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Wisconsin Natural Resources magazine

Wisconsin Natural Resources magazine

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Pockets of old-growth forests may be found in the Great Lakes states in areas that were not logged, or that were very lightly logged. © JMAR Foto-Werks

October 2004

Old growth

A rare treasure.

Karl Martin, Natasha Kassulke and Tony Rinaldi

Pockets of old-growth forests may be found in the Great Lakes states in areas that were not logged, or that were very lightly logged.

© JMAR Foto-Werks

Maintaining and restoring a legacy

Hiking an old-growth area can be an awe-inspiring experience. In the Sylvania Wilderness Area of Michigan, ancient trees such as massive yellow birch, hemlock and maple stretch skyward humbling hikers with their grandeur and antiquity. Hikers' heads tilt back searching the canopy for the topmost branches, often in vain.


Old-growth forests have been called America's original forests.

Old-growth forests mean different things to different people. But in simple terms, old-growth consists of old trees where there has been little o no human intervention. These are sometimes called virgin forests or "first forests."

To early settlers and lumberjacks these forests were seen as a barrier to progress and a valuable natural resource to be exploited. Today, although not completely understood, they are valued for their scientific, aesthetic, ethical and recreational qualities.

"Old-growth forest represents a unique ecosystem that was once abundant across the forested regions of Wisconsin but is now very rare," says Signe Holtz, bureau director for DNR's endangered resources program. "As stewards of the land it is important for us and our generation to try to maintain and restore this habitat type on Wisconsin's landscape for future generations."

Surveys conclude that only about one percent of Wisconsin's old-growth forests remain in tact. According to a 1995 study by the U.S. Department of Interior's National Biological Service, less than five percent of the lower 48 states' original old growth forests remain and most of this is concentrated on publicly owned lands in the Pacific Northwest.

In the Pacific Northwest, the first thing you notice about the remaining old-growth forests is the sheer tree size. Large conifers that range from 250 years to well over 1,000-years-old with heights of 100 feet to 370 feet and diameters of six or more feet dominate these forests. These are diverse forests – a mixture of old and young trees, mosses, insects, plants and animals including the northern spotted owl, marten and black bear.

Many southern Wisconsin forests were cleared for agriculture by the late 1800s, while forests in the north were heavily cut for timber by the early 1900s. Therefore, almost all the mature trees you see today are second-growth forest or younger, regrown after land clearing and settlement. Most of these trees are less than 125 years old.

The challenge is to not only preserve the small pockets where old-growth remains, but to develop more old-growth and learn how to mimic nature to develop old-growth characteristics while producing wood products for society's needs.

"It may be possible to accelerate development of old-growth characteristics development through harvesting that mimics natural processes," says Karl Martin, a forest research ecologist in Rhinelander. "By making various-sized openings in the canopy, leaving some areas uncut and increasing the amount of dead standing and downed wood, we should be able to increase species diversity, age structure, forest structure and accelerate the development of large trees in these stands. These are key components of an old-growth forest."

Maintaining and restoring a legacy

Some people just want old-growth to exist even if they never get a chance to see it, Martin says. This desire is a focus of several environmental organizations across the country. But this interest has to be tempered with society's growing wood and paper product consumption.

Scientists view old-growth as an opportunity to investigate the interworkings of a complex ecosystem and to maintain biodiversity and natural processes. Not only old-growth forests, but forests in general, are valuable for many reasons. They keep soil from eroding, help to keep water clean, hold nutrients important for plant growth in place and provide animal habitat.

"Many people agree that there should be old-growth forests, but often times they cannot agree on how much and where," Martin says.

Across the country and in Wisconsin, there are areas purposely unmanaged or passively managed (no active treatment of vegetation) where old-growth either exists or is developing.

Located near Woodruff in Oneida County, the Kemp Natural Resources Station's 135 acres support remnants of old-growth forests. This environment supports a diverse population of mammals, birds, amphibians, reptiles, fish and invertebrates.

The management emphasis on areas where old-growth exists or is developing is usually for recreation or research rather than pulp or timber. Such areas have different designations including wilderness, natural areas, research areas, wildlife refuges and parks. Even within these areas there is sometimes pressure to harvest wood, especially for salvage purposes following wildfire, windstorms or insect outbreaks.

Despite conflicting interests over public land use, segments of society want to designate more old-growth areas as non-commercial. Increasingly, consumer markets are moving away from old-growth wood. Some major corporations have pledged to end the use of old-growth wood in manufacturing their products and product packaging.

In Wisconsin, managing these forests involves controlling and removing exotic species, designing management plans for lands around and between old-growth forests, and monitoring changes in the forest.

Natasha Kassulke is the associate editor of Wisconsin Natural Resources magazine.