A community's urban forest is an important assets that provides innumerable social, environmental, and economic benefits. In fact, trees may be the only community asset that appreciates in value over time. Like any asset, though, trees require proper care and attention to maximize the value and benefits that they provide. Planning and assessment efforts, such as this project, can help raise awareness and develop strategies to optimize tree canopy throughout the community.
This analysis was designed to help document the urban forest for each community, quantify the value and benefits that it provides, and develop recommendations for future planting efforts. This study should be considered as a starting point—a springboard for conversations and opportunities that can enhance the tree canopy in each community. Based on this analysis, Davey Resource Group recommends the following:
1. PLANT NEW TREES
This study identified many tree planting opportunities in each community. To identify areas where municipal tree planting efforts could begin, communities should use the planting prioritization data and Story Mapto identify locations with a "High" or "Very High" priority planting rating. Communities should also encourage private property tree planting in business and industrial areas, as well as, within residential districts. Planting in these areas will help reduce stormwater runoff, and improve water quality.
The prioritized planting data and maps provide a great guideline for finding planting locations based on community goals, however, they do not take into account specific site factors, neighborhood preferences, or on-the-ground realities. Prior to planting, communities will need to assess these planting locations for factors that may limit a location’s suitability for trees.
Tree planting should follow the “right tree, right place” guideline (The Arbor Day Foundation). Before selecting a tree for planting, make sure it is the right tree—know how tall and wide it will be at maturity; and consider site factors such as road salt, soil conditions, or existing hardscape that might limit the suitability of a tree for a specific location.
In addition to "right tree, right place" communities should also consider species diversity when selecting tree species to plant. Communities with low tree species diversity (large number of trees of the same species) can suffer significant tree loss in the event of species-specific epidemics, such as the devastating results of Dutch elm disease (Ophiostoma novo-ulmi), emerald ash borer (Agrilus planipennis), oak wilt (Ceratocystis fagacaerum), and Asian longhorned beetle (Anoplophora glabripennis).
In general, the composition of a community's tree population should follow the 10-20-30 Rule for species diversity: a single species (e.g., red maple) should represent no more than 10% of the population, a single genus (e.g., maple) no more than 20%, and a single family (e.g., the soapberry family, which includes maple) no more than 30%.
Working with local partners or volunteer organizations, such as ReLeaf Michigan, can assist with increasing community canopy through tree planting. Additional strategies such as incentive and cost-share programs, grants, education and outreach, or policy changes can encourage residents and business owners to plant trees throughout the community.
2. PRESERVE EXISTING TREE CANOPY
It is important to note, that while tree planting is a component of increasing and improving tree canopy, it is not the only component. Older, larger trees contribute significantly more to the community’s current tree canopy than young, small trees. Caring for and preserving large trees should be an integral part of the community’s strategy to maximize the benefits provided by trees and ensure a sustainable canopy over time.
Unfortunately, trees do not live forever. They will need to be removed for a variety of reasons, including, natural mortality, invasive pest and disease outbreaks, extreme weather events, and development pressure, which can have a significant impact on community tree canopy. Communities are encouraged to keep an eye on their trees, including developing awareness of invasive pests, like Asian longhorned beetle and oak wilt, While hazardous trees can and should be removed, finding ways to encourage the retention and care of existing trees can substantially help the communities expand tree canopy. Community codes and policies should be examined to identify barriers or potential incentives to protecting and expanding tree canopy. Review of internal policies and procedures and how public work projects impact trees can also be helpful when identifying ways to preserve and protect existing canopy. Small changes in the design of public projects, including sidewalk installation, street and infrastructure improvements, can often significantly improve impacts to tree canopy. Many people do not fully understand how important trees are to their property and community. Outreach and education campaigns—including volunteer programs—can encourage citizens to care for and retain existing trees. Involving citizens in these community tree initiatives is a great way to spread the word on the benefits of trees and develop a “culture of trees” that can have significant long-term impacts on tree canopy across the community.
3. MEASURE CANOPY CHANGES ON A REGULAR BASIS
This project provided a rigorous tree canopy analysis that provided detailed information and ways to increase canopy coverage. As initiatives are undertaken to care for existing trees and plant new ones, the community will want to track progress and re-evaluate efforts towards meeting community goals. While a rigorous tree canopy analysis provides useful, detailed information, communities can perform less rigorous, self-assessments to track canopy changes using the i-Tree Canopy tool. We recommend assessing the tree canopy every 5 years using i-Tree canopy. For information on using this tool, please visit the i-Tree Canopy Analysis page.
This report represents one way in which urban tree canopy data can be analyzed. The communities are encouraged to continue to use this data and additional datasets to analyze relationships and connections that can help develop community objectives, understand challenges, and frame urban forest management decisions.