Reforestation is the renewal of a forest after a disturbance. This can be through natural processes or as a result of forest management. Contrary to popular belief, deforestation – or long term loss of forest cover – isn’t generally the result of fire or logging but because of land conversion to agriculture and urbanization. In the U.S. there is currently 747 million acres of forest or 33% of the total land area [AF&PA, 1997] – more forest land than a century ago.
Different types of harvest methods are available to serve different types of management goals. Looking broadly at the long-term goals of each particular stand, foresters select a method of harvesting that will serve a reforestation goal. In the US reforestation methods are broken down into even-aged stands and uneven aged stands. Even-aged reforestation involves removal of the mature overstory of trees, allowing a new crop of trees to be established. Uneven-aged systems maintain and regenerate stands with many age classes, generally composed of mature trees, pole-sized younger trees, and seedlings.
Methods suited to tree species that tolerate shade during the early stages of development. Managing and regenerating forests in an uneven-aged condition requires removal of some trees of all sizes either singularly or in small groups. Two selection harvest systems used to remove merchantable trees, create openings for regeneration, and to release saplings and pole-sized trees are group selection and single tree selection.
Group Selection – Trees are removed in small group openings. The maximum width of a group opening may be up to twice the height of the mature trees. Small openings provide sites suitable for some species of fir, spruce, maple, red cedar and hemlock that can regenerate in partial shade. Larger openings that allow more light to reach the forest floor are generally used to regenerate species requiring more light such as Douglas-fir, oaks, yellow birch, and loblolly pine. With Group Selection, groups are not managed as separate stands. Regeneration, growth, and yield are managed over the entire forest tract.
Single Tree Selection
In Single Tree Selection, individual trees of all size classes are removed more or less uniformly throughout the entire stand. Very small openings in the overstory allow a limited amount of sunlight to reach the forest floor. Generally, this system allows regeneration of only the most shade-tolerant species like hemlock, beech and sugar maple. Single tree selection is also used on very dry and frost prone sites in some regions of the U.S. to regenerate species like ponderosa pine.
Some species of trees are shade-intolerant – species which will not tolerate shade during the early stages of development. In order for these species to grow they require open clearings with no overstory competition. In nature, these pioneer species typically are established after a major disturbance, like a fire, creates an opening for them. Several reforestation systems and harvesting methods can be used to create even-aged stands. While specific treatments vary across the U.S. by tree species and climate, the basic systems are seed tree, shelterwood, and clearcutting.
Seed Tree – This even-aged reforestation method uses mature trees (usually 6 to 15 per acre) from the existing stand to provide seed for regenerating a new stand of trees. Seed trees are typically removed after regeneration is established, but can be retained for wildlife or aesthetics objectives. The primary objective of a seed tree regeneration harvest is to provide a natural seed source. Planting is sometimes used to supplement natural seeding. White pine, the southern pines and several species of oak may be regenerated using the seed tree harvesting method.
Shelterwood – In this method, even-aged stands regenerate beneath the shade provided by mature trees from the previous stand. A typical sequence of treatments can include three distinct types of cuttings: 1) an optional preparatory cut that enhances conditions for seed production; 2) an establishment cut that also prepares the seed bed and provides seed for the new stand; and 3) a removal cut that releases established seedlings and saplings from competition with the overstory. Cutting may be done to leave seed-producing trees uniformly throughout the stand, in groups, or strips. As with seed tree harvests, shelterwoods are sometimes planted to supplement natural seeding. Red and white oak, the southern pines, white pine, and sugar maple are examples of tree species that may be regenerated using the shelterwood harvesting method.
Clearcutting is the removal, in a single cutting, of all overstory trees in a stand to develop a new stand in a shade free environment; reforestation occurs by natural seeding, direct seeding, planting, or sprouting. Harvest cutting may be done in groups or patches, or in strips. Each individual clearcut area is a unit in which regeneration, growth, and yield are managed. Within clearcuts, certain trees or groups of trees may be left for wildlife, and buffer strips are maintained to protect streams, wetlands, and special areas. Planting or direct seeding are the most commonly used methods of reforestation when using clearcuts, but clearcuts can be designed to regenerate by natural seeding. The use of genetically improved seedlings—for increased growth and resistance to diseases and insects—can greatly improve the financial returns of your investment in reforestation. Common tree species regenerated using clearcutting include the southern pines, Douglas-fir, red and white oak, jack pine, white birch, aspen, and yellow-poplar.
Few topics are as controversial as clearcutting which involves removing all the trees on a parcel of land. The primary goal of clearcutting is to create the conditions needed to re-establish even-aged stands of valuable shade-intolerant hardwood and softwood species. Fresh clearcuts are not aesthetically pleasing and often conjure up images of desolation and destruction. However, most clearcuts are rapidly colonized by pioneer plants including a wide variety of shrubs and herbs. Trees are planted or come back through natural regeneration. Foresters view clearcuts as the beginning of reforestation. Forest land converted for agricultural use or for development is deforestation. There is no way around this fact of life.
In the past, some large clearcuts have been necessary to salvage dead and dying timber from infestations such as the spruce budworm. However, there have also been some large and irresponsible liquidation clearcuts for short term gain. Now numerous regulations are in place which limit the size of clearcuts and ensure that all forest practices are sustainable. Trees are left in stream side buffers to protect water quality and fish habitat. Clearcuts are designed to blend in with the landscape and uncut buffer zones are left along highways. Aesthetics is now recognized as a basic human value. Clearcutting is a sound silvicultural practice when done responsibly.
Most companies in the forest products industry
now subscribe to the “Sustainable Forestry Initiative”
which goes beyond forest practices mandated by state and federal laws.
Nature has been clearcutting timber stands for millenniums with wind throw, insect and disease infestations, and fire. This has been important in creating a mosaic of stands which create structural, and consequently, biological diversity across a landscape. The silvicultural practice of clearcutting allows us to duplicate natural events without losing precious wood fiber. Removing a foresters ability to use small clearcuts would ensure that shade tolerant species would eventually replace valuable shade intolerant species like Douglas Fir.
The public is often presented with black and white options such as choosing between selective cutting and clearcutting. Clearcutting is usually presented as all bad and selective cutting as all good. One of the worst forest practices was high grading or taking only the best trees. This was actually a form of selective cutting.
Life in the forest isn’t black and white. Foresters manage dynamic forests to reproduce “desired outcomes” again and again, over decades and centuries. They must take into consideration the fact that everything is connected and everything is constantly changing. They need all available tools at their disposal to work with the discordant harmonies of nature.
There is no excuse for practices of the past where thousands of contiguous acres were clearcut across streams and down steep mountainsides causing erosion, stream sedimentation and soil degradation. The public is still angry and needs to know that these practices are a thing of the past.
An informed public understands that responsible clearcuts in the forest come back with beautiful reproduction, but many of our cities, housing developments, malls, and highways were carved from forests by clearcutting and converting the land to another use. This is deforestation. Virtually all forest loss in North America is due to development, not forest practices. Population and per capita consumption create the demand for all resources, including land for agriculture and development.
If forest owners are forced to stop using silvicultural tools, like clearcutting in certain stands, forestry may become uneconomical. Forest owners may then exercise the right to sell their land to developers for conversion to other uses, all of which have a much greater environmental impact. This makes the most intensive forestry looks environmentally benign. There are no simple solutions…only intelligent choices. Responsible clearcutting is a tool which must stay in the foresters kit.
Finally, it is always important to have a historical perspective. We have a great example in Maine which is now 90% forested, the most heavily forested state in the nation. However 30% of Maine was once cleared for agriculture. They didn’t build stone walls in the woods, but there are plenty of stone walls in the woods today. There was massive deforestation in Maine and other states, converting forest land to agricultural use to feed the growing population. As better agricultural lands were found to the West much of New England reverted to forest.
In the United States, we have converted over 310,000,000 acres of forest land to agricultural use to produce food. Ironically, there is no outrage when viewing farms, but often extreme outrage when viewing a fresh clearcut in the forest. Perhaps we should consider a forest clearcut as a temporary meadow that will support deer and other forage browsers on its way back to a lush forest stand. Aesthetics is important, but we all see and feel different things based on our knowledge and experience.
Click here to read “Weyerhaeuser In Action – Clearcutting” from their website.
Weyerhaeuser is a large forest products company.