this limitation. These mechanisms involve the active uptake of P mediated by mycorrhiza, biotic de-occlusion through root clusters, and the biotic enhancement of weathering through root exudation. The objective of this paper is to investigate how and where these processes contribute to alleviate P limitation on primary productivity. To do so, we propose a process-based model accounting for the major processes of the carbon, water, and P cycles including chemical weathering at the global scale. Implementing P limitation on biomass synthesis allows the assessment of the efficiencies of biomass production across different ecosystems. We use simulation experiments to assess the relative importance of the different uptake mechanisms to alleviate P limitation on biomass production. We find that active P uptake is an essential mechanism for sustaining P availability on long timescales, whereas biotic de-occlusion might serve as a buffer on timescales shorter than 10 000 yr. Although active P uptake is essential for reducing P losses by leaching, humid lowland soils reach P limitation after around 100 000 yr of soil evolution. Given the generalized modelling framework, our model results compare reasonably with observed or independently estimated patterns and ranges of P concentrations in soils and vegetation. Furthermore, our simulations suggest that P limitation might be an important driver of biomass production efficiency (the fraction of the gross primary productivity used for biomass growth), and that vegetation on old soils has a smaller biomass production rate when P becomes limiting. With this study, we provide a theoretical basis for investigating the responses of terrestrial ecosystems to P availability linking geological and ecological timescales under different environmental settings.

Final-revised paper