Global patterns of plant leaf N and P in relation to temperature and latitude
- *Department of Forest Resources, University of Minnesota, St. Paul, MN 55108-6112; and ‡Institute of Dendrology, Polish Academy of Sciences, 5 Parkowa, PL-62-035, Kórnik, Poland
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Communicated by G. David Tilman, University of Minnesota, St. Paul, MN, May 20, 2004 (received for review October 23, 2003)
Abstract
A global data set including 5,087 observations of leaf nitrogen (N) and phosphorus (P) for 1,280 plant species at 452 sites and of associated mean climate indices demonstrates broad biogeographic patterns. In general, leaf N and P decline and the N/P ratio increases toward the equator as average temperature and growing season length increase. These patterns are similar for five dominant plant groups, coniferous trees and four angiosperm groups (grasses, herbs, shrubs, and trees). These results support the hypotheses that (i) leaf N and P increase from the tropics to the cooler and drier midlatitudes because of temperature-related plant physiological stoichiometry and biogeographical gradients in soil substrate age and then plateau or decrease at high latitudes because of cold temperature effects on biogeochemistry and (ii) the N/P ratio increases with mean temperature and toward the equator, because P is a major limiting nutrient in older tropical soils and N is the major limiting nutrient in younger temperate and high-latitude soils.
Footnotes
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↵ † To whom correspondence should be addressed at: Department of Forest Resources, University of Minnesota, 1530 Cleveland Avenue North, 115 Green Hall, St. Paul, MN 55108-6112. E-mail: preich{at}umn.edu.
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Abbreviations: MAT, mean annual temperature; r 2, coefficient of determination.
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See Commentary on page 10849.
- Copyright © 2004, The National Academy of Sciences
