Characterization of urban trees and shrubs for particulate deposition, carbon sequestration and BVOC emissions

There is a considerable potential to further develop the beneficial use of vegetation to promote urban environmental quality and citizen health. For this, basic knowledge of plant and vegetation traits are required. In this context, the ranking of species ability to capture particulate matter (PM), emission of photochemical trace gases, such as the biogenic volatile organic compound (BVOC) isoprenoids by trees and shrubs, and photosynthesis can be used to optimize vegetation designs for urban settings. Trees and shrubs were compared for PM accumulation on the surface and in the wax layer of leaves at sites located in Stavanger, Norway. The PM on the leaves, presented as PM10, PM2.5 and PM0.2 differed between the tested species by about 5 fold at the test site. The differences between species in PM deposition seem to be largest when the pollution concentrations are highest. Studies in Italy show that ornamental tree species vary in BVOC emission. However, of 14 ornamental broadleaf species, only Liquidambar styraciflua was recorded as substantially higher than the other tested species (greater than 10 µg g leaf dry weight-1 h-1) in BVOC emission. The types of isoprenoids released were also documented for the different species and the results will be discussed related to climate effects. The trees examined were quite different in photosynthetic capacity, with the lowest net CO2 assimilation recorded in Koelreuteria paniculata and the highest in Fraxinus ornus.