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A Brief History of Forestry.
A Brief History of Forestry.полная версия

Полная версия

A Brief History of Forestry.

Язык: Английский
Год издания: 2017
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The observation that in beech forest the young crop needed protection and succeeded better when gradually freed from the shade of the seed trees, especially on south and west aspects where drought, frost and weeds are apt to injure it on sudden exposure, led to the elaboration of the principle of successive fellings.

In the ordinance of Hanau, as early as 1736, three grades of fellings were developed, the cutting for seed, the cutting for light, which was to begin when the young crop was knee-high, and the removal cutting when the crop was high.

This method spread rapidly and was further developed by the addition (in 1767) of a preparatory cutting, to secure a desirable seedbed, and by lengthening the period of regeneration and elaborating other detail, so that, by 1790, the principles of natural regeneration under nursetrees for beech forest were fully developed in Western Germany.

In other parts, hardwood forest management was but little developed. The Prussian Forest Ordinance of 1786 contented itself with forbidding the selection method, by declaring natural regeneration, as practiced in the pineries, not applicable; while the Austrian Ordinance of 1786 recognizes only clearing followed by planting as the general rule.

b. Artificial Reforestation. Although sporadic attempts at sowing and planting are on record as early as the beginning of the 14th century, extensive artificial reforestation did not begin until the middle of the 18th century, by which time planting methods were quite fully developed.

Among the hardwoods, the oak was the first to receive special attention. By the middle of the 16th century the forest ordinances gave quite explicit instructions for planting oak in the so-called Hutewald, a combination of pasture and tree growth such as is found to-day in the bluegrass region of Kentucky; the remnants of these poor pasture woods with their gnarly oaks have lasted into modern times.

In the forest ordinance of Brunswick (1598) orders are given to plant on felling areas: “every full farmer shall every year at the proper time set out ten young oaks, every half farmer five, every farm laborer three, well taken up with roots (wildlings), and plant them in the commons or openings at Martini (November) or Mitfasten (Easter) and cover them with thorn brush” (to protect them against cattle).

About that time it was, indeed, incumbent on every marker to sow annually five oaks, or plant several young seedlings for every tree cut and to tend them a few years; and the custom existed in the low country, – afterwards (1700) introduced by law in Saxony – to plant in celebration of certain occurrences – a kind of arborday– especially to celebrate the marriage day; in order to be married the bridegroom had to prove that he had planted a certain number of oaks, which in Prussia (1719) had to be six, besides six fruit trees. The existence of this custom, now long forgotten, has given rise in the United States to the story that this is the method by which the German forest is maintained.

The method of collecting and keeping acorns over winter was well known in 1579, as is evidenced by the Hohenlohe Forest Ordinance, which advised fall sowing, but, if that did not prove successful, to prepare the ground in summer, leave it through the winter and sow in the spring.

While, in earlier times, sowing seems to have had the preference, at a later period planting was practiced, at first with wildlings, but as early as 1603 we find mention of oak nurseries.

The Prussian Order of 1720 ordered the foresters to plant oaks in the openings before Christmas, for which they were to be paid, if the trees were found alive after three years. The growing and culture of oak also interested Frederick the Great, who ordered its extension everywhere. Very explicit and correct rules for growing and transplanting them, and some to which we would not subscribe, were given in the books of the 18th century. Among the planting methods we find, in 1719 and again in 1776, one similar to the Manteuffel method of planting in mounds.

While oak culture was especially fostered in Northwestern Germany, the cultivation of conifers first received attention in the southwest, and in the same manner which was inaugurated by the Nuremberg seed dealer in 1368. A new idea, introduced in the Palatine Forest Ordinance (1565) and in the Bavarian Forest Ordinance (1568), was the prescription, to soak the seed before use and sow mixed with sawdust or sand, bringing the seed under with brush or iron rakes.

Carlowitz (1713) taught well the methods of collecting, extracting and keeping the seed, and even proposed seed tests. The seedbeds were to be made as for carrots, dense sowings to be thinned, and the thinnings transplanted into nursery rows, the seedbeds to be covered with moss and litter to protect them against heaving; he also discusses the question of cost. The adaptation of plant material to different sites – conifers where oaks are not suitable – was also understood (Bavarian Forest Ordinance, 1683).

As long as the old method of extracting the seed in hot stoves or ovens prevailed, conifer sowings gave but indifferent results.

In the pine forests of Prussia, during the second half of the 18th century, the method of sowing the cones on large waste and sand barrens, where the sun would make them release the seed, was practised, and before Brémontier had written his celebrated mémoire sur les dunes, sanddunes had been recovered with pine plantations in Germany in the manner which is still in vogue.

The planting of conifers came into practice much later, and then it was mostly done with wildlings. Opinions differing as to the value of sowing or planting, it was erroneously held until the 19th century that planting was less successful and too costly in comparison with the small harvest yield, which necessitated cheapness of operations. It was only towards the end of the 18th century that planting of pine was resorted to, but merely for repairing fail places in sowings and natural regeneration, and then with a ball of earth (1779), using a hollow spade, – a costly method. The cost of a certain plantation made in 1751 is, however, reported as less than $3.00 per M., in 1770 as low as 70 cents per M. To cheapen the operations the labor was exchanged for wood, pasture or other materials or advantages.

In Prussia, in 1773, all recipients of free wood had to do service in the cultures; in 1785, every farmer had to furnish a certain amount of cones or acorns. The method, lately adopted in Russia, came into vogue in Prussia in 1719, namely, of charging, besides the value of the wood, a toll to be paid into the planting fund (about 7 % of the value). This method was also imitated elsewhere.

The use of the Waldfeldbau (combined farm and forest culture) was also inaugurated for the purpose of cheapening the cost of plantations (by v. Langen in 1744) when the great movement for reforesting wastes and openings began, the tree seed being sown with the grain either at once or after farm use for some years.

Regular annual planting budgets (of $50 – $100 – $200) were inaugurated in Brunswick by v. Langen in 1745; and in 1781, the Prussian forest administration had attained to entirely modern planting plans and annual planting budgets.

It was no wonder that the fear of a timber famine and the apparent hopelessness of bringing improvement into the existing forest conditions created anxiety and a desire to plant rapid growers, such as birch, willow, aspen, alder; the planting of the White Birch became so general in the beginning of the 18th century that a regular betulomania is recorded corresponding to the incipient catalpomania in the United States.

At that time, to be sure, firewood was still the main concern, and the use of these rapid growing species had some justification. But where birch was mixed in spruce plantations its baneful effects consisting in whipping off the spruce tips and injuring its neighbors were soon recognized, and much trouble was experienced in getting rid of the unwelcome addition.

The Robinia, which had been brought from America in 1638, was also one of the trees recommended in the middle of the 18th century and was much planted until Hartig pointed out that the expectations from it were entirely misplaced.

Of course no building material could be expected from these species, hence the larch, also a rapid grower, was transplanted from the Alps (1730 in Harz mountains), and its use was extended, as with us, to conditions for which it was not adapted.

It was principally a desire for novelty and perhaps for better, especially foreign things, that led to the planting of North American species in parks during the first half of the 18th century. But, although F. A. J. von Wangenheim’s very competent writings on the American forest-flora and on the laws of naturalization (1787) stimulated interest in that direction, the use of American species for forest planting was not inaugurated till nearly 100 years later, with the single exception of the White Pine (P. strobus), of which large numbers were planted.

7. Improvement of the Crop

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.

8. Methods of Regulating Forest Management

Organized forest management was slower to develop than silvicultural methods. The first attempts to bring order into the progress of fellings took the form of dividing the whole area into a certain number of felling areas (12, 16, 20, 30, etc.), several ordinances dating from the middle of the 15th and 17th centuries containing prescriptions to that effect.

It is doubtful whether the numbers of these areas indicate years of rotation, in which case they could only have applied to coppice, or whether they indicate periods of return in selection forest, although the historians seem to jump to the former conclusion. The area division practiced by v. Langen in the Harz mountains (1745), who prescribed the division of larger districts into fifty to sixty, of smaller districts into twenty to thirty felling areas, also leaves it doubtful, whether the areas corresponded to an assumed rotation or to a period of return.

At first, the division was not into equal areas, for no survey existed, and its object was simply to localize the cutting and provide orderly progress. The subdivision was made in the mountain country by following the topography, valleys and ridges, while in the plain the lines opened up for purposes of the chase (to set up nets), called Schneisen or Gestelle (rides), bounding square areas called Jagen, Quadrat, Stallung, were used for the limitation of the felling areas. Most commonly, however, largely due to absence of surveys, the ordered division did not materialize, but existed only on paper.

With more exact measuring of areas, and with the conception of a rotation or longer periods of return, it was recognized that the inequality of the sites or soil qualities, especially in mountain districts, produced very unequal felling budgets. To overcome this inequality, Jacobi, in Goettingen (1741) introduced proportional felling areas, making the felling areas on poor sites permanently larger.

Similarly, v. Langen and Zanthier attempt to secure equal annual returns without slavishly holding to the geometric division, merely making sure that the total area be cut over in the predetermined rotation.

The first attempts to introduce a regulated management by making a volume division the basis is recorded from the Harz mountains in 1547. This method, based on very crude estimates although upon very fair forest description, was continued into the 18th century.

In the last half of the 18th century all these crude methods were improved, and applied on extensive areas.

In 1785, Zanthier combined area and volume division, determining the felling budget on each felling area by counting and estimating the trees and calculating how many trees could be used annually under a sustained yield management; the area division being used only as a check or means of control.

A very considerable advance was made by Oettelt, (who surveyed and regulated the Weimar forests in 1760) in the elaboration of details and establishment of proper principles for regulating the felling budget.

In his forest description he introduces for the first time periodic age classes, usually six, but of uneven length: Young growth, below twelve years; thicket, twelve to twenty-four years; polewood, twenty-four to forty years; clear timber, forty to fifty; medium timber, fifty to seventy-five; mature timber, seventy-five years and over.

He divides the forest into proportional areas (which were marked by stones in the woods), equalizing them according to age, quality, increment, soil, exposure, so as to secure equal annual budgets; the stands were ranged into seven or eight unequal age classes and each into as many annual felling areas as there are years in the age class; if some of the age classes were absent, he extended the time for cutting in the older class until the younger had grown to the proper age and by varying the cut from good to poor sites for stands he tried to even out the budgets. The volume budget he determined by average increment measurements. This method was, however, much too far advanced and required too much mathematics to find imitators at that time.

Another method which proved also too complex for the foresters of the time was that of v. Wedell; nevertheless, by 1790, he had by it put into working order 800,000 acres in Silesia. He divided this area into districts, the districts into blocks or management classes, and used an elaborated proportional area division for determining the felling budget. He distinguished quality of stand and quality of site, and made four site classes. The volume of stock, he found by means of sample areas, to which he added the increment in order to find the total volume for harvest, when it could be determined how long with a given budget the stands would last, or what average annual felling budget could be taken before the next age-class would be mature.

In the North German plain, with very uniform conditions of soil and timber, the method of equal felling areas was the most natural and most easily applied.

Frederick the Great, who took a considerable interest in forestry matters, ordered such an area division for the State pineries in 1740, fixing upon different numbers of felling areas, but finally, in 1770, deciding on a rotation of seventy years. Lack of personnel retarded progress in this forest survey and regulation until in 1778 v. Kropff undertook the direction. Not agreeing with his master regarding the short rotation of seventy years, he arranged to have each district divided into two working blocks, and by cutting alternately in these, managed to double that rotation. His successor, Hennert, in 1788, devised a new method by introducing allotment of a number of annual felling areas to a period of the rotation when at least the periodic budget could be equalized. A value or money yield equalization of the felling budgets was also attempted.

For easier handling, the forest was divided into small compartments or Jagen and a classification of four, still uneven, periodic age classes (of different length for conifers and broadleaved forest), and three site qualities were employed. The merchantable stock was ascertained by a sample area method and the felling budget by dividing the oldest age class by the number of years it must last until the next was ready. Since no attempt was made to secure a proper age class gradation, the method failed to improve conditions for the next rotation.

Some 500,000 acres were regulated according to this plan in Prussia, probably very superficially.

In 1789, Bavaria also ordered a division into annual felling areas.

In all these methods of regulating the yield or budget, the area played the main role, the volume being only a secondary consideration.

The first elaboration of a pure volume division was made by Beckman in 1759. He estimated stock on hand by trees and guessed more or less at the increment, allowing 2.5, 2, and 1 % for the different sites, and then made a year to year calculation of stock for 125 years. How the felling budget was finally determined is not known.

Two methods were simultaneously devised in Württemberg in 1783, which form the transition to the so-called allotment methods, making periodic age classes of an equal number of years and allotting either felling areas or volumes to each period of the rotation. Incapacity of the officials prevented the application of the one method, while the other, devised by Maurer, remained also only a proposition.

But, in 1788, Kregting in his Mathematical Contributions to Forestry Science teaches a pure volume allotment method with ten year age classes and nearly all the apparatus which was afterward developed by Hartig, who in the next period dominated to such a large extent the development of forestry in all its branches.

9. Improvements in Methods of Mensuration

In scientific direction, the mathematical disciplines were the first to be developed; the natural sciences received attention much later.

A considerable amount of mathematical knowledge was required for this work of forest organization. The mathematical apparatus of the foresters even at the end of this period was rather slender, but its development went hand in hand with the development of these methods of regulation; and even elaborate mathematical formulæ for determining felling budgets were not absent.

Until nearly the middle of the 18th century, surveys of exact nature were almost unknown; only when the division into equal or proportionate felling areas became the basis for determining the felling budgets, did the necessity for such surveys present itself.

Plane table and compass were the instruments which came into use in the beginning of the 18th century. But not until the latter half of that century were extensive forest surveys and maps of various character made, especially in Prussia under Wedell, Kropff and Hennert.

The methods of measurement of wood developed still later. Until Oettelt’s time no method of precise determination of volumes was known, everything being estimated by cords or by diameter breast-high and height, or by the number of boards which a tree would make (board feet?).

The diameter was sometimes used as a price maker, the price increasing in direct proportion to the diameter increase. Oettelt calculated the volume of coniferous trees as cones, and Vierenklee, who wrote a book on mathematics for the use of foresters, calculated timbers with the top removed by using the average diameter, to which Hennert added the volume of a cone with the difference of the two diameters as a base, to make the total tree volume.

Most measurements of standing trees were, of course, made on the circumference, for, in the absence of calipers, the diameter could be directly measured only on the felled tree. Doebel had already measured the height by means of a rectangular triangle, and the first real hypsometer with movable sights was described by Jung in 1781; and a complete instrument, which could be used for measuring both height and diameter at any height, similar to some more modern ones, was constructed by Reinhold.

Determination of the real wood contents in a cord of wood and of the volume of bark by measurement was taught by Oettelt, and the method of immersion in water and measuring the displaced volume, by Hennert (1782).

In 1785, Krohne first called attention to the variation of the increment in different age classes and the need of determining the accretion for each separately.

In 1789, Trunk taught how to determine average felling age increment, and also the method of determining the change of diameter classes, which is now used by the United States Forest Service: “On good soil a tree grows one inch in three years, on medium soil in four years, on poor soil in five years.” With this knowledge, the attainment of a given diameter, or the change from one diameter or age class to the next could be calculated.

Volume tables were at Trunk’s command, and Paulsen in 1787, Kregting in 1788, mention periodic yield tables; but generally speaking “ocular taxation” or estimating was the rule, checked by experience in actual fellings, the method of the American timber looker. Generally, of course, only the log timber was estimated as with us, and only the very roughest estimating or rather guessing was in vogue until near the end of the period.

The first attempt at closer measurement was made by Beckman (1756), who surrounded the area to be measured with twine, drove a colored wooden peg into each tree, one color for each diameter class, when, knowing the original number of pegs that had been taken out, the difference gave the number of trees in each diameter class, and by multiplying the average cubic contents of a measured sample tree in each class by the number in the class its volume was found.

The method, often employed at present, of ascertaining by tally the diameter classes on strips forty to fifty paces wide, the so-called strip survey, was described by Zanthier in 1763.

These measurements were usually confined to sample areas, the use of such being already known in 1739. The contents of the sample area, if a special degree of accuracy was desired, were ascertained by felling the whole and measuring.

Oettelt, of mathematical fame, was the first to publish something about the determination of the age of trees by counting rings, although the practice probably antedates this account. He knew of the dependence of the ring width on the site and on the density of the stand.

It seems that long before this time the French had made the determination of yield in a more scientific manner, Réaumur reporting in 1721 to the French Academy comparative studies of the yield of coppice and of volumes of wood.

Oettelt, too, laid the foundation of forest financial calculations when he ascertained the value of a forest by determining the value of an acre of mature wood – the oldest age class – and multiplying it by half the acreage of the whole forest, suggesting the well known expression for the normal stock soon after to be developed by an obscure Austrian tax collector.

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