Spatial and temporal variability of urban tree canopy temperature during summer 2010 in Berlin, Germany
- 698 Downloads
Trees form a significant part of the urban vegetation. Their meteorological and climatological effects at all scales in urban environments make them a flexible tool for creating a landscape oriented to the needs of an urban dweller. This study aims at quantifying the spatio-temporal patterns of canopy temperature (T C) and canopy-to-air temperature difference (∆T C) in relation to meteorological conditions and tree-specific (physiological) and urban site-specific characteristics. We observed T C and ∆T C of 67 urban trees (18 species) using a high-resolution thermal-infrared (TIR) camera and meteorological measurements in the city of Berlin, Germany. TIR images were recorded at 1-min intervals over a period of 2 months from 1st July to 31st August 2010. The results showed that ∆T C depends on tree species, leaf size and fraction of impervious surfaces. Average canopy temperature was nearly equal to air temperature. Species-specific maximum ∆T C varied between 1.9 ± 0.3 K (Populus nigra), 2.9 ± 0.3 K (Quercus robur), 3.2 ± 0.5 K (Fagus sylvatica), 3.9 ± 1.0 K (Platanus acerifolia), 4.6 ± 0.2 K (Acer pseudoplatanus), 5.0 ± 0.5 K (A. platanoides) and 5.6 ± 1.1 K (A. campestre). We analysed ∆T C for a hot and dry period (A) and a warm and wet period (B). The range of species-specific ∆T C at noon was nearly equal, i.e. 4.4 K for period A and 4.2 K for period B. Trees surrounded by high fraction of impervious surfaces showed consistently higher ∆T C. Knowledge of species-specific canopy temperature and the impacts of urban structures are essential in order to optimise the benefits from trees in cities. However, comprehensive evaluation and optimisation should take the full range of climatological effects into account.
KeywordsStreet Canyon Leaf Size Impervious Surface Canopy Temperature Urban Tree
We would like to thank Petra Grasse (Institute of Meteorology, Freie Universität Berlin) for providing the cloud data and Jörn Welsch (Urban and Environmental Information System, Senate Department for Urban Development) for providing the impervious soil coverage map for Berlin. Especially we would like to thank Albert Polze, Britta Jänicke and Marco Otto for assistance in tree data collection and analysis.
- Brown R, Gillespie T (1990) Estimating radiation received by a person under different species of shade trees. J Arboric 16:158–161Google Scholar
- Celestian SB, Martin CA (2005) Effects of parking lot location on size and physiology of four southwest landscape trees. J Arboric 31:191–197Google Scholar
- Christen A, Meier F, Scherer D (2011) High-frequency fluctuations of surface temperatures in an urban environment. Theor Appl Climatol. doi: 10.1007/s00704-011-0521-x
- Foster JR (1992) Photosynthesis and water relations of the floodplain tree, boxelder (Acer negundo L.). Tree Physiol 11:199–149Google Scholar
- Jones HG (1992) Plants and microclimate. Cambridge University Press, CambridgeGoogle Scholar
- Körner C, Scheel JA, Bauer H (1979) Maximum leaf diffusive conductance in vascular plants. Photosynthetica 13:45–82Google Scholar
- Sandford AP, Jarvis PG (1986) Stomatal responses to humidity in selected conifers. Tree Physiol 2:89–103Google Scholar
- Senate Department for Urban Development (2007) Berlin digital environmental atlas 01.02 impervious soil coverage (sealing of soil surface). Database: Urban and Environmental Information System (UEIS). http://www.stadtentwicklung.berlin.de/umwelt/umweltatlas/e_text/ekb102.pdf. Accessed 21 Mar 2012
- Souch CA, Souch C (1993) The effect of trees on summertime below canopy urban climates: a case study. Bloomington, Indiana. J Arboric 19:303–312Google Scholar
- Streiling S, Matzarakis A (2003) Influence of single and small clusters of trees on the bioclimate of a city: a case study. J Aboric 29:309–316Google Scholar