Evaluation of macrophytes suitable for agriculture drainage treatment with respect to their carbon sequestration potential

Relationship between the phenolics content and the decomposition rate of Carex nigra, Scirpus sylvaticus, Phalaris arundinacea and Phragmites australis was evaluated in this study. The study was aimed at the selection of plants growing in the Czech Republic, that can be used for constructed wetlands treating agricultural runoff and that can also contribute to carbon sequestration. Plant decomposition was studied using the litterbag experiments lasting 365 days. One set of samples (each plant from three various location in four replicates) were taken after 81, 173, 301 and 365 days and decomposition rate was evaluated. The phenolics concentrations in aboveground biomass of selected macrophytes were varied in narrow range from 6.73 ± 1.26 g.kg−1 (leaves of P. arundinacea) to 14.09 ± 3.52 g.kg−1 (C. nigra). On the other hand, decomposition rate significantly varied among different plants and different plan parts as well. The close relationship between the concentrations of phenolics and decomposition rates was found for C. nigra, S. sylvaticus and leaves of P. arundinacea and P. australis in this study - the higher the phenolics concentration, the lower decomposition rate. The study also revealed a very strong relationship between total phenolics/total nitrogen ratio in the biomass, and therefore, the plants with high phenolics content would be more efficient in carbon sequestration. It is necessary to extend the research with the aim to find other plants naturally occurring in the Czech Republic characterized by high concentration of phenolics in the aboveground biomass, thus, having the potential of slow decomposition and high carbon sequestration.