Air Quality and Climate Change Trees literally help us breathe easier. They are major producers of oxygen and reduce the amount of carbon in the atmosphere by sequestering it in new growth every year. As a young tree grows, it adds to the volume of its wood at an accelerated rate. Mature trees store more carbon than younger trees by holding it in the accumulated wood that it maintains. Newly planted trees, with a faster growth rate than older trees, can offer valuable carbon sequestration. But the amount of carbon sequestered is increased with the size and health of trees as they re-skin each year. So, we need a robust supply of both young and mature trees to improve air quality and mitigate climate change. The Montgomery County government prioritized both the retention of and establishment of trees and forests in the county Climate Action Plan, published in 2021. Our county government considers retention and planting of trees and forests as a nature-based solution to help reduce harmful greenhouse gas emissions. One acre of forest absorbs six tons of carbon dioxide and produces four tons of oxygen. This is enough to meet the annual needs of 18 people. xxxi Threats to individual tree species from climate change have been summarized by the Climate Change Response Network. xxxii Our entire metro region is in a non-attainment zone for federal air quality standards. Poor air quality is a direct result of tree cover loss and poor land use and transportation decisions. For every 10,000 miles driven in a vehicle that gets 20 mpg, planting 15 trees can offset the CO 2 production, according to the Maryland Department of Natural Resources. xxxiii
In addition to reducing carbon emissions through sequestration, trees and forests reduce the heat island effect. xxxiv Elevated temperature from the heat island effect, particularly in urban areas, increases energy consumption, elevates production of greenhouse gas emissions, adds to problems with urban stormwater runoff and compromises human health. Trees cool our communities. They are an effective mitigation strategy when planted in strategic locations around buildings or to shade pavement in parking lots and on streets. In addition, the evaporative process of transpiration cools down the area near a tree. Small groups of trees have a compounding cooling effect. Research has shown that planting deciduous trees on the west side of a building is typically most effective for cooling the building, especially if trees shade windows and part of the building roof. xxxv Health, Social and Psychological Benefits of Trees
The image above shows the role of trees in air quality and the ecosystem. Image credit: Casey Trees
A long-recognized benefit of trees has been borne out in numerous studies. Abundant tree canopy can alleviate stress and anxiety and provide an overall better sense of wellbeing. Research has shown that, in areas where there is easy access to nature, physical health and
52
Made with FlippingBook Online newsletter maker