Ecosystems

, Volume 3, Issue 2, pp 193–209

Effects of Soil Texture on Belowground Carbon and Nutrient Storage in a Lowland Amazonian Forest Ecosystem

  • Whendee L.  Silver
  • Jason  Neff
  • Megan  McGroddy
  • Ed  Veldkamp
  • Michael  Keller
  • Raimundo  Cosme

DOI: 10.1007/s100210000019

Cite this article as:
Silver, W., Neff, J., McGroddy, M. et al. Ecosystems (2000) 3: 193. doi:10.1007/s100210000019

ABSTRACT

Soil texture plays a key role in belowground C storage in forest ecosystems and strongly influences nutrient availability and retention, particularly in highly weathered soils. We used field data and the Century ecosystem model to explore the role of soil texture in belowground C storage, nutrient pool sizes, and N fluxes in highly weathered soils in an Amazonian forest ecosystem. Our field results showed that sandy soils stored approximately 113 Mg C ha-1 to a 1-m depth versus 101 Mg C ha-1 in clay soils. Coarse root C represented a large and significant ecosystem C pool, amounting to 62% and 48% of the surface soil C pool on sands and clays, respectively, and 34% and 22% of the soil C pool on sands and clays to 1-m depth. The quantity of labile soil P, the soil C:N ratio, and live and dead fine root biomass in the 0–10-cm soil depth decreased along a gradient from sands to clays, whereas the opposite trend was observed for total P, mineral N, potential N mineralization, and denitrification enzyme activity. The Century model was able to predict the observed trends in surface soil C and N in loams and sands but underestimated C and N pools in the sands by approximately 45%. The model predicted that total belowground C (0–20 cm depth) in sands would be approximately half that of the clays, in contrast to the 89% we measured. This discrepancy is likely to be due to an underestimation of the role of belowground C allocation with low litter quality in sands, as well as an overestimation of the role of physical C protection by clays in this ecosystem. Changes in P and water availability had little effect on model outputs, whereas adding N greatly increased soil organic matter pools and productivity, illustrating the need for further integration of model structure and tropical forest biogeochemical cycling.

Key words: roots; soil carbon; century model; soil texture; biogeochemistry; tropics. 

Copyright information

© Springer-Verlag New York Inc. 2000

Authors and Affiliations

  • Whendee L.  Silver
    • 1
  • Jason  Neff
    • 3
  • Megan  McGroddy
    • 1
  • Ed  Veldkamp
    • 4
  • Michael  Keller
    • 2
  • Raimundo  Cosme
    • 5
  1. 1.Department of Environmental Sciences, Policy, and Management, University of California, 151 Hilgard Hall, Berkeley, California 94720, USA US
  2. 2.The International Institute of Tropical Forestry, USDA Forest Service, Call Box 25000 Rio Piedras, Puerto Rico 00928, USA US
  3. 3.Department of Biological Sciences, Stanford University, Stanford, California 94305-5020, USA US
  4. 4.Institut fuer Bodenkunde und Waldernaehrung, Universitaet Goettingen, Buesgenweg 237077 Goettingen, Germany DE
  5. 5.EMBRAPA Amazônia Oriental, Santarém, Pará, Brazil BR