Treesearch

The list of wildlife species known to prefer paper birch and yellow birch as food ls a long one. To mention a few: beavers and porcupines chew on the bark and wood; sapsuckers feed on the sap; other songbirds—notably the redpoll, pine siskin, and chikadee—relish the seeds; ruffed grouse eat the catkins, buds, and seeds (in northern Maine and Canada this bird is often called the "birch partridge"); and snowshoe hare, moose, and whitetail deer browse on the twigs. At least 24 different kinds of animals are known to feed on birches.

Yellow birch and paper birch are similar in that both are light-demanding throughout most of their life and require freedom from competition to produce high-value products. However, the two species differ markedly in other silvical characteristics. Yellow birch seldom constitutes a large proportion of the stand: it grows slowly and is long-lived. In contrast, paper birch sometimes makes up a high proportion of the stand: it has rapid early growth, and tends to be short-lived (Cooley 1962, Powells 1965). Both birches are responsive to intermediate cuttings and other cultural practices that...

Before timber managers invest their time and money in precommercial thinnings in paper birch stands, they should know what thinning options are open to them and should have some idea of the response they might expect from the alternatives. Equipped with a knowledge of these options, the manager can select the monetary and output goals that best suit his own situation in managing paper birch stands. A study of three precommercial thinning practices by our timber-management research division in a paper birch stand provided the necessary physical data for making an economic evaluation of some...

One objective in forestry is to earn the greatest possible return on the capital invested in growing timber. To do this, the forester not only must know which silvicultural methods to use, but also ought to know the methods of economic analysis that will help him make the decisions that will lead to the greatest return. The financial maturity concept provides a method of economic analysis by which the forester can evaluate the business aspects of timber growing. This concept is based on the rates of value increase that can be expected of trees over a given period of time.

The methods used to compute financial maturity of yellow birch sawtimber are similar to those used for paper birch sawtimber, except for minor differences in detail. The procedure followed for yellow-birch veneer-log trees was also similar, except that local veneer grades and local veneer-log prices were used as the basis for the financial maturity computations.

Paper birch and yellow birch are not attacked by pathogens that cause widespread killing. Most of their diseases are associated with accidents and negligence. The major problems are discoloration and decay associated with wounds on low-vigor trees. Many of these problems could be alleviated through better management. And better management depends on better understanding of the problem. The purpose of this paper is to outline briefly the major diseases of birch.

Native birches are subject to attack by insects at all stages of growth from the germinating seedling to the mature tree. All parts of the tree—roots, stem, branches, foliage, and even the developing seed—may be utilized as feeding sites by insects of one kind or another. An enumeration of the many insects recorded in the literature as feeders on birch might be impressive in numbers but would contribute little to this symposium. Rather, it would seem more appropriate to consider a few representative kinds of insects that are responsible for particular types of injury, to indicate...

Much of the slow growth and low quality of our birches and other northern hardwoods in New England can be traced to inadequate soil fertility. This problem can be overcome by remedial fertilization, which will enhance the production of healthy, vigorous birch trees.

Intensive forest management depends heavily upon our ability to measure, control, and predict the growth, yield, or general development of timber stands, regardless of whether the management goal is for timber, aesthetics, recreation, water, or wildlife. A large amount of mensurational data about birch stands has been developed in recent years or synthesized from available information (Marquis et al. 1969, Leak et al. 1969). This information, which is summarized in this paper, covers site estimation, stocking, short-term growth, and yield. The information about paper birch applies to...

Little interest has been shown in genetic improvement of our native birches until fairly recently, except for the birch breeding and testing begun by the Northeastern Forest Experiment Station in 1940. Before we can begin improvement of a particular species or genus, we need to know how much genetic variation is present and how various characteristics are inherited. Most of the work with birch at the Institute of Forest Genetics at Rhinelander has sought to provide this kind of information. We will report first on the knowledge of birch genetics acquired so far and relate it to practical...