Unexpected changes in soil phosphorus dynamics along pasture chronosequences in the humid tropics

Alan R. Townsend, Gregory P. Asner, Cory C. Cleveland, Margaret E. Lefer, Mercedes M.C. Bustamante

Research output: Contribution to journalArticle

28 Scopus citations

Abstract

Phosphorus (P) is widely believed to limit plant growth and organic matter storage in a large fraction of the world's lowland tropical rain forests. We investigated how the most common land use change in such forests, conversion to cattle pasture, affects soil P fractions along pasture chronosequences in the central Brazilian Amazon and in southwestern Costa Rica. Our sites represent a broad range in rainfall, soil type, management strategies, and total soil P (45.2-1228.0 μg P/g soil), yet we found some unexpected and at times quite similar changes in soil P in all sites. In the Brazilian sites, where rainfall is relatively low and pasture management is more intense than in the Costa Rican sites, significant losses in total soil P and soil organic carbon (SOC) were seen with pasture age on already P-deficient Oxisol and Entisol soils. However, P losses were from inorganic soil P fractions, while organic forms of soil P remained constant or increased with pasture age, despite the declines in SOC. In Costa Rica, SOC remained constant across the Oxisol sites and increased from forest to pasture on the Mollisols, while soil organic P increased with pasture age in both sequences.

Original languageEnglish (US)
Pages (from-to)LBA 34-1-LBA 34-9
JournalJournal of Geophysical Research Atmospheres
Volume107
Issue number20
DOIs
StatePublished - 2002

Keywords

  • Land use change
  • Pastures
  • Phosphorus
  • Soils
  • Tropics

ASJC Scopus subject areas

  • Geophysics
  • Forestry
  • Oceanography
  • Aquatic Science
  • Ecology
  • Water Science and Technology
  • Soil Science
  • Geochemistry and Petrology
  • Earth-Surface Processes
  • Atmospheric Science
  • Earth and Planetary Sciences (miscellaneous)
  • Space and Planetary Science
  • Palaeontology

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