Photosynthetic activity in three vascular species of Spitsbergen vegetation during summer season in response to microclimate

Abstract

Abstract Diurnal measurements of photosynthetic processes, effective quantum yield of photosystem II (ΦPSII), photosynthetic electron transport rate (ETR) were done in three dominant species of Arctic tundra (Silene acaulis, Dryas octopetala, Salix polaris) in Petuniabukta, Spitsbergen. Daily courses of net photosynthesis (PN) were calculated from chlorophyll fluorescence data and daily photosynthesis evaluated. The short-term field measurements were carried out in summer 2009, and 2010. Fluorometric parameters (ΦPSII and ETR) weremeasured each 5 minutes as well as microclimate characteristics of the site for 10 (2009) and 8 days (2010), respectively. In all species photosynthetic ETR was well related to incident photosynthetically active radiation and leaf temperature. In general, D. octopetala exhibited slightly lower ETR than the other two species. Estimated maximum photosynthetic rate (PNmax) reached 17.6, 21.4, and 22.9 μmol CO2 m-2 s-1 for S. polaris, S. acaulis, and D. octopetala, respectively. Daily photosynthesis reached comparable values in all species, D. otopetala, however, exhibited slightly lower values than the other two species both for overcast and fully sunny days (3.9 and 13.4 mmol CO2 m-2 d-1, respectively). The range of daily photosynthesis for S. polaris and S. acaulis studied, reached the ranges of 4.6-6.9 and 14.6-15.2 mmol CO2 m-2 d-1 for overcast and fully sunny day, respectively.