Access

You are not currently logged in.

Access your personal account or get JSTOR access through your library or other institution:

login

Log in to your personal account or through your institution.

Facultative nitrogen fixation by canopy legumes in a lowland tropical forest

Alexander R. Barron, Drew W. Purves and Lars O. Hedin
Oecologia
Vol. 165, No. 2 (February 2011), pp. 511-520
Published by: Springer in cooperation with International Association for Ecology
Stable URL: http://www.jstor.org/stable/41500654
Page Count: 10
  • Download ($43.95)
  • Cite this Item
Facultative nitrogen fixation by canopy legumes in a lowland tropical forest
Preview not available

Abstract

Symbiotic dinitrogen (N₂) fixation is often invoked to explain the N richness of tropical forests as ostensibly N₂-fixing trees can be a major component of the community. Such arguments assume N₂ fixers are fixing N when present. However, in laboratory experiments, legumes consistently reduce N₂ fixation in response to increased soil N availability. These contrasting views of N₂ fixation as either obligate or facultative have drastically different implications for the N cycle of tropical forests. We tested these models by directly measuring N₂-fixing root nodules and nitrogenase activity of individual canopydominant legume trees (Inga sp.) across several lowland forest types. Fixation was substantial in disturbed forests and some gaps but near zero in the high N soils of mature forest. Our findings suggest that canopy legumes closely regulate N₂ fixation, leading to large variations in N inputs across the landscape, and low symbiotic fixation in mature forests despite abundant legumes.

Page Thumbnails

  • Thumbnail: Page 
[511]
    [511]
  • Thumbnail: Page 
512
    512
  • Thumbnail: Page 
513
    513
  • Thumbnail: Page 
514
    514
  • Thumbnail: Page 
515
    515
  • Thumbnail: Page 
516
    516
  • Thumbnail: Page 
517
    517
  • Thumbnail: Page 
518
    518
  • Thumbnail: Page 
519
    519
  • Thumbnail: Page 
520
    520