Fine root dynamics along an elevational gradient in tropical Amazonian and Andean forests

Research output: Contribution to journalArticle

Abstract

The key role of tropical forest belowground carbon stocks and fluxes is well recognised as one of the main components of the terrestrial ecosystem carbon cycle. This study presents the first detailed investigation of spatial and temporal patterns of fine root stocks and fluxes in tropical forests along an elevational gradient, ranging from the Peruvian Andes (3020 m) to lowland Amazonia (194 m), with mean annual temperatures of 11.8 degrees C to 26.4 degrees C and annual rainfall values of 1900 to 1560 mm yr(-1), respectively. Specifically, we analyse abiotic parameters controlling fine root dynamics, fine root growth characteristics, and seasonality of net primary productivity along the elevation gradient. Root and soil carbon stocks were measured by means of soil cores, and fine root productivity was recorded using rhizotron chambers and ingrowth cores. We find that mean annual fine root below ground net primary productivity in the montane forests (0-30 cm depth) ranged between 4.27 +/- 0.56 Mg C ha(-1) yr(-1) (1855 m) and 1.72 +/- 0.87 Mg C ha(-1) yr(-1) (3020 m). These values include a correction for finest roots (< 0.6 mm diameter), which we suspect are under sampled, resulting in an underestimation of fine roots by up to 31% in current ingrowth core counting methods. We investigate the spatial and seasonal variation of fine root dynamics using soil depth profiles and an analysis of seasonal amplitude along the elevation gradient. We report a stronger seasonality of NPPFineRoot within the cloud immersion zone, most likely synchronised to seasonality of solar radiation. Finally, we provide the first insights into root growth characteristics along a tropical elevation transect: fine root area and fine root length increase significantly in the montane cloud forest. These insights into belowground carbon dynamics of tropical lowland and montane forests have significant implications for our understanding of the global tropical forest carbon cycle.

Details

Authors
  • C. A. J. Girardin
  • L. E. O. C. Aragao
  • Y. Malhi
  • W. Huaraca Huasco
  • Dan Metcalfe
  • L. Durand
  • M. Mamani
  • J. E. Silva-Espejo
  • R. J. Whittaker
External organisations
  • University of Oxford
Research areas and keywords

Subject classification (UKÄ) – MANDATORY

  • Physical Geography
Original languageEnglish
Pages (from-to)252-264
JournalGlobal Biogeochemical Cycles
Volume27
Issue number1
Publication statusPublished - 2013
Publication categoryResearch
Peer-reviewedYes
Externally publishedYes