Oecologia

, Volume 139, Issue 4, pp 545–550

Belowground carbon cycling in a humid tropical forest decreases with fertilization

  • Christian P. Giardina
  • Dan Binkley
  • Michael G. Ryan
  • James H. Fownes
  • Randy S. Senock
Ecosystem Ecology

DOI: 10.1007/s00442-004-1552-0

Cite this article as:
Giardina, C.P., Binkley, D., Ryan, M.G. et al. Oecologia (2004) 139: 545. doi:10.1007/s00442-004-1552-0

Abstract

Only a small fraction of the carbon (C) allocated belowground by trees is retained by soils in long-lived, decay-resistant forms, yet because of the large magnitude of terrestrial primary productivity, even small changes in C allocation or retention can alter terrestrial C storage. The humid tropics exert a disproportionately large influence over terrestrial C storage, but C allocation and belowground retention in these ecosystems remain poorly quantified. Using mass balance and 13C isotope methods, we examined the effects of afforestation and fertilization, two land-use changes of large-scale importance, on belowground C cycling at a humid tropical site in Hawaii. Here we report that in unfertilized plots, 80% of the C allocated belowground by trees to roots and mycorrhizae was returned to the atmosphere within 1 year; 9% of the belowground C flux was retained in coarse roots and 11% was retained as new soil C. The gains in new soil C were offset entirely by losses of old soil C. Further, while fertilization early in stand development increased C storage in the litter layer and in coarse roots, it reduced by 22% the flux of C moving through roots and mycorrhizae into mineral soils. Because soil C formation rates related strongly to rhizosphere C flux, fertilization may reduce an already limited capacity of these forests to sequester decay-resistant soil C.

Keywords

Ecosystem carbon cycling Hawaii Rhizosphere respiration Soil surface CO2 efflux Soil carbon formation 

Copyright information

© Springer-Verlag 2004

Authors and Affiliations

  • Christian P. Giardina
    • 1
  • Dan Binkley
    • 2
  • Michael G. Ryan
    • 2
    • 3
  • James H. Fownes
    • 4
  • Randy S. Senock
    • 5
  1. 1.United States Department of Agriculture-Forest ServiceNorth Central Research StationHoughtonUSA
  2. 2.Department of Forest, Rangeland, and Watershed Stewardship and Graduate Degree Program in EcologyColorado State UniversityFort CollinsUSA
  3. 3.United States Department of Agriculture-Forest ServiceRocky Mountain Research StationFort CollinsUSA
  4. 4.Department of Natural Resources conservation, Holdsworth Natural Research CenterUniversity of MassachusettsAmherstUSA
  5. 5.Department of Natural Resources and Environmental ManagementUniversity of Hawai’i at ManoaHonoluluUSA

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