We hear the term, "selective cut" used all the time in Maine. People will say, "I had a selective cut done on my woodlot", or the logger will tell the landowner that he will perform a selective cut during the timber harvest. Sounds good but it is not always what is best for the forest stand or may be a misrepresentation of what is expected. It may also result in poor results.
Selective harvesting does have a place in forest management. It means more than choosing the largest trees and harvesting them. That is usually referred to as "high-grading". If you remove all of the big trees and leave the smaller ones, you may not get the results you were hoping for. I have seen this many times. I have seen some nice plantations selectively cut that resulted in removing the nice trees and leaving the suppressed and poor quality trees. In cases like this, you might as well clearcut the plantation and start over. The suppressed trees have poor tops, are weak, and may not recover very well. The same applies to woodlots in many cases. Selective cuts can set back forests for decades if done improperly.
Selective harvesting is usually associated with uneven-age management of the forest. You will end up with different size classes and tree heights in the forest. This can be part of a good strategy that can benefit the forest and add the diversity that wildlife like.
Selective harvesting applies to forest types that have the capability of regenerating under their own shade. In northern Maine, this refers to northern hardwoods that are composed of sugar maple, beech, and yellow birch. It also refers to softwood species such as balsam fir, spruce, hemlock, and cedar. White pine is not as shade tolerant as the above mentioned species but is included in this list with limitations. The stand objective must be to have trees of various sizes and ages. The trees selected for the harvest will leave the residual stand in better condition than before the harvest. “Better” has to do with tree health, tree quality, growing space, species mix, stand density, and other factors.
No two stands are the same in the forest. Each stand must be assessed and then a prescription can be given to the kind of harvest that is necessary. A combination of cuts may be prescribed. Single tree selection is often used with maple. This will leave small holes in the forest canopy and leave a more uniform distribution of trees. Group selection leaves larger patches and can favor a greater diversity of tree species that require more light, such as white birch, aspen, white pine, and hemlock. Hemlock is shade tolerant but requires more light to be released and start growing better.
Selection harvesting is a very complex forest management system. Selecting trees to harvest requires knowledge of forest ecology, a discerning eye, and plenty of experience. Professional foresters have this knowledge and sometimes will mark the trees to be harvested. Sometimes, a forester will work with a logging contractor with sufficient knowledge and the logger can choose the trees to be harvested. Some loggers have this knowledge and can do it themselves, but you need to have the right logger.
The selection system is only one way to harvest timber and you have to choose the right system based on stand conditions and other factors. Factors such as current forest conditions, forest types, and landowner objectives all come into play when making decisions about the forest harvest. Having a vision of what you want your stand to look like in the future is very important. You have to work with what you have and nature.