The Many Environmental Benefits Provided by Trees
Did you know that according to recent research planting trees worldwide is our most effective climate change solution to date? Recent research also shows that trees provide USD $505 million in annual benefits for a highly populated city. Ten highly populated cities around the world were studied to arrive at this estimate. This corresponded to USD $1.2 million per km2 of trees or USD $35 for each city resident. Some of the important environmental benefits of trees contributing to figures such as these are described below.
Urban Heat Island Effect
Urban environments typically have higher temperatures than surrounding rural areas due to the Urban Heat Island (UHI) effect. This effect is caused by various factors including the presence of materials like cement and asphalt which absorb more solar radiation then surfaces in rural areas. According to Health Canada the UHI effect “threatens over 30 million Canadians with much-increased heat risks” by exacerbating the risk posed by heatwaves in urban areas. Trees can significantly combat the UHI effect by providing shade and transpiring water from leaves resulting in reduced temperatures.
Air Pollution
According to one estimate for 2015 alone air pollution cost Canadians $36 billion and resulted in approximately 7,700 premature deaths. Trees filter air pollutants by absorbing these toxins through their leaves. Recent research studying the impacts of trees on air pollution in 86 Canadian cities for 2010 estimated, for each city, a range of $52.5 to $402.6 million for human health benefits, the avoidance of 7 to 54 cases of mortality, as well as 7,900 to 31,100 incidences of acute respiratory symptoms. These numbers grow large when multiplying by the above figures to arrive at estimates for all 86 urban areas considered in the study.
Climate Change
According to the Food and Agriculture Organization (FAO), “a mature tree can absorb up to 150 kg of CO2 per year”. Recent research in the journal Science uses satellite data to discover that space exists to plant trees in 0.9 billion hectares of land worldwide making this option a very significant, if not the best, climate change mitigation strategy. The study illustrates how much space for tree planting exists in different countries around the world and found Canada to be in the third position from the top with a potential of 78.8 million hectares of land for planting new trees. For comparison, Ontario is approximately 107.6 million hectares in size. According to the study’s senior author, Thomas Crowther (a climate change ecologist at the Swiss Federal Institute of Technology in Zurich), “This is by far — by thousands of times — the cheapest climate change solution”.
Reduced Flooding
Trees can reduce flooding in urban areas by intercepting and slowing releasing rainwater. Also, water evaporates from leaves instead of falling to the ground. In addition, the roots of a tree hold soil in place reducing the possibility of soil flowing into a water body (which increases the chances of flooding). Finally, trees create pores in the soil which allows rainwater to drain into the ground instead of washing off the surface. According to the FAO, a mature evergreen tree can intercept more than 15,000 litres of water per year.
Water Quality
Trees make it easier for contaminants to be brought into the soil and subsequently absorbed instead of entering water supply sources. This reduces the need for expensive water treatment facilities. Trees absorb toxic substances in surface runoff including metals (e.g. lead, cadmium, etc.) from industrial facilities and near roadways as well as pesticides from urban and rural sources. In addition, trees absorb nutrients such as nitrates and phosphates that are typically present from agricultural runoff.
How You Can Help
One way to help tree planting is by supporting politicians who encourage tree planting initiatives. You can also support the environment by planting trees on your property or by donating to tree planting initiatives. As planting a tree is one of the best and affordable ways to make a personal difference for the environment, consider supporting tree planting in your community.
