Investments that protect and enhance a city's green infrastructure, which includes trees, soil, living snow fences and other plant cover, deliver many financial, energy, heat island, quality of life and carbon sequestration benefits, just as do investments in a city's traditional grey infrastructure of roads and utilities (sewer, gas, electric and telecommunication lines). People love and gravitate toward tree-lined streets. Given a limited city budget, which always includes money for streets, the most effective expenditure of funds to improve a street would probably be on trees, funded through the street fund and augmented by storm water funding, as trees and vegetated infiltration can typically be worked into the street right-of-way.
Use of trees is an optional measure in the Minnesota Green Communities criteria, used by the Minnesota Housing Finance Agency in awarding funding for building affordable green multi-family housing.
The environmental, economic, and human health benefits of ash trees in Minnesota have been quantified. According to the National Tree Benefit Calculator, a 20-inch diameter ash tree near a residence provides benefits worth $197/yr. When these benefits are weighed against the cost to purchase, plant, prune, protect, and eventually remove a tree, the benefits outweigh the costs by a margin of about three to one. The dollars spent to remove and replace one average-sized city ash tree could instead be used to preserve, for over 20 years, 2 ash trees that will provide four times the tree benefits of the one replacement tree.
The National Tree Benefit Calculator shows the financial and environmental benefits individual trees provide, and the USDA Forest Service iTree Design tool shows the best place to plant a tree and the benefits that tree will provide over time.
The USDA Forest Service i-Tree tools offer a variety of state-of-the-art, peer-reviewed software that help communities measure tree canopy cover and the value of community trees for energy savings, stormwater management, carbon sequestration, air pollution reductions, and property value enhancement. A 2018 Trees & Stormwater calculator helps city staff make the case for using trees in stormwater management.
Trees and vegetative cover need healthy, undisturbed soils, or disturbed soils improved with compost to support vigorous plant growth resulting from the soil ecosystem services of rainfall infiltration and storage, adsorption of excess nutrients, filtration of sediments, biological decomposition of pollutants, and moderation of temperatures. Common development practices include removal of topsoil during grading and clearing, compaction of remaining soil, and planting into unimproved soil or shallow depths of poor quality imported topsoil. These conditions typically increase long-costs, producing unhealthy plants that die prematurely and need replacement, and that require excessive water, fertilizers and pesticides that contaminate runoff and increase associated costs of repairing impaired waters.
A 2017 publication by USDA Forest Service researchers quantifies the residential building energy conservation and avoided power plant emissions by urban and community trees in the United States. In Minnesota, the benefits include:
Estimated energy savings of 325,500 MWh and associated value of $35,100,000 statewide due to trees around residential buildings.
Avoided emissions from power plants for the state of 1,077,000 (metric) tons CO2, 1,300 tons NOx, 1,632 tons SO2, 33 tons PM2.5, 23 tons PM10, and 5 tons VOC.
Among 2005 U.S. Forest Service studies are data showing that single trees in southern or central Minnesota can generate a net benefit (total benefits minus initial and annual maintenance costs) of $160 - $3,040 during a 40-year period. The nearly 200,000 public trees in Minneapolis alone provide a total gross annual benefit of $24.9 million. Benefits analyzed are:
Energy savings and reduced CO2 emissions. Shading/wind breaks reduce residential energy used in air conditioning and heating (25% in summer and 20% in winter).
Increased property values and rents. Humans are hard-wired to value the natural world and will pay 9% more for a house with a tree within 50 feet. Properly placed trees can increase property values from 7-21% and buildings in wooded areas rent more quickly and tenants stay longer.
Improved retail sales in tree-rich commercial districts. People have been found to spend up to 12% more on products if they are shopping in a district with mature trees.
Increased life of asphalt. Shading reduces degradation of paved road surfaces by 40-60%.
Reduced stormwater runoff and improved water quality. Old growth trees can decrease runoff by 59%.
Improved air quality. Trees filter pollutants: 90 lbs. of CO2, 3 lbs. of particulates and 4 lbs. of ozone per large tree per year. A recent study estimated that in 2010, trees in the urban areas of Minnesota removed 4,600 tons of pollutants from the air and that this resulted in $26.7 million in reduced health care costs.
Improved wildlife habitat. Trees provide nesting places and food for birds and other animals that make up a well-functioning ecosystem.
Reduced crime. One study demonstrated that apartment buildings with high levels of greenery had 52% fewer crimes than those without greenery.
Noise reduction. Trees absorb sound. According to a North Carolina State University report, a well-placed tree can reduce noise by as much as 40%.