Sedum-dominated green-roofs in a semi-arid region increase CO2concentrations during the dry season.
Green roofs are expected to absorb and store carbon in plants and soils and thereby reduce the high CO2concentration levels in big cities. Sedum species, which are succulent perennials, are commonly used in extensive green roofs due to their shallow root system and ability to withstand long water deficiencies. Here we examined CO2fixation and emission rates for Mediterranean Sedum sediforme on green-roof experimental plots. During late winter to early spring, we monitored CO2concentrations inside transparent tents placed over 1m2plots and followed gas exchange at the leaf level using a portable gas-exchange system. We found high rates of CO2emission at daytime, which is when CO2concentration in the city is the highest. Both plot- and leaf-scale measurements showed that these CO2emissions were not fully compensated by the nighttime uptake. We conclude that although carbon sequestration may only be a secondary benefit of green roofs, for improving this ecosystem service, other plant species than Sedum should also be considered for use in green roofs, especially in Mediterranean and other semi-arid climates.
The Kadas Green Roofs Ecology Center, Institute of Evolution and Department of Evolutionary and Environmental Biology, University of Haifa, Mt Carmel, 3498838, Israel. Electronic address: harelagra@gmail.com.
Har'el
H
Agra
Department of Plant & Environmental Sciences, Weizmann Institute of Science, Rehovot 76100, Israel.
Tamir
T
Klein
The Kadas Green Roofs Ecology Center, Institute of Evolution and Department of Evolutionary and Environmental Biology, University of Haifa, Mt Carmel, 3498838, Israel.
Amiel
A
Vasl
The Kadas Green Roofs Ecology Center, Institute of Evolution and Department of Evolutionary and Environmental Biology, University of Haifa, Mt Carmel, 3498838, Israel.
Hadar
H
Shalom
The Kadas Green Roofs Ecology Center, Institute of Evolution and Department of Evolutionary and Environmental Biology, University of Haifa, Mt Carmel, 3498838, Israel; Environmental Research Group, Sustainability Research Institute, University of East London, London E16 2RD, UK.
Gyongyver
G
Kadas
The Kadas Green Roofs Ecology Center, Institute of Evolution and Department of Evolutionary and Environmental Biology, University of Haifa, Mt Carmel, 3498838, Israel.
Leon
L
Blaustein
D002245:Carbon Dioxide / Q000032:analysis*; D057965:Carbon Sequestration; D002947:Cities; D017753:Ecosystem; D007557:Israel; D012621:Seasons; D031963:Sedum / Q000254:growth & development*
D002245:Carbon Dioxide
CO(2) domes; Carbon fixation; Carbon sequestration; Ecosystem services; Living roofs