A climate-driven switch in plant nitrogen acquisition within tropical forest communities

doi:10.1073/pnas.0609935104

A climate-driven switch in plant nitrogen acquisition within tropical forest communities

Departments of ^†Ecology and Evolutionary Biology and
^§Geosciences, Princeton University, Princeton, NJ 08544; and
^¶Department of Botany, University of Florida, Gainesville, FL 32611

Edited by Robert Howarth, Cornell University, Ithaca, NY, and accepted by the Editorial Board March 29, 2007 (received for review November 9, 2006)

Abstract

The response of tropical forests to climate change will depend on individual plant species' nutritional strategies, which have not been defined in the case of the nitrogen nutrition that is critical to sustaining plant growth and photosynthesis. We used isotope natural abundances to show that a group of tropical plant species with diverse growth strategies (trees and ferns, canopy, and subcanopy) relied on a common pool of inorganic nitrogen, rather than specializing on different nitrogen pools. Moreover, the tropical species we examined changed their dominant nitrogen source abruptly, and in unison, in response to precipitation change. This threshold response indicates a coherent strategy among species to exploit the most available form of nitrogen in soils. The apparent community-wide flexibility in nitrogen uptake suggests that diverse species within tropical forests can physiologically track changes in nitrogen cycling caused by climate change.

Footnotes

^‡To whom correspondence may be sent at the present address:
Department of Biological Sciences, Stanford University, or Department of Global Ecology, Carnegie Institution of Washington, Stanford, CA 94305.
E-mail: houlton{at}stanford.edu
Author contributions: B.Z.H., D.M.S., and L.O.H. designed research; B.Z.H., D.M.S., and L.O.H. performed research; B.Z.H., D.M.S., and L.O.H. contributed new reagents/analytic tools; B.Z.H., D.M.S., E.A.G.S., and L.O.H. analyzed data; and B.Z.H., D.M.S., and L.O.H. wrote the paper.
The authors declare no conflict of interest.
This article is a PNAS Direct Submission. R.H. is a guest editor invited by the Editorial Board.
This article contains supporting information online at www.pnas.org/cgi/content/full/0609935104/DC1.
Abbreviations:

DON,

dissolved organic nitrogen;

MAP,

mean annual precipitation.