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We measured the seasonal and temperature responses of leaf photosynthesis and respiration of two co-occurring native New Zealand tree species with contrasting leaf phenology: winter-deciduous fuchsia ( Fuchsia excorticata  J. R. Forst &amp; G. Forst) and annual evergreen wineberry ( Aristotelia serrata  J. R. Forst &amp; G. Forst). There was no difference in the amount of nitrogen per unit leaf area ( N  area , range 40–160 mmol m −2 ,  P  = 0.18) or specific leaf area ( S , range 8–27 m 2  kg −1 ,  P  = 0.87) in summer leaves of wineberry or fuchsia. The amount of nitrogen per unit leaf area and  S  varied significantly with height of leaves in the canopy for both species ( r  2  range 0.61–0.87). Parameters describing the maximum rates of rubisco carboxylation ( V  cmax ) and electron transport ( J  max ) were related significantly to  N  area , and were 60% higher on average in spring and summer leaves than in autumn and winter leaves for both species. The seasonal effect remained significant ( P  &lt; 0.001) when  N  area  was included in a regression model, indicating that seasonal changes were not only due to changes in  N  area . Values for  V  cmax  and  J  max  were 30% lower in wineberry leaves than in fuchsia leaves on average, although the difference ranged from 15% in summer leaves to 39% in autumn leaves. Activation energies describing the temperature dependence of  V  cmax  and  J  max  in wineberry were 111 and 114% of corresponding values for fuchsia ( E  a  ( V  cmax ) = 39.1 kJ mol −1 ,  E  a  ( J  max ) = 32.9 kJ mol −1 ). Respiration at night was the same ( P  = 0.34) at 10 °C for both species ( R  10  = 0.7 μmol m −2  s −1 ), although activation energies ( E  0 ) were higher in wineberry than in fuchsia (47.4 and 32.9 kJ mol −1  K −1 , respectively). These results show that rates of photosynthesis are higher in winter-deciduous fuchsia than in annual evergreen wineberry.

Seasonal and temperature dependence of photosynthesis and respiration for two co-occurring broad-leaved tree species with contrasting leaf phenology †