Crop Tree Management
Due to the fact that trees grow slowly compared to humans, a number of management activities have been established to assist landowners in achieving their forestry objectives as quickly as possible. One of these activities is crop tree management.
The basic premise of crop tree management is to select individual trees that will meet the landowners objectives and encourage these individuals to grow. By releasing these individual trees from competition, their growth and vigor is increased. Vigorous trees are less susceptible to disease, will produce greater mast, and will increase their volume at a substantially faster rate than less vigorous trees.
In the past, crop tree management was used primarily in the context of timber production. However, as landowner objective trends have hanged over time to other values such as wildlife habitat and aesthetics, the crop tree management activity has adapted and can be used to enhance these other values as well.
Black Cherry Crop Tree Candidate
In the northeast, area wide thinning is a popular method of harvesting timber and improving a woodlot. This course of action is appropriate and beneficial. However, most foresters incorporate a modified form of crop tree management when planning an area wide thinning. While a thinning will concentrate on removing the poor and unhealthy trees, most foresters will also make marking decisions based on releasing some of the better quality individuals. Crop tree management differs from thinning primarily in the level of intensity.
Crop tree management requires the forester to focus his/her attention on retaining those specific trees with the greatest potential to produce the benefits desired by the landowner. The forester is required to single out and release those crop trees, which will often require the removal of some trees that would not normally be removed in a thinning.
In relation to timber production, quality is the primary consideration as opposed to quantity. The quality of the tree is the single most important factor in determining its value. In the northeast, there is an abundant supply of low quality trees, hence their low value. High quality trees on the other hand are limited and is reflected in the extremely high prices paid for high quality logs.
The first step in the crop tree management process is for the landowner to determine his/her property goals. Once the overall property goals are established, objectives can be determined for the individual stands. Because objectives will vary from stand to stand, the appropriate silvicultural prescription will also vary. Not all stands are suitable for crop tree management, and the ones that are may have limitations.
Once stand objectives are determined, it is then appropriate to establish the selection criteria for the individual crop trees. For example, if the production of high quality hardwood sawlogs is the primary objective in a stand, a list of criteria would possibly include:
The tree species must be a high value species.
The tree must have a healthy crown.
The tree must not have V-shaped connections.
The species is appropriate for the site.
The butt-log has the potential of grade 1 or better.
The butt-log has no epicormic branching.
The premise of determining the crop tree criteria holds true for establishing crop trees for wildlife habitat and aesthetics as well. Some of the individual criteria will differ based on the landowners' objectives, but the basic idea is to only release those trees which show the greatest potential to meet the objectives. In many instances a timber crop tree is also suitable as a wildlife crop tree.
The next step is to determine how many crop trees are to be released. First, an inventory of the property is taken to estimate the number of crop trees available. Next, the landowner and forester decide how many of those available trees will be released. This number is usually based on a trees per acre basis. The more crop trees selected for release, the heavier the cutting will be.
When making the decision on the number of trees to release, the landowner must keep in mind the level of risk. Having a high number of crop trees per acre essentially requires the landowner to put "all of his/her eggs in one basket". Because a number of trees will be removed which would not normally be removed with a traditional thinning, the opportunity to salvage the stand after a significant wind storm or other natural disaster, will be less than after a traditional thinning. This risk makes the crop tree management option sound less appealing, but taking into account the potential high rate of return of a successful crop tree release can make it more palatable. Think of it as making a decision on the type of stock to invest in. There is the relatively low risk medium return stock option (traditional thinning) versus the higher risk greater return option (crop tree management).
If you look at the difference in growth and return between a traditional thinning versus crop tree management, the crop tree management should, at the very least, be considered. I do not necessarily advocate crop tree management on an entire parcel, but on an individual stand basis, it is appropriate. Land managers should equate this to investing your money in a mutual fund containing some high risk stocks, medium risk stocks, and low risk stocks - rather than investing al of your money in just one stock. Selecting stands for traditional thinning and stands to be managed using the crop tree method diversifies your portfolio.
I am a strong advocate of the crop tree management process and have practiced this technique on some of my own land. Unfortunately I am not in the position to report on the results as it has only occurred in the past year. With vigilance and a little luck, 15 years from now I will be writing my last newsletter article about the success of crop tree management, and my early retirement provided by the tremendous return on the investment I made those 15 years ago!
- Tony Lamberton
Manchester Center Manager