Treesearch

It takes little scanning of "Timber Trends in the United States" (U.S. Forest Service 1965) to realize that the hardwood timber of our country needs a great deal of improvement. About 27 percent of the total growing stock of the Nation is hardwoods, 90 percent of the hardwoods are eastern species, and most of them are of poor quality.

Several environmental factors necessary for tree growth undergo rhythmic and sometimes abrupt changes during the course of a year, and even during a day. Since wood cells are susceptible to outside influences during their differentiation, certain fluctuations of environmental conditions invariably leave a permanent imprint on xylem anatomy, and hence significantly influence wood quality. Such features as the width of annual increments, cell length, cell diameter, cell wall thickness, and the development of drought and frost rings are affected by environmental factors to some degree. The...

In 1959 and 1960, during a series of symposia on wood quality organized jointly by the Ontario Department of Lands and Forests, the Faculty of Forestry of the University of Toronto, and the Ontario Research Foundation (ORF), it became clear that there was a serious lack of information regarding the structure and variability of the wood of the commercially important species of Ontario. Following these symposia a Wood Quality Unit was set up within the Department of Lands and Forests' Research Branch, and at about the same time the Department undertook to sponsor a wood quality research...

Investigations of mineral nutrient-tree growth relationships have dealt mainly with associations involving foliage composition, root formation, or volume production of wood. Few studies have been concerned with changes in wood anatomy associated with element deficiency. In 1949 Davis reported that calcium deficiency was accompanied by a reduction of primary tissue and an increase in secondary tissue in loblolly pine (Pinus taeda L.) stems. Murphey et al. (1962) found that nutrient defiencies affected the percentage of phloem formed and reduced both vessel diameter and the number of rays in...

As the tree improvement and genetic programs supply better planting stock, a more suitable environment must be provided if their full potential is to be realized. This will require much more information than we now have on how nutrient deficiencies affect the growth and anatomy of forest trees. The importance of anatomical studies has been shown by Church (1949) and Harper (1913). They found that one of the first effects of defoliation is a marked reduction in latewood formation. Furthermore, the assumption that anatomical features exert an influence on the physical and mechanical propertie...

Yellow birch (Betula alleghaniensis Britt.) is an important hardwood species in the Lake States, northeastern United States, and eastern Canada. Since it produces valuable timber, the species is a logical candidate for genetic improvement. An understanding of the variation pattern in a species is, however, basic to any improvement program. In 1963 the Institute of Forest Genetics, Rhinelander, Wisconsin, initiated a study of natural variation in yellow birch. This paper describes variation in height growth and growth cessation in 2-year-old seedlings grown from the material collected for...

The external appearance of the bark of sugar maple (Acer saccharum Marsh.) has been described as "deeply furrowed," "fissured with long irregular thick plates or ridges," "somewhat scaly," "sometimes curling," and "highly variable." Adjacent trees in natural stands often have strikingly different external bark characteristics. Gross variability in bark appearance is unusual within a species. In general, bark appearance is relatively constant, and any variability encountered is often a reflection of vigor. Indeed, some researchers consider external bark characteristics to be helpful in log...