Treesearch

One of the major objectives of the tree-improvement program of the Central States Forest Experiment Station of the U.S. Forest Service is to select and breed hardwood trees that are inherently capable of producing wood of high quality. To begin this program we must select from natural stands and plantations the best possible parent trees. In recent years we have developed a method for identifying white oak trees (Quercus alba L.) that have the highest probability of being inherently superior stock for producing high-quality logs.

The Lake States Forest Experiment Station has given active support to the Lake States Forest Tree Improvement Committee since the Committee's inception in 1953. In the interests of encouraging and coordinating forest genetics activities in this region, we are happy to publish this Proceedings of the Fifth Lake States Forest Tree Improvement Conference, as we did for the preceding four conferences.

The white-pine weevil, Pissodes strobi, is a particularly insidious forest pest that can render a stand of host trees virtually worthless. It rarely, if ever, kills a tree; but the crooks, forks, and internal defects that develop in attacked trees over a period of years may reduce the merchantable volume and value of the tree at harvest age to zero. Dollar losses are especially high in plantations where costs of planting and care have been incurred.

Polyhedral viruses have proved highly effective and very practical for control of certain pine sawflies; and a method of collecting and processing the small polyhedra (5 microns or less) characteristic of sawflies has been described. There is experimental evidence that the virus diseases of many Lepidopterous insects can be used similarly for direct control. The polyhedra of most caterpillars, such as the gypsy moth and forest tent caterpillar, are larger (6 t o 15 microns) and the method of processing them for control use is somewhat simpler. The preparation of polyhedral material from...

In the mound-and-depression microtopography of the northern hardwood forest, leaves are blown off the mounds and collect in the depressions. This influence of microtopography on leaf accumulation is responsible for much of the variation in humus depth; and this, in turn, affects the formation and depth of soil frost.

Rhododendron (Rhododendron maximum L.) is a large shrub that presents problems in timber management throughout the Appalachian Mountains. Although sometimes found in single clumps, rhododendron characteristically occurs in extensive dense thickets reaching heights of 10 feet or more (fig. 1). Of major concern to foresters is the difficulty in securing tree regeneration on areas occupied by this shrub. Also, because of its prolific growth, rhododendron undoubtedly competes severely with existing overstory trees for moisture and nutrients. Except where aesthetic values are a consideration,...