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Ecological Landscapes of Wisconsin

Wisconsin forests are incredibly diverse in species composition and structure, mainly due to glaciation that occurred until 11,500 years ago across much of the state. Glaciation in Wisconsin reached its maximum extent nearly 21,000 years ago.

To help guide management decisions and considerations, Wisconsin is divided into 16 ecological landscapes defined by the vegetation, climate, geology and hydrology in each ecological unit. Information about each ecological landscape is available on the DNR website in the landscapes topic.

Ecological Landscapes of Wisconsin. Credit: Wisconsin DNR

The Forestry Bubble

The middle-aged bubble does not only pertain to the baby boomer generation. Wisconsin forests are experiencing this age phenomenon as well.  Wisconsin forest data shows a significant bubble of acreage in the middle age class (60-80 years old) with lesser amounts in the very young and very old age classes. This middle age bubble can be attributed in part to the cutover period when many of these forests originated.

Total acreage of timberland between 1983 and 2017 distributed by stand age class. Error bars represent the 68% confidence interval. Source: Forest Inventory and Analysis, 2017.

Monitoring The Condition Of Wisconsin’s Forest Regeneration

Have you ever wondered how Wisconsin’s forests are monitored for regeneration? Forest regeneration, the process of renewing tree cover by establishing young trees, is one of the most basic and important elements of sustainable forest management. After a harvest or disturbance event, like a fire or heavy winds, successful regeneration is crucial to developing healthy, productive forests that can provide sustainable economic and ecological functions. Forest regrowth patterns must be well understood to manage Wisconsin’s forest resources sustainably.

In 2018, the DNR’s Forestry Division launched the Forest Regeneration Monitoring (FRM) program to better assess the status and progression of naturally regenerating forests on county, state, federal and private lands across the state.

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A New Way To Measure Tree Equity

By Dan Buckler, DNR Urban Forest Assessment Specialist, Madison, daniel.buckler@wisconsin.gov or 608-445-4578

One needs only to look outside their window or at an aerial image to see that trees are not distributed evenly in their community. Of course, this is often expected and not indicative of any significant problem. One would expect, for example, for many parks to have more trees than densely developed parts of town.

However, sometimes uneven canopy distribution reveals something more harmful – that some neighborhoods and communities, often more wealthy ones, enjoy more canopy cover and thus more of the benefits trees provide. To help identify and mitigate this issue, American Forests recently released Tree Equity Score.

Figure 1 – an example of Tree Equity Score used in Oshkosh, WI. See the score along with demographic and environmental information on the left column.

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Oriental Bittersweet: A Bitter Beauty!

Article By: Jaqi Christopher, Invasive plant specialist & Mary Bartkowiak, Invasive plant coordinator

Just as the leaves begin to shift from summer green to the fall shades of gold, orange, red and bronze, the fruits of Oriental bittersweet explode on the scene with their very own show-stopping colors of bright gold and red.

The sight of these vines full of colorful berries may tempt the casual observer to take these berry-filled branches home to use as fall decorations or to plant in their own garden. This, however, would be a mistake, as this striking plant is a serious threat to native ecosystems. Oriental bittersweet is a restricted species under Wisconsin’s Invasive Species Rule NR40. This makes it illegal to transport, transfer or introduce Oriental bittersweet statewide.

Oriental bittersweet is an aggressive-growing woody vine that invades forests, woodlands, fields and hedgerows. The vines twine up trees, smother the crown and girdle trunks with their thick woody stems. In fact, the sheer weight of the vine can cause tree crowns to break and collapse and whole trees to uproot. Additionally, large mats of bittersweet can shade out native plants.

Oriental bittersweet woody vine twines up tree, girdling tree trunk

Oriental bittersweet vine girdles tree trunks. Photo Credit: Minnesota Department of Agriculture

Oriental bittersweet woody vine twines up tree, girdling tree trunk

Oriental bittersweet vine girdles tree trunks. Photo Credit: University of Illinois’ Chris Evans














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Snow Fleas Come To The Surface

By Todd Lanigan, Forest Health Specialist, Eau Claire. Todd.Lanigan@wisconsin.gov or 715-210-0150

Snow fleas are a species of springtails that are active during the winter and are generally found in groups where their dark-colored bodies stand out against the white snow. While often observed in late winter or early spring, they also come to the surface on warm winter days. Cold weather drives snow fleas back below the surface to wait for better weather. 

Many snow fleas on snow.

Easily mistaken for specks of dirt or debris, snow fleas are tiny soil-dwelling animals that gather on the surface of the snow on warm winter and spring days.

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Feature species: Turkish filbert

T. Davis Sydnor, The Ohio State University, Bugwood.org

Scientific Name: Corylus colurna

Native to: southeast Europe and western Asia

Mature Height*: 40-55’

Spread*: 20-30’

Form: conical, symmetrical, medium texture

Growth Rate*: medium (35 feet over a 20-year period)

Foliage: 3-5”, dense green, simple leaf

Fall Color: poor, yellowish-green

Flowers: inconspicuous; catkins in early spring can be rather handsome

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Cold hardiness zone maps: how many versions are there, and how are they different?

By Dan Buckler, DNR urban forest assessment specialist, Madison, daniel.buckler@wisconsin.gov, 608-445-4578

Jack Frost descends upon us all in Wisconsin, but the depths to which he brings the mercury differ depending on your latitude, elevation, and proximity to water or urban areas. These differences are observed in a location’s cold hardiness zone, which represents the average minimum temperature a location is expected to experience.

Cold hardiness zones are well-known decision-making factors for anybody with a smidge of green on their thumb. But did you know that there are multiple hardiness zone maps out there, and that where you stand right now might be in zone 6 on one map, but zone 5 on another? Enter the labyrinth, dear reader.

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