by MW Strohbach, E Arnold, D Hasse
Landscape and Urban Planning 104(2):220-2292012
This study is the first to analyze the carbon life cycle of an urban green space project. A 2.16 ha greenbelt in Leipzig, Germany, was the focus of this project. All CO2 sinks and sources for a 50-year period were considered. Carbon sources included delivery of the trees, excavation of the holes, transport of workers to the site for planting and ongoing maintenance, the delivery and eventual burning of the support stakes, removal of pruned materials, lawn mowing, and trees that are felled for safety reasons and dead trees. Carbon sinks include the 461 trees planted on site. The carbon footprints of four alternative design scenarios were also calculated to see how this affected the results. The alternative scenarios included fewer or no trees with groundcovers requiring more or less intensive maintenance. All scenarios involving trees, including the actual project, showed a positive carbon footprint (i.e., sequestration exceeded emissions) for the 50-year period, ranging from 14 to 223 t CO2e/ha depending on tree mortality and growth. (The two scenarios involving only lawn and no trees had a negative carbon footprint.) The paper concludes with recommendations for maintenance and planning that can reduce emissions and describes uncertainties in the life-cycle analysis.