Crop-tree Management

Crop-tree management is a technique that focuses on “individual” trees that have the potential to develop into high-value crop trees. Perkey and others (1993) emphasize that crop-tree value should be defined by the landowners objectives. The two phases in crop-tree management are assessment and enhancement. Generally the assessment phase involves the selection of trees that have the potential for meeting the objectives defined by the landowner. Enhancement consists of activities that foster the attainment of those objectives. For example, if timber management was the objective, trees of desirable species with good stem quality and capable of responding to release would be selected as crop trees. The enhancement operation would release crop trees by removing some of the trees that compete with them for sunlight, water, and nutrients. The recommended method for releasing crop trees is the "crown-touching" method described by Lamson and others (1988). To apply this method, the crop-tree crown is divided into four quadrants (sides) and one determines whether the tree is free-to-grow on each of these sides. A three-sided release has been recommended by Lamson and others (1990) for use in younger stands. For older stands or for species with a tendency toward epicormic branching, a two-sided release is more appropriate. Cutting, girdling, or the use of herbicides (Miller 1984) can accomplish release of the crop tree. The advantages of crop-tree management are:

1. It permits crop-tree designation to fit landowner objectives
2. It is simple to apply and fits well with NIPF needs
3. It provides for an even flow of forest products over time
4. It allows for continuous forest cover until crop trees are harvested
5. Management efforts are concentrated on trees with the highest potential for future gain

Crop-tree management has disadvantages:

1. It does not provide for regeneration after removal of crop trees
2. Sometimes removal of low-grade interfering trees may not be a commercial operation and thus may constitute a cost to the landowner

However generally speaking, crop-tree management like improvement cutting is a widely applicable method that is appropriate to many mixed hardwood stands. The earlier the crop-tree enhancement can be applied to a stand, the longer the effect can benefit the crop trees. However, there are risks in attempting to assess crop trees and potential competitors at early ages.