Effects of species and rooting conditions on the growth and cooling performance of urban trees

摘要: The urban heat island (UHI) is a problem that likely to be exacerbated by ongoing climate change, but it often claimed trees can mitigate and hence adapt our cities change. Many researchers have attempted quantify the cooling effects of using modelling approaches. However, major disadvantage most models they consider all vegetation act as single saturated layer their effect merely proportional its surface cover. Therefore, fail take into account potential differences between tree species different environmental growing conditions.To address this issue four studies were conducted in Manchester, UK from February, 2010 December, 2012. compared growth abilities several commonly planted species, investigated range conditions: investigating soil compaction aeration also urbanization simulated change rooting zone. Overall, showed selection conditions substantially alter evapotranspirational provided trees.Fast such Pyrus calleryana, with dense wide canopy provide up 2.2 kW tree-1, 3-4 times Sorbus arnoldiana, which thinner narrower moderate rate. P. calleryana was under three contrasting cut-out pits pavements; grass verges; filled Amsterdam soil. Trees less compacted had grown almost twice fast those pavements better leaf physiological performance. Together longer season, uptake nutrients moisture, 7kW, 5 higher than pavements. Another experiment 3 standard planting techniques non-compacted load bearing soils or without permeable slabs optimum not only dependent on preventing ensuring covering materials are oxygen. open up-to 1 cooling, around 350 650 W small large covered respectively. Our final increase 20-30%; however, despite being more water stressed plots 40% sap flux density, potential. study suggested at least transpirational benefit might enhanced places like Manchester increased temperature future, potentially expense photosynthesis carbon gain.Together these show evaporative depends strongly both conditions. If incorporated regional local energy exchange results help us magnitude effectiveness greenspaces city adapting them