A paved trail with flowers runs through a forest

Forestry Management works to restore, enhance and manage the Park District's native forests and woodlands, and to develop natural landscapes for interpretive and developed recreation areas by planning, implementing and maintaining trees and landscape plantings throughout the park system.


Three Rivers is committed to restoring the environment, including planting forests. Most native forests in the region were cleared for agriculture by the turn of the twentieth century. Three Rivers is working to restore these plant communities.

Each year, 20-30 acres of parkland are prepared for reforestation around the Park District. In addition to new plantings, these reforestation efforts also include managing existing trees that are native to the area and removing invasive species. Tree plantings take two forms:

  • Large bareroot (10-12' tall) plantings – Approximately 12,000 large trees are installed and maintained on sites where rapid reforestation is desired.
  • Seedling (1-3' tall) plantings – Annually, 45,000 tree and shrub seedlings are installed. They are then protected and maintained for 20 or more years.

young trees in planters

In total, there are more than 400 successful reforestation sites that have been worked on around the Park District. Two examples of parks that host successful reforestation efforts are:

Hyland Lake Park Reserve

Hyland Lake Park Reserve is home to a 15 acre reforestation site. In 1994, seedlings from 27 different native tree species were planted in the park reserve. A six-foot electric fence was installed around the project site for the first ten years to exclude deer and protect the seedlings. Trees were planted at a density of 800 trees per acre.  Today, the trees are 7-12 inches in diameter and have an average height of 40 feet.

Carver Park Reserve

In 2009, a reforestation site was planted at Carver Park Reserve. The site spans 30 acres and seedlings from 24 different tree species were planted. The site is currently surrounded by a six-foot electric fence to exclude deer. Seedlings were planted at a density of 1,700 trees per acre. As of 2016, the trees were 2-4 inches in diameter with an average height of 15 feet.

Protecting Trees from Wildlife

Deer and other wildlife can damage the forests and landscape plantings around Three Rivers Park District. Our plant protection program reduces landscape damage by deer and other animals through population control efforts, the installation of deer fences and the use of deer repellents. The fences prevent deer from entering that area, which typically means their offspring will also avoid the area.
Three Rivers’ staff also continues to pursue options for preventing meadow vole and other small mammal population outbreaks, which can cause severe damage to tree and shrub plantings. To protect native species from small mammals, staff place shelters around the trunks of those trees and shrubs.

Native Plant Nursery

Forestry operates a 55-acre plant materials nursery at Crow-Hassan Park Reserve, which produces native perennials, trees and shrubs.

All plants grown at the nursery start with seed collected within 25 miles of Hennepin County. The nursery produces approximately 12,500 large bareroot trees and shrubs, 50,000 tree and shrub seedlings, 300 large trees and 2,000 flowering plants annually.

Plant seedlings in a greenhouse
Plants and trees grown in the nursery are planted throughout the park reserves and regional parks. Having the nursery ensures that the Park District has control over the quality and origin of what is planted. 

Tree Disease & Insect Control Program

The tree disease and insect program is designed to monitor and combat problems affecting trees around Three Rivers. Active management of most tree diseases and insects is challenging. All eradication plans are done in accordance with the Three Rivers Park District Pesticide and Fertilizer Use Policy.

The sun shines through tall trees

Current tree disease and insect management projects:

Dutch Elm Disease

Three Rivers Park District does not try to control the overland spread of Dutch Elm via elm bark beetles. However, diseased trees near property within municipalities that have active control programs are removed quickly. Elms in deeper woods are not removed.

Emerald Ash Borer

The first confirmed emerald ash borer (EAB) infestation within Three Rivers Park District was found in February 2018 in Elm Creek Park Reserve. Because the infestation was discovered in an active use area of the park, all of the ash trees in that immediate area must be removed. While it is impossible to determine exactly how EAB was spread to the infested area at Elm Creek Park Reserve, the most likely cause was through unintentional transportation of infested firewood to the picnic area. Learn more about the infestation and management plan.

To delay the spread of EAB, the Park District has instituted a firewood policy that bans visitors from bringing any firewood that is not MDA approved onto any Three Rivers Park District property. The Park District has also developed a response plan with procedures for coping with this insect. The current response plan calls for minimal ash tree management within natural areas, removing roughly 10 percent of ash trees from the Park District annually. All active use areas (e.g. campgrounds, picnic areas) will be monitored and managed to control the impact. The Park District cooperates with the Minnesota Department of Agriculture in their purple trap tree efforts.

Gypsy moth

The Park District actively monitors for gypsy moth population by posting traps in highly susceptible areas. This trapping is coordinated with the Minnesota Department of Agriculture and the USDA Agricultural Plant Health Inspection Service.

Oak Wilt

A close relative of Dutch elm disease, Oak Wilt is a fatal disease that affects all types of oak trees in Minnesota. Three Rivers Park District limits the spread of this disease by cutting the roots around infected trees. A vibratory plow trenching machine is used to cut roots up to five feet underground. After the roots have been cut, any infected and dying trees are cut down and kept sealed under a tarp until they no longer pose a threat to the other oak trees in the forest. The oak wilt control program started in 1976, and over time this program has minimized the number of trees killed. The overall trend shows a decrease in infection centers across the Park District. The two parks in Three Rivers where the majority of oak wilt infections occur are Murphy-Hanrehan Park Reserve in Savage and Hyland Lake Park Reserve in Bloomington. Most of our oak wilt management takes place in forested areas not accessible to the public.

Oak Wilt Infection Centers
District Wide

Year Total Infection Centers
2016 44
2015 43
2014 71
2013 83
2012 56
2011 63
2010 75


There are plenty of ways to volunteer in cooperation with the Three Rivers Department of Natural Resources. Put your time to good use by helping to protect and enrich our earth!