Trees are useful to the urban environment because they help cool the atmosphere of the city. The cooling effect of trees is an alternative solution to reduce the costs of air condition and to overall save money. Although trees are beneficial as they can reduce the temperature of warming climate, some trees have better cooling effect than others within cities of certain temperature range. Planting the right tree in the right location is critical to maximizing the efficiency of the trees ability to reduce temperature in warming climates. Not all types of trees have the same cooling effects and the heat tolerance for tree survival could be an issue in seasonal climates (Jenerette et al., 2007). The question arises to which tree will benefit urban environment most? Or How do we determine what species of trees is suitable for the conditions in urban areas? A study was done to determine the temperature of the upper regions of trees through a simple data set. This data provided a comparison between the trees within the streets of the city Basel and the trees within the parks.
The experiment "Tree surface temperature in an urban environment" was lead by Sebastian Leuzinger along with Roland Vogt and Christian Korner. It was conducted in the city Basel, Switzerland. Leuzinger and his colleagues performed the experiment using a high definition thermal camera and a helicopter. On July 16 2004, the helicopter was flown over the city Basel and the thermal camera was used to record the temperature of the city between the times of 11:44 and 12:10 CET (This was done to reduce the shadows created by the trees). The experiment was conducted in the temperature of 298.25K (25.1 degree Celsius). From the observations, Leuzinger was able to differentiate the specific temperature of trees and other objects like rooftops and bodies of water. A thermal image illustrated trees being in the temperature range of 1K below mean air temperature (trees in parks) to 4K above mean air temperature (trees on streets). The rooftops of houses were at 45 degree Celsius and the bodies of water were at around 18 Degree Celsius. Trees with lower foliage temperature would cool their environment more than trees with warmer temperature (Leuzinger et al., 2009).
According to the experiment presented, it did not specify exactly who did what during the experiment and what was contributed by whom. Instead it was assumed that Leuzinger and his colleagues worked together to produce the results of the experiment. From the results of the analysis, it was shown that trees with particularly smaller leaves have a lower surface temperature than trees with larger leaves (leaves with bigger surface area). This information helped to conclude that urban environments require more trees with smaller leaves to aid in the cooling of cities at high temperatures.
Trees with small leaves such as Roinia pseudoacacia and Pinus sylvestris have relatively low temperature in Basel and it would be recommended to have more of these species of trees within the cities of Basel. The trees’ effect for cooling may rely on factors such as the anatomy of the leaf of a tree. From the work done by Sebastian Leuzinger and his colleagues, the leaves from the trees are an important factor to investigate when trying to determine the right species of trees to have within a warming urban climate. Methods to help support urban vegetation may be to grow trees on top of rooftops to allow the reduction in temperature and to ease the complaints of human discomfort.
As the result of this experiment, we can acknowledge that the work done by Leuzinger, Vogt and Korner was an important message that illustrates how crucial it is to have urban vegetation. Trees are the solution to not only recycle the air quality but also to provide a cooler atmosphere within the urban environment.
Reference
Leuzinger S., Vogt R., Korner C., 2009. Trees surface temperature in an urban environment. Agriculture and Forest meteorology 150, 56-62.
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