Urban tree cover is beneficial to human health and well-being, but it is often unevenly distributed. It’s not just that trees look nice; they also provide a variety of other advantages for urban dwellers. During the summer, the shade and natural cooling they provide are appreciated by those nearby. Landsat imagery was used to investigate the connection between summertime surface temperatures and tree cover during the spring and summer months. Nearly two-thirds of the cities surveyed have less tree cover in poorer areas than wealthier ones (Gharahshir 17). 15.2 percent fewer trees and 1.50C higher average temperatures are found per capita in poorer neighborhoods. Because they have 30 percent less tree cover, affluent neighborhoods in some northeastern U.S.
Cities are 4 degrees Celsius hotter than their less wealthy neighbors. Income and tree cover have a positive correlation, even after controlling for population density and built-up intensity. It’s also linked to non-Hispanic whites. Estimates place the compensatory value of the 62 million fewer trees in low-income areas than in high-income regions at $56 billion. An additional $17.6 billion in tree planting and natural regeneration is needed to close the gap in tree cover and benefit 42 million low-income residents. As a result of a housing shortage, the federal government launched a program in 1933 to increase and separate the country’s housing stock. He argues that the government’s efforts benefited whites’ middle- and lower-middle-class citizens the most (McDonald 11). Residents of color were forced into urban housing projects because the new suburban communities would not accept them as members of their community. Segregation in our metropolitan areas has stagnated inequality because families cannot move up the economic ladder when they live in areas with fewer opportunities. In the investigation, no consideration was given to the health of humans. Heatstroke and other heat-related illnesses are more common when exposed to high temperatures for long periods. More than 200 New Deal-era maps of American cities were used to determine which neighborhoods were eligible for federal loans (Nowak). The grading system made it difficult for people of color, immigrants, and low-income families to get mortgages and build and maintain green urban spaces. It’s still hot in previously redlined areas where there aren’t as many trees to help keep the neighborhood cool after more than 50 years.
Trees are often planted in cities to help control the rising temperatures. However, scientists often have a hard time measuring their cooling effects due to their nature. Unfortunately, this method tends to reveal disappointing results. In most cases, the air temperature in parks is still more relaxed than in the streets. This is because the heat flows in these areas are different. Trees can also help cool the air by providing shade. They can also act like evapotranspiration by releasing solar heat (Hobbie 18). Trees help block out solar radiation by blocking it. They also contribute to the cooling of the surrounding area by preventing it from reaching our bodies. This means that their shade can reduce our body temperature by around 7 to 15 degrees Celsius. In summer, the cool shade provided by parks and other urban areas is enough to draw out the sun-loving people. Aside from these, trees can also help cool down buildings by blocking solar radiation from entering their walls. Studies in the U.S. have shown that the shade provided by trees can reduce air conditioning costs by up to 30%.
In contrast, air conditioning is still very prevalent in some parts of Europe. In 2003, a heatwave in Europe killed about 70,000 individuals. Researchers are now trying to determine if the trees’ shade can help lower the temperature in the apartment blocks and houses inhabited by the less well-off people (Egerer 8). During sunny periods, the air temperature in cities can reach 7 degrees Celsius higher than that of the countryside. This phenomenon occurs because the asphalt and brick surfaces of buildings absorb the solar radiation coming from the Sun. Urban trees can also counter solar radiation by intercepting it before reaching the ground. This method varies the effects of the Sun’s rays, which can cause water to evaporate from the leaves. Another type of evaluation that can be done about evapotranspiration is measuring the temperature difference between the tree canopy and the built surface. This method can tell if the temperature difference is significant enough to indicate that the leaves are cooling.
A better technique is to measure the water loss from a tree’s trunk or the sap flow using its leaves. This method can tell you how much water the plant is losing. The Callery pear tree can provide up to 6 kW of cooling. However, only after the tree is growing well can it provide the cooling effect needed. The effectiveness of Callery pears can be significantly affected by the environment they’re grown in. For instance, if the tree’s roots grow through poorly aerated soil, their transpiration rate can be reduced by up to five (Egerer 16). Understanding how much cooling effect a given tree can provide is crucial in developing a strategy to reduce air conditioning costs. Biologists, physicists, and engineers need to work together using regional climate models. Together, the scientists will try to find ways to use the urban forests to make cities more relaxed.
Works Cited
Egerer, Monika H., et al. “Temperature variability influences urban garden plant richness and gardener water use behavior, but not planting decisions.” Science of the Total Environment 646 (2019): 111-120.
Gharahshir, Mohammadreza. “Implementation of sustainable architecture patterns in hot and dry regions of Iran by investigating on vernacular sustainable architecture patterns.” (2019).
Hobbie, Sarah E., and Nancy B. Grimm. “Nature-based approaches to managing climate change impacts in cities.” Philosophical Transactions of the Royal Society B 375.1794 (2020): 20190124.
McDonald, Robert I., et al. “The tree cover and temperature disparity in US urbanized areas: Quantifying the association with income across 5,723 communities.” PloS one 16.4 (2021): e0249715.
Nowak, David J., Alexis Ellis, and Eric J. Greenfield. “The disparity in tree cover and ecosystem service values among redlining classes in the United States.” Landscape and Urban Planning 221 (2022): 104370.
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