ECOLOGY/EVOLUTION

Limits From Leaf Litter

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Science  16 Jul 2004:
Vol. 305, Issue 5682, pp. 311
DOI: 10.1126/science.305.5682.311a

Macroecology aims to explain the broad-scale geographical patterns exhibited by living organisms, such as the distribution of vegetation types or species richness with latitude. Documentation of the patterns themselves, however, is often far from straightforward, impeding progress to mechanistic understanding. Reich and Oleksyn have completed a global survey of the nitrogen (N) and phosphorus (P) content of leaves of more than 1000 plant species. The availability of these two elements generally set the limits to plant growth, and their availability is thus a key determinant of vegetation structure and ecosystem properties. Even so, the complexity of interactions between temperature, soil nutrient content, soil age, and plant physiology makes it hard to predict what might be the geographical correlates of leaf nutrient stoichiometry. The findings suggest that at lower latitudes, where temperatures are higher, leaf N and P content declines and N:P ratios increase—consistent with the observation that P is the limiting nutrient in older tropical soils. In contrast, in younger temperate soils N is limiting. — AMS

Proc. Natl. Acad. Sci. U.S.A. 10.1073/pnas.0403588101 (2004).

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