Leaf canopy as a dynamic system: Ecophysiology and optimality in leaf turnover

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187 Citations (Scopus)


• Background and Aims: In a leaf canopy, there is a turnover of leaves; i.e. they are produced, senesce and fall. These processes determine the amount of leaf area in the canopy, which in turn determines canopy photosynthesis. The turnover rate of leaves is affected by environmental factors and is different among species. This mini-review discusses factors responsible for leaf dynamics in plant canopies, focusing on the role of nitrogen. • Scope: Leaf production is supported by canopy photosynthesis that is determined by distribution of light and leaf nitrogen. Leaf nitrogen determines photosynthetic capacity. Nitrogen taken up from roots is allocated to new leaves. When leaves age or their light availability is lowered, part of the leaf nitrogen is resorbed. Resorbed nitrogen is reutilized in new organs and the rest is lost with dead leaves. The sink-source balance is important in the regulation of leaf senescence. Several models have been proposed to predict response to environmental changes. A mathematical model that incorporated nitrogen use for photosynthesis explained well the variations in leaf lifespan within and between species. • Conclusion: When leaf turnover is at a steady state, the ratio of biomass production to nitrogen uptake is equal to the ratio of litter fall to nitrogen loss, which is an inverse of the nitrogen concentration in dead leaves. Thus nitrogen concentration in dead leaves (nitrogen resorption proficiency) and nitrogen availability in the soil determine the rate of photosynthesis in the canopy. Dynamics of leaves are regulated so as to maximize carbon gain and resource-use efficiency of the plant.

Original languageEnglish
Pages (from-to)521-533
Number of pages13
JournalAnnals of botany
Issue number3
Publication statusPublished - 2005


  • Canopy photosynthesis
  • Canopy structure
  • Cost-benefit analysis
  • Evolutionarily stable strategy
  • Leaf area index
  • Leaf lifespan
  • Leaf senescence
  • Leaf turnover
  • Nitrogen resorption
  • Nitrogen turnover
  • Nitrogen use efficiency
  • Optimality model

ASJC Scopus subject areas

  • Plant Science


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