Trees leafing out shows us the transition from winter to spring. It is easy to take trees for granted but studies show that they provide numerous values. Here are the four ways why having trees around is important:

1.)    To provides cooler and greener city streets

You will see a few trees in urban landscapes as it is not regarded as a part of it. The major tree-planting campaign during the 1870s in New York City was led by Stephen Smith, a known physician, who believed that trees could save us during heat waves because it provides shade.

This campaign took decades to win support from the legislature of the state, but the New Yorkers joined the campaign. In 1897 they formed committees to plant trees in from of numerous homes, public schools and tenement blocks.

 "For these early activists planting trees was a way to cool streets and buildings in the summer and beautify the city's gritty urban landscape," observes Harvard University landscape architecture professor Sonja Dümpelmann.

"Only later would scientists come to realize the enormous potential that urban trees besides entire forests held in mitigating the effects of climate change."

2.)    It held down the Great Plains

In the 1930s the CCC members planted around 3 billion trees in the U.S national forests and it stretched from North Dakota to Texas. Young men were asked to work during the Great Depression and their tasks, as President Franklin Roosevelt stated, would be of definite and practical value.

This is due to the dust storms that were ravaging the Great Plains, and their mission was to converse soil. Trees held vulnerable soil in place. The CCC also reseeded U.S national forest across the United States.

3.)    It improves air and water quality

Many city planners see trees as an investment that is valuable. Theodore Endreny, a professor of engineering at the State University of New York's College of Environmental Science and Forestry, wanted to put a specific figure on the said value, so he and his research team calculated it.

"Trees clean the air and water, reduce stormwater floods, improve building energy use and mitigate climate change, among other things," Endreny writes. "For every dollar invested in planting, cities see an average US$2.25 return on their investment each year."

The team created a software package called the -Tree Tools that can be accessed for free. This software can estimate how trees will help combat air pollution and flooding and how it can build energy use and emit carbon dioxide in a community. They found out that trees provide benefits in large cities such as Mexico, Cairo and Beijing. These cities house more than 10 million people.

4.)    It makes streets safer

Most city streets plant trees in small pits found in the sidewalk, and it is mainly for shade and decoration. Anne Lusk, a research scientist at the Harvard T.H. Chan School of Public Health, believes that trees can do much more as they create transportation barriers for bikes and cars.

Lusk and her team found out through a Boston survey that people preferred streets with rows of trees or bushes as it separates cycle tracks and sidewalks from the street. Those who participated in the survey said that it makes them feel cooler, safer and less exposed to the pollution that cars emit.

Lusk also believes that urban trees should be kept healthy as their roots could trade nutrients and they can redesign the drainage system to distribute water to tree roots.

"It is time to put equal effort into designing green streets for bicyclists, pedestrians, bus riders and residents who live on transit routes, as well as for drivers," she writes.