Photosynthetic parameters of a sedge-grass marsh as a big-leaf: effect of plant species composition

The study estimates the parameters of the photosynthesis-irradiance relationship (P-N/I) of a sedge-grass marsh (Czech Republic, Europe), represented as an active green surface-a hypothetical big-leaf. Photosynthetic parameters of the big-leaf are based on in situ measurements of the leaf P-N/I curves of the dominant plant species. The non-rectangular hyperbola was selected as the best model for fitting the P-N/I relationships. The plant species had different parameters of this relationship. The highest light-saturated rate of photosynthesis (A(sat)) was recorded for Glyceria maxima and Acorus calamus followed by Carex acuta and Phalaris arundinacea. The lowest A(sat) was recorded for Calamagrostis canescens. The parameters of the P-N/I relationship were calculated also for different growth periods. The highest A(sat) was calculated for the spring period followed by the summer and autumn periods. The effect of the species composition of the local plant community on the photosynthetic parameters of the big-leaf was addressed by introducing both real (recorded) and hypothetical species compositions corresponding to wet and dry hydrological conditions. We can conclude that the species composition (or diversity) is essential for reaching a high A(sat) of the big-leaf representing the sedge-grass marsh in different growth periods.

Automated summary

The study estimated the parameters of the photosynthesis-irradiance relationship in a sedge-grass marsh in the Czech Republic, Europe, finding that different plant species have different parameters in this relationship. Sunlight-saturated photosynthesis rates vary among different plant species and growth periods, and species composition plays a crucial role in influencing the photosynthetic parameters of the big-leaf representing the marsh in different seasons.