Autumnal photosynthesis is extended in nitrogen-fixing European black alder compared with white basswood: possible adaptive significance

I. A. Neave, J. O. Dawson, E. H. Delucia

Research output: Contribution to journalArticle


Net photosynthesis was measured from late September to mid-November on leaves of actinorhizal Alnus glutinosa and nonactinorhizal Tilia heterophylla growing in C Illinois. Black alder retained its leaves and continued to photosynthesize for a month longer than white basswood. Maximum photosynthetic rates occurred in September and declined during the autumn for both species, although weekly values fluctuated widely. Mean maximum CO2 fixation rates for black alder and white basswood were 11.88 and 4.62 μmol CO2 . m-2.s-1, respectively, at the initial measurement in late September. On each subsequent weekly measurement date black alder had a significantly higher rate of CO2 fixation than basswood. Night temperatures of 0°C and below caused a sharp decline in photosynthesis for black alder on the following day. Stomatal conductance was highly correlated with photosynthesis, but as these 2 parameters declined over the autumn, intercellular CO2 concentration increased. Thus, nonstomatal limitations are thought to be involved in the temperature-induced reduction in photosynthesis. Prolonged photosynthesis in autumn may give black alder a competitive growth advantage over other deciduous species, compensate for the high energy cost associated with N fixation, or be associated with black alder's inefficient conservation of foliar N via autumnal retranslocation. -Authors

Original languageEnglish (US)
Pages (from-to)12-17
Number of pages6
JournalCanadian Journal of Forest Research
Issue number1
StatePublished - Jan 1 1989


ASJC Scopus subject areas

  • Global and Planetary Change
  • Forestry
  • Ecology

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