To tend a forest
ESCANABA — Many are the reasons to tend, or manage, a forest. Different forests call for different management systems.
The components of a forest, from the trees to the soil, have been studied for decades. Taking this actively growing body of knowledge and prescribing a set of practices to better grow and protect forests is the art and science of “silviculture”. Nudging ever-changing forests into trajectories that better benefit both humans and forest systems requires thought and wisdom.
Why manage in the first place? A good question, with good answers.
As I explain to elementary school kids, a managed forest produces more “stuff” and helps keep forests healthy. “Stuff” includes timber, habitat, water quality, forest vigor, and many other aspects in the life of a forest and our lifestyles.
In the Lake States, forest characteristics geographically vary in a mosaic of conditions, in as little as a few hundred yards. Sometimes this woodsy tapestry is obvious, such as the gradual transformation from northern hardwoods into swamp conifers. However, much of the time this variability is more subtle, requiring an experienced eye to better see.
This complexity is when forestry gets much more fun. A professional forester can be creative and a forestowner discovers another reason to get excited about their woodland.
So then, “silviculture” is the art and science of controlling the establishment, growth, composition, health, and quality of forests and woodlands to meet the diverse needs and values of forestowners and society on a sustainable basis. Uffda. That’s a mouthful. It’s also the heart of forest management.
In the Lake States, silvicultural practices can be categorized into three broad categories. Each “system” offers plenty of flexibility and hybridization to complement the myriad of forest types.
The most common silviculture in the Lake States is the “selection system”. It involves a successive set of thinnings and improvement cuts, over decades, that steers the forest towards a healthier ecology and higher quality timber. For this system to work, young trees must be fairly tolerant of the shade cast by larger trees.
The amount of light penetrating the forest canopy and reaching the forest floor nurses tree regeneration and optimizes growth and quality of both pole-sized and sawtimber-sized trees. Northern hardwoods, those forests dominated by sugar maple, are the primary target of selection silviculture.
A range of cutting patterns adds choices to selection management. Individual trees can be uniformly harvested, or small groups of trees can be harvested to encourage certain species, or narrow bands can be cleared in progressive “waves” throughout a stand.
One point of caution; be wary of the term “select cut”. Sometimes, this is a misnomer for the degrading practice of “selecting the best and leaving the rest”.
The next most common silvicultural system is clearcutting, which has difficulty with its social license because of the powerful visual change. Clearcutting is purposely designed to mimic natural “catastrophic disturbances” that occur in nature, such as windstorms, wildfire, and massive pest outbreaks. So, the visual change is necessary.
A number of Lake States forest types are adapted to, and dependent upon, these sorts of “disturbances” for regeneration. These tree species tend to be intolerant of shade and need full sunlight in order to grow and mature. Aspen and jack pine forests are poster children for clearcutting silviculture.
A great, fairly recent, active example of this ecological dynamic would be the 2012 Duck Lake fire in the eastern Upper Peninsula. About 22,000 acres of jack pine were burned from a lightning-ignited wildfire. If you drive the sand roads today, you’ll see the mantle of waist-high young jack pine across rolling hills. The transformation and rejuvenation are remarkable.
One reviewer from a stay at the Rainbow Lodge clearly misunderstood the fire effects; “On google maps it looks like they logged it out for miles, disgraceful”. Indeed, the burned-over jack pine had been salvaged for timber, but the driving cause was the wildfire. The salvage harvesting greatly improved the post-fire visual quality.
Rather than waiting for the large and destructive “catastrophic disturbances” of nature, clearcutting strategically regenerates these forest types, piece by piece, without the damage to structures and other human infrastructure. This patchwork landscape embroidery also renders a forest less vulnerable to wildfire, major wind events, and cyclical outbreaks of certain notorious insect pests.
The third broad category of silviculture is shelterwood harvesting. Some look at this as a crossbreed of selection and clearcutting systems, although it’s really in a class of its own.
Shelterwood management consists of two or three harvests over a decade or so. If desired advance regeneration does not exist in the forest understory, the first cut will open the stand to encourage natural regeneration. Exposing mineral soil may be needed for successful regeneration, meaning a winter cut might not work well.
Once seedlings are secured, a second cut, a fairly heavy cut, opens the stand allowing more light which accelerates the growth of the new forest. The remaining canopy nurses the young trees through a bit of cooling shade and typically consists of better quality, windfirm trees. The final cut then removes these mature trees, allowing the sapling-sized trees to freely grow.
High quality oak stands particularly benefit from shelterwood systems.
Silviculture has four general goals in the improvement and protection of forests. A reasonable silvicultural system will meet at least two of the four goals, without compromising other goals.
1. Provide for forest regeneration.
2. Forest products for the good of the owner and society.
3. Improve the quality and health of the forest.
4. Satisfy the desires of the forestowner.
Properly managing a forest embraces a universe of ecological considerations, forestowner goals, and economic environments. Working with a professional forester will help a forestowner navigate through capabilities and expected outcomes of their woodlands. It’s also the best way for a forestowner to learn more about their amazing forest resource. And, that forester may become a best friend of the family.