Carbon sequestration by plant species used in green roofs across different periods

This study evaluated the influence of three plant species and two periods on the amount of carbon stored in the substrate in an extensive green roof. The study was carried out in March and September 2020 at Charles Darwin Business Garage Building, Recife, Pernambuco state, Brazil. A completely randomized design with a split-plot scheme was adopted, with plant species (zoysia grass [Zoysia japonica], inch plant [Tradescantia zebrina], and fountain grass [Pennisetum setaceum]) allocated to plots and the material collection periods (March and September) to subplots. The CO2 and organic carbon concentrations in the substrate were quantified. Thirty samples were obtained from the substrate during each period. No statistically significant difference was observed in CO2 content among species treatments; however, there was a significant difference between the two periods evaluated, with average values of 14.05 and 96.97 mg in March and September, respectively. Therefore, September has the greatest potential for CO2 storage in the substrate. Significant differences were observed in organic carbon concentrations among species and between periods, with average values of 95.05 and 129.22 g kg(-1) for fountain grass and inch plant, respectively, and 131.15 and 100.81 g kg(-1) in March and September, respectively.