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Forskningsartikel2022Vetenskapligt granskadÖppen tillgång

Limits to photosynthesis: seasonal shifts in supply and demand for CO2 in Scots pine

Stangl, Zsofia R.; Tarvainen, Lasse; Wallin, Goran; Marshall, John D.


Boreal forests undergo a strong seasonal photosynthetic cycle; however, the underlying processes remain incompletely characterized. Here, we present a novel analysis of the seasonal diffusional and biochemical limits to photosynthesis (A(net)) relative to temperature and light limitations in high-latitude mature Pinus sylvestris, including a high-resolution analysis of the seasonality of mesophyll conductance (g(m)) and its effect on the estimation of carboxylation capacity (VCmax). We used a custom-built gas-exchange system coupled to a carbon isotope analyser to obtain continuous measurements for the estimation of the relevant shoot gas-exchange parameters and quantified the biochemical and diffusional controls alongside the environmental controls over A(net). The seasonality of A(net) was strongly dependent on VCmax and the diffusional limitations. Stomatal limitation was low in spring and autumn but increased to 31% in June. By contrast, mesophyll limitation was nearly constant (19%). We found that VCmax limited A(net) in the spring, whereas daily temperatures and the gradual reduction of light availability limited A(net) in the autumn, despite relatively high VCmax. We describe for the first time the role of mesophyll conductance in connection with seasonal trends in net photosynthesis of P. sylvestris, revealing a strong coordination between g(m) and A(net), but not between g(m) and stomatal conductance.


boreal forest; carboxylation capacity; diffusional limitations; light limitation; mesophyll conductance; Pinus sylvestris; stomatal conductance; temperature limitation

Publicerad i

New Phytologist
2022, Volym: 233, nummer: 3, sidor: 1108-1120
Utgivare: WILEY