by DE Pataki, HR McCarthy, E Litvak, S Pincetl
Ecological Applications 21(3):661-6772011
There are very few in-situ studies of urban forest transpiration, despite the importance of this topic for management and planning. Here sap flow was measured in 15 species at six locations around Los Angeles. These data were used to estimate whole-tree and plot-level transpiration. There were very large differences in transpiration across species, ranging from Pinus canariensis in an unirrigated site (3.2 kg/tree/day) to Platanus hybrida (176 kg/tree/day; 55x higher). Other species with high levels of transpiration included Ficus microcarpa, Gleditsia triacanthos, and Platanus racemosa. In contrast, Brachychiton populneus, B. discolor, Sequoia sempervirens, and Eucalyptus grandis, despite their large sizes, showed low levels of transpiration. The results suggest that urban forests can be significant users of water, but thoughtful species choices and appropriate watering strategies can make a very large difference in the amount of water needed.