Leaf age and season influence the relationships between leaf nitrogen, leaf mass per area and photosynthesis in maple and oak trees |
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Authors: | P. B. REICH M. B. WALTERS D. S. ELLSWORTH |
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Affiliation: | Department of Forestry, 1630 Linden Drive, University of Wisconsin-Madison, Madison, WI53706, U.S.A. |
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Abstract: | Abstract. Seasonal changes in photosynthesis, leaf nitrogen (N) contents and leaf mass per area (LMA) were observed over three growing seasons in open-grown sun-lit leaves of red maple ( Acer rubrum ), sugar maple ( A. sacchamm ) and northern pin oak ( Quereus ellipsoidalis ) trees in southern Wisconsin. Net photosynthesis and leaf N were highly linearly correlated on both mass and area bases within all species from late spring until leaf senescence in fall. Very early in the growing season leaves had high N concentrations, but low photosynthetic rates per unit leaf N, suggesting that leaves were not fully functionally developed at that time. Leaf N per unit area and LMA had nonparallel seasonal patterns, resulting in differing relationships between leaf N/area and LMA in the "early versus late growing season. As a result of differences in seasonal patterns between leaf N/area and LMA, net photosynthesis/area was higher for a given LMA in the spring than fall, and the overall relationships between these two parameters were poor. |
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Keywords: | leaf development leafage photosynthesis nitrogen leaf mass per area maple oak |
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