Tree of the Week: A balance sheet
Urban trees are moneymakers. They return far more in value of benefits than they cost in maintenance. The publicly owned trees of our urban forest are major capital assets and a part of the commonly owned infrastructure, just like roads and utilities. Direct and indirect benefits of trees increase year after year, and their status should be regularly reviewed like any investment portfolio. It probably will not surprise you that aerial photographs of Los Angeles show that the wealthiest neighborhoods have the highest number of trees.
On the positive side, studies show that trees generate clear social, psychological, environmental and economic benefits. Leaves filter the air of harmful gaseous and particulate pollutants, and prevent corresponding uptake into our bodies, the soil and the environment. The trees provide oxygen and reduce air conditioning, electricity generation and fuel (coal, oil, gas) needs. They shade and cool homes and cities, blacktop and pavement; reduce the urban heat island effect; sequester carbon dioxide; moderate climate change; and create a pleasant ambient atmosphere.
Trees break the force of the wind and extend the life of paved surfaces. They intercept rainfall, reduce erosion, protect streams, allow for smaller, less expensive drainage infrastructure improvements (storm drains) while they improve water quality, filter storm runoff water, reduce erosion and transport of sediment in streams, slow runoff to river and ocean and allow increased groundwater recharge.
Trees provide flowers, fruit, food, fall color; offer a home to wildlife and migratory birds; connect us to nature and the unseen-but-much-alive world underground; reduce stress, muscle tension and blood pressure; inspire and calm. They can change our perception of time, increase feelings of security, reduce road rage, improve our relationship with neighbors and make us recover faster from hospital stays. They increase property values by making homes more salable or more appealing to tenants and making retail businesses more attractive and inviting. They instill community pride, stimulate economic development and attract new business and tourism. Many trees are climate adapted and drought resistant and need little or no water once established; they are also basically self-repairing creatures.
On the cost side, their requirements are not big, but they cannot be ignored. Trees need to be properly selected, planted, staked, watered, pruned and shaped, as well as maintained by knowledgeable people. The right care will prevent most problems and diseases, but shortcuts will increase maintenance costs and may have disastrous effects that may not show up until years after the fact.
Photo credit: Pieter Severynen