Treesearch

Foresters generally recognize that diameter growth, height growth, sprouting vigor, and seed production are partially related to age; so age often has an important bearing upon silvicultural decisions. But unless past stand histories are fully known, the ages of hardwood trees can be determined only by increment borings, which not only require excessive time but also expose the trees to stain and decay. As an alternative, many foresters assume that for silvicultural purposes tree diameter at breast height is accurate enough as a guide to tree age. For managed even-aged stands, this...

In the Appalachian Mountains, the logging operator usually cuts only those trees that he thinks will yield a profit, and leaves the trees that appear to be unprofitable. Generally these unprofitable trees are either below merchantable size or are culls-trees of merchantable size that contain too little sound material to justify harvesting costs.

Two-thirds of the annual runoff from watersheds in the Allegheny Plateau of central New York comes from the snow-or snow and rain that falls in December through April. Although the amounts of precipitation in this period are fairly uniform from year to year, the proportion that falls as snow varies; so does the amount that accumulates on the ground, and its duration and rate of melt. The differences in ground cover also affect snow deposition and melt and the timing and amount of runoff from this snow.

Green ash (Fraxinus pennsylvanica Marsh.) is one of the few native hardwood species that has been planted for afforestation in appreciable numbers in this country. In the Central States this species has been grown mainly on submarginal farmland and on strip-mine spoil banks, while in the Great Plains it has been planted for shelterbelts. In the Northeast, only limited experimental plantings have been attempted.

Marking trees for felling or deadening was one of the important operations when an economic study of forest-management costs and returns was begun in 1959 on a 600-acre management unit of the U. S. Forest Service's Fernow Experimental Forest near Parsons, W. Va. This is a report on the cost of marking for the initial cutting operation.

Tip moths1 cause conspicuous damage to loblolly pine reproduction in eastern Maryland, especially on old-field sites. As the number of old-field plantations and the value of forest crops have increased, landowners and managers have become interested in the possibility of controlling this damage and perhaps improving the form and growth of their planted trees.

The egg masses of some lepidopterous insects are covered by a mat of hairs that for some research purposes must be removed. Doing this by hand is tedious. Besides, the hairs on the egg masses of certain insects such as the gypsy moth (Porthetria dispar [L.] and the browntail moth Nygmia phaeorrhoea [Donov.]) can cause severe allergic reactions in persons who are exposed to them.

Because variation in sex ratio is an important factor in the population dynamics of the gypsy moth (Porthetria dispar), it is necessary to have some means of determining the ratio of males to females in a population at the beginning of the larval period as well as in the later stages. For determining the sex of fully developed embryos and early-instar larvae, a simple whole-mount microscope technique has been devised.

Each winter gives examples of the insulating properties of snow cover. Seeds and soil fauna are protected from the cold by snow. Underground water pipes are less likely to freeze under snow cover. And, according to many observers, the occurrence, penetration, and thaw of soil frost are affected by snow cover. The depth of snow necessary to protect soil from freezing will depend, of course, on the air temperature.

In managing hardwood stands, one of the most important tasks is to secure adequate reproduction of desirable species after harvest cuttings. Natural reproduction is usually relied upon. This can be either advance growth (seedlings or seedling sprouts) or reproduction that becomes established after the cutting. Which one the forest manager should mainly rely upon depends on several factors: relative tolerance of desired and undesired species, abundance of desirable stems and their competitors, logging damage, and cost of different methods of tilting succession to favor preferred species.