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In 2009, the City completed an inventory of street and park trees and found maple species comprise nearly 40% of the urban forest. This analysis does not include trees on private property or those in City-owned natural areas. City foresters are increasing tree diversity through re-planting programs.
Source: Ann Arbor Urban Forest Inventory |
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.
Why is diversity important to the health of the urban forest?
Diversity plays an important role in the long-term stability of an ecosystem. When an area has a high diversity of tree species, it is less likely to suffer catastrophic loss from diseases or pests. For example, consider the impact the Emerald Ash Borer (EAB) has had on Ann Arbor ash trees. The Emerald Ash Borer (Agrilus planipennis), an exotic wood-boring beetle discovered in southeast Michigan in the summer of 2002, has killed more than 10 million trees in southeast Michigan. Prior to the EAB infestation in 2003, ash trees comprised 17% of Ann Arbor's tree population. The EAB infestation resulted in the emergency removal of 10,000 ash trees that were planted along public sidewalks and in parks. Planting a diversity of hearty tree species throughout Ann Arbor neighborhoods can reduce the vulnerability of the urban forest to species-specific pests.
How is the City of Ann Arbor increasing tree diversity in the urban forest?
The City of Ann Arbor is increasing urban forest tree diversity through replanting efforts. More than 4,000 trees have been planted since 2004. In Fall 2010, an additional 705 trees were planted, with more planned plantings in the spring. An important component of the replanting strategy is a focus on diversifying the tree population by planting non-maple species.
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Last Updated: August 2009