The vertical distribution of nitrogen and photosynthetic activity at different plant densities in Carex acutiformis |
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Authors: | F Schieving T L Pons M J A Werger T Hirose |
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Institution: | (1) Department of Plant Ecology and Evolutionary Biology, University of Ultrecht, Sorbonnelaan 16, 3584 CA Utrecht, The Netherlands;(2) Biological Institute, Faculty of Science, Tohoku University, 980 Sendai, Japan |
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Abstract: | Shoots of the monocotyledonous perennial Carex acutiformis were grown in open (28 shoots m−2) and dense stands (280 shoots m−2). For fully grown stands the distribution of relative PPFD and leaf nitrogen per unit leaf area over canopy depth was determined.
Light response of photosynthesis was measured on leaf segments sampled at various heights in the stands. Relations between
parameters of these curves and leaf nitrogen were investigated.
Simulations showed that in the open stand daily canopy photosynthesis was not affected by nitrogen redistribution in the canopy.
For the dense stand however, a uniform nitrogen distribution would lead to only 73% of the maximum net carbon gain by the
stand under optimal nitrogen distribution. The actual canopy photosynthesis was only 7% less than this theoretical maximum;
the actual nitrogen distribution of the dense stand clearly tended to the optimal distribution. The vertical pattern of the
nitrogen distribution was to a large extent determined by the minimum leaf nitrogen content. The relatively high minimum leaf
nitrogen content found for Carex leaves may perhaps be necessary to maintain the physiological function of the basal parts
of the leaves. |
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Keywords: | canopy photosynthesis Carex acutiformis optimal nitrogen distribution |
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