Oecologia

, Volume 76, Issue 2, pp 222–235

Nutrient dynamics within amazonian forests

II. Fine root growth, nutrient availability and leaf litter decomposition
  • Elvira Cuevas
  • Ernesto Medina
Original Papers

DOI: 10.1007/BF00379956

Cite this article as:
Cuevas, E. & Medina, E. Oecologia (1988) 76: 222. doi:10.1007/BF00379956

Summary

Relationships between fine root growth, rates of litter decomposition and nutrient release were analysed in a mixed forest on Tierra Firme, a Tall Amazon Caatinga and a Low Bana on podsolized sands near San Carlos de Rio Negro. Fine root growth in the upper soil layers (root mat+10 cm upper soil) was considerably higher in the Tierra Firme forest (1117 g m-2 yr-1) than in tall Cattinga (120) and Bana (235). Fine root growth on top of the root mat was stimulated significantly by added N in Tall Caatinga and Low Bana forests, by P in Tierra Firme and Bana forests, and by Ca only in the Tierra Firme forest. Rate of fine root growth in Tierra Firme forest on fresh litter is strongly correlated with the Mg and Ca content of litter. Rate of litter decomposition was inversely related to % lignin and the lignin/N ratio of litter. Litter contact with the dense root mat of the Tierra Firme increased rates of disappearance for biomass, Ca and Mg as compared with litter permanently separated or lifted weekly from the root mat to avoid root attachment. Nitrogen concentration of decomposing litter increased in all forests, net N released being observed only in Caryocar glabrum and Aspidosperma megalocarpum of the Tierra Firme forest after one year of exposure. Results emphasize the differences in limiting nutrients in amazonian forest ecosystems on contrasting soil types: Tierra Firme forests are particularly limited by Ca and Mg, while Caatinga and Bana forests are limited mainly by N availability.

Key words

Amazonian forestsRoot growthNutrient releaseOrganic matter decomposition

Copyright information

© Springer-Verlag 1988

Authors and Affiliations

  • Elvira Cuevas
    • 1
  • Ernesto Medina
    • 1
  1. 1.Centro de EcologíaIVICCaracasVenezuela