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Measure, Manicure and Marvel: Managing Parks Trees and Vacant Lots As Critical Public Infrastructure within a Resurging Legacy City Parks System.

This project explores two themes for the City of Detroit’s General Services Department, who is presently managing a rapid infusion of parks-related capital improvement projects. This study sought to identify incremental approaches to managing and growing Detroit’s urban canopy and tree cover on existing park land (currently 6.5% of the City’s overall tree canopy). The study also explored ways the City’s vacant lot mowing program, which is responsible for mowing an estimated 40 square miles of non-contiguous vacant land in the City, might begin to establish greater programmatic flexibility in the face of climate change.

Project Area

Detroit Parks for People and Trees.
Detroit, MI is a majority Black city of 670,000 residents covering 141 square miles of land in Southeast Michigan. The project area is the City’s parks system, which includes 289 city parks. The City’s median park size is 2.4 acres; presently only five parks within the system are over 100 acres. A thoughtful and well-timed Parks Master Plan update in 2017 has driven investment into the parks system for the first time in decades.

Although the park system is low on formally managed natural areas, roughly 60,000 City- owned residential vacant lots (or 37 square miles of land in in aggregate) provide some of the nature based solutions that open space can offer within an urban setting. The City’s General Services Department is currently responsible for mowing these 60,000 vacant lots. However, no city agency considers itself the steward of these lands. Detroit is located in USDA Hardiness Zone 6, along an important flyway for migrating birds, and within the Eastern Deciduous Forest Biome.

Management Goals

Management Goal 1: Maintain clean, inviting parks in every Detroit neighborhood.


1. Manage park trees as part of Detroit's overall urban forest (10 years).

2. Increase percent of tree planting associated with park land towards climate-informed species goals (5 years).

Management Goal 2: Maintain vacant lots as grassland for public health and safety through citywide maintenance.


1. Implement a change to existing vacant lot stewardship of four cuts a year (5 years).

2. Identify, execute, evaluate, and scale pilot initiatives to test alternative and high impact approaches to land care (5 years).

Climate Change Impacts

For this project, the most important anticipated climate change impacts include:
Low-diversity systems are at greater risk due to climate change.
The frequency of intense precipitation will continue to increase across the Midwest.
Seasonal variation in soil moisture and altered precipitation may influence the magnitude and duration of flood events.
The annual frost-free season is expected to increase by roughly 30 days in the Midwest by the end of the century.
Climate change will amplify many existing stressors to forest ecosystems in the Midwest, such as invasive species, insect pests and pathogens, and disturbance regime.
For Urban Canopy: Warming temperatures, drought, excessive precipitation and shifting climate zone will contribute to the adaptability of current and future tree species.
For Mowing and Stewardship of the City’s Vacant Land: Existing landscape conditions are diverse.

Challenges and Opportunities

Climate change will present challenges and opportunities for accomplishing the management objectives of this project, including:


Increased storms events, pests and pest response may divert attention to more immediate need of fallen tree management.
Extremely limited staff resources to coalesce partners and direct external capacity.
Mowing season may increase in duration due to lengthened shoulder seasons and reduced duration of winter; increased spring precipitation may create the need for a specific increase in spring mowing, and make mowing very difficult given the mud factor.
Increased days of extreme heat may trigger more local air quality regulations, limiting the ability of widescale mowing to occur with such persistence and flexibility.


Reduced need for winter management may create opportunity for re-allocation of budget to vendor-supported role in data collection.
There is a growing understanding regarding the relationship between the lack of equity in cities and the quality of tree canopy in a neighborhood.
Many partners are at the table to support and advise.
Vacant lots are actually a highly diverse landscape type within Detroit, offering an extreme range of soil types and a disturbance-adapted set of plant species.
Air quality restrictions could refocus a "participatory budgeting" style conversation within lower density neighborhoods around where and how to use the "mowing budget" for that neighborhood.
Re-prioritize part of winter parks maintenance budget to warm season maintenance. Consider criteria for new park design and improvements around the creation of lawn.
Modify existing non-programmed lawn in parks to other landscape types in part to increase the diversity of the park system.
Consider: (1) increased level of service to understand changes in safety, resident satisfaction, blight tickets; property sales / building permits.
Consider: (2) attempt to intersperse new plantings / shift species mix.
Consider: (3) change to maintenance protocol for purposes of habitat and preserving resident site lines.

Adaptation Actions

Project participants used the Adaptation Workbook to develop several adaptation actions for this project, including:

Parks + Canopy
Begin parks tree maintenance program, starting with 40+ already improved parks, including mulching and pruning.
Establish a park system wide tree species inventory created through partnerships that rely upon city staff expertise, contractors, mission aligned organizations and volunteer / resident contributions.
Increase the percent of tree planting associated with park land towards climate-informed species goals: Create internal tool to translate NIACS recommendations around species into city procurement and vendor recommendations for planting design.
Communicate the value and contribution of parks trees to Detroit's overall urban forest to recruit funding for tree maintenance and improvement: Begin formally tracking impacts of climate change on Departmental operations.
Do no harm and introduce flexibility: Consider re-naming the City’s mowing program to make space for other land care activities.
Do no harm and introduce flexibility: Adjust timing and/or scope of mowing contracts, including preparation and submission for City Council approval.
Do no harm and introduce flexibility: Diversify the tools: pilot alternative mowing strategies through neighborhood-level ‘participatory (mowing) budgeting.’


Project participants identified several monitoring items that could help inform future management, including:
The number of parks receiving capital improvement resources.
The budget per acre for maintenance and improvements (seeking to diversify *both* sources and uses).
Impact of weather on O&M for the parks system (start simply by capturing observations from frontlines staff at the end of the warm and cold seasons).

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Forest threats
Management plan
Management topics

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