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Leaf senescence and resorption as mechanisms of maximizing photosynthetic production during canopy development at N limitation
Article first published online: 13 DEC 2002
DOI: 10.1046/j.1365-2435.2002.00674.x
1365-2435/asset/cover.gif?v=1&s=571713c051a4c9b4843f1aa4a484de7ca8661854 "Functional Ecology")
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How to Cite
Franklin, O. and Ågren, G. I. (2002), Leaf senescence and resorption as mechanisms of maximizing photosynthetic production during canopy development at N limitation. Functional Ecology, 16: 727–733. doi: 10.1046/j.1365-2435.2002.00674.x
Publication History
- Issue published online: 13 DEC 2002
- Article first published online: 13 DEC 2002
- Received 20 December 2001;revised 20 May 2002;accepted 30 May 2002
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Keywords:
- Canopy N distribution;
- litter production;
- optimal LAI model;
- resorption efficiency
Summary
- 1A canopy N distribution model optimizing photosynthesis was combined with mechanisms for senescence and N resorption to predict canopy leaf area index (LAI) development as a function of canopy nutrient content, Nc.
- 2Shedding of leaves at the bottom of the canopy was initiated when it increased canopy photosynthesis, through resorption and redistribution of N from lost leaves. The amount of N resorbed was modelled as a fraction (Rf) of the N in the leaf prior to senescence.
- 3For a fixed Nc, the LAI at which leaf shedding was initiated was calculated for different Rfs for canopies of Amaranthus cruentus, Glycine max, Oryza sativa and Sorghum bicolor.
- 4Predicted LAIs exceeded optimal LAIs estimated without leaf shedding and N resorption. LAI increased with increasing Rf. For all four species, the model closely predicted the observed LAIs with Rf = 0·7.
- 5Area-based resorption efficiency increased and litter N concentration decreased with increasing LAI and average canopy N concentration (mol N m−2 leaf). A reduction of Rf, e.g. in response to increased soil N availability, decreases resorption efficiency.
- 6The model provides a mechanistic basis for interpreting plant nutrient–resorption–LAI relations.