Читать книгу A Brief History of Forestry - B. E. Fernow - Страница 23

Thinning of stands had been practiced early in the 16th century, not for improvement of the remaining stand so much as to secure fence material, although in 1531 the observation was already recorded that thinning improved and stimulated the remaining growth.

In the 17th century, opposite views, or, at least doubts as to its usefulness were expressed in the forest orders, and sometimes thinning was even forbidden. Even in the 18th century some of the prominent foresters, Doebel and Beckman, were opposed to it, and although others favored the operation, the practice of it remained limited.

In 1761, we find the first good statement of the theory of thinnings by Berlepsch, who advised taking out the suppressed trees when the sound poles were clear of lower and middle branches; he also accentuated the financial argument of earlier returns and increased value of the remainder.

About the same time, Zanthier recommended two thinnings, namely, for conifers first in the thirtieth to fortieth year and again in the fiftieth year, for broadleaf forest first in the forty-fifth and again in the eightieth to ninetieth year.

In 1765, the financial gain from thinnings is figured by Oettelt, and the possible reduction of the rotation due to thinnings is recognized by Leubert in 1774.

Just as the thinning in polewoods arose from the need of earlier utilization, so the weeding of young growths was done for the purpose of getting material for withes to bind the grain, etc.

The removal of coppice shoots in oak plantings was practiced in Prussia in 1719, and the thinning of too dense sowings was advised by Carlowitz in 1713. Yet much later, even such an intelligent man as Oettelt inveighed against the weeding out of the birch in spruce sowings because “nature prefers variety, with which preference it is not good to interfere.”

This was in opposition to v. Langen (1745), who prescribed for the first time regular cleaning or weeding, especially the removal of the softwoods, aspen and birch, and of coppice shoots from seedling forest. It was also known that this weeding is best done “in the full sap,” in order to kill the stocks.