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Due to Emerald Ash Borer Infestation, the City is expected to lose 19% of its total tree canopy. However, the City is aggressively pursuing replanting lost trees.
Source: Ann Arbor Forestry |
The City of Ann Arbor, Michigan, is replanting more than 10,000 street and park street trees killed by the exotic wood-boring beetle , Emerald Ash Borer (EAB). The City recognizes the importance of replacing lost canopy. As resources are limited, every planting option is being explored.
Nearly a thousand public trees were planted in 2006 through these venues:
305 Street trees planted by city forestry crews with state grants paying for half of the tree costs. - 183 Street trees planted with volunteer Tree Teams coordinated by Global ReLeaf of Michigan with tree purchase support from the Dean Fund.
- 3 Downtown area street trees planted and funded by DDA.
- 72 Street trees planted through the city-approved Forestry Permit option funded by individuals. (112 total permits filed; 6 rejected initially as unsuitable plan for the location.)
- 358 Park trees planted with tree funding and labor from the Rotary Club of Ann Arbor in coordination with the City of Ann Arbor. (Does not include 246 trees planted by Rotarians in 2004-05.)
- 17 Fuller Park trees funded by MSU study grant.
- 3 Memorial park tree plantings funded by donors.
- 40 Park trees planted as part of the parks planning renovations.
981 TOTAL trees replanted in Ann Arbor streets and parks in 2006.
In 2006, Ann Arbor celebrated the 25th Anniversary of its Tree City USA designation, assigned by the National Arbor Day Foundation to cities with a commitment to maintain their urban forests, since about 1980, we have averaged about 1,050 new street and park tree plantings each year. Based on our street tree inventory, we have planted more trees than we have removed, partly due to the growth of Ann Arbor over the past 25 years. In 1980, our street tree population was 33,000 trees; today, it's 42,000.
Due to EAB infestation, the City has lost 19% of its total tree canopy. Prior to the EAB epidemic, we would typically remove about 500 street trees per year, which was a mortality rate of about 1% of the entire street tree population, and about 300 park trees. With EAB, we removed about 4,500 street trees alone last year. The street tree EAB removals are now complete.
What is an urban forest?
An urban forest is all of the woody vegetation growing in an urban area, including trees, shrubs, and vines found along city streets, public parks and private property. When the City uses the term urban forest, we are typically referring to the trees maintained by the City in public parks and lining the right-of-way along streets.
How does our urban forest affect the environment?
In Ann Arbor, streets constitute a large portion of the impervious cover. However, planting trees along streets can help improve the quality of our urban environment in a number of ways. Canopy cover also lowers the temperature in shaded areas. The use of street trees can reduce stormwater runoff by intercepting rain in their canopies and absorbing water through their root systems. Furthermore, street trees help reduce noise pollution by filtering noise and buffering wind. Aesthetically, street trees provide visual interest to pedestrians and motorists, as well as provide habitat for a variety of bird and animals species. Trees also have a positive effect on the environment by decreasing levels of pollutants in the air and are producers of oxygen. Perhaps the most important way that trees combat pollution is by acting as a sink or receptor and catching suspended particulate matter on its leaf surface. This helps remove a number of pollutants including nitrogen oxides, sulphur, ammonia and dust particles.
The Center for Urban Forest Research found that a 40 year-old green ash tree on public property provides the following annual environmental benefits:
- Intercepts over 2143 gallons of stormwater to reduce flooding and erosion
- Removes 2.5 lbs of air pollutants
- Conserves 7% of energy bills for cooling
- Adds 1% to the retail value of the average home
In 2001, urban trees across the United States stored 700 million tons of Carbon at a value of $14.3 billion, according to the USDA Forest Service.
Tell me more about Emerald Ash Borer.
Emerald ash borer (EAB), Agrilus planipennis Fairmaire, is an exotic beetle that was discovered in southeastern Michigan near Detroit in the summer of 2002. The adult beetles nibble on ash foliage but cause little damage. The larvae (the immature stage) feed on the inner bark of ash trees, disrupting the tree's ability to transport water and nutrients. Emerald ash borer probably arrived in the United States on solid wood packing material carried in cargo ships or airplanes originating in its native Asia. Emerald ash borer is also established in Windsor, Ontario, was found in Ohio in 2003, northern Indiana in 2004, and northern Illinois in 2006. Since its discovery, EAB has:
- Killed more than 20 million ash trees in Michigan, Ohio and Indiana. Most of the devastation is in southeastern Michigan.
- Caused regulatory agencies and the USDA to enforce quarantines (Ohio, Indiana, Michigan, Illinois, Maryland) and fines to prevent potentially infested ash trees, logs or firewood from moving out of areas where EAB occurs.
- Cost municipalities, property owners, nursery operators and forest products industries tens of millions of dollars.
Source: Emerald Ash Borer Information, by theUSDA Forest Service and partners
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