Photosynthetic rates in relation to leaf phosphorus content in pioneer versus climax tropical rainforest trees |
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Authors: | D Raaimakers R G A Boot P Dijkstra S Pot |
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Institution: | (1) Department of Plant Ecology and Evolutionary Biology, Utrecht University, P.O. Box 800.84, 3508 TB Utrecht, The Netherlands;(2) Tropenbos Office, Lot 12E Garnettstreet, Campbellville, Georgetown, Guyana;(3) AB-DLO, P.O. Box 14, 6700 AA Wageningen, The Netherlands;(4) Present address: Programa de Manejo Sostenible de Bosques Tropicales, 107 Casilla, Riberalta, Beni, Bolivia |
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Abstract: | In Guyana dense rainforest occurs on intensely weathered acid soils, low in soil phosphorus. To investigate whether low P availability limits photosynthesis of trees growing on these soils more than N does, leaf P and N content, and their relationship with the photosynthetic capacity (A
sat, mol CO2 m-2 s-1) were studied for nine pioneer and climax tree species in a range of light climates. Light environment was described using hemispherical photographs. For both pioneer and climax species, leaf P content (r
2=0.71 and 0.23, respectively) is a more important determinant of A
sat than leaf N content (r
2=0.54 and 0.12, respectively). Pioneer species have a higher leaf P and N content than climax species. At similar P or N content, pioneers have a higher A
sat than climax species. The saplings studied had a relatively high A
sat, considering their low P concentration (15–30 mol P g-1). All species studied had a constant leaf P and N concentration and photosynthetic capacity across light climates, because specific leaf mass (g m-2) increased similarly with light availability. This acclimation to a change in light environment makes a possible limitation of A
sat by P or N independent of light environment. |
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Keywords: | Climax tree species Phosphorus Photosynthesis Pioneer tree species Tropical rainforest |
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