As stated before, to Hartig and Cotta belongs the credit of having
applied systematically on a large scale methods of forest organization
for sustained yield; Hartig having been active in Prussia since 1811,
and Cotta beginning to organize the Saxon forests in the same year. The
method employed by Hartig, the so-called volume allotment, had been
already formulated and its foundation laid by Kregting and others
(although Hartig seems to have claimed the invention). But it was
reserved to Hartig to build up this method in its detail, and to
formulate clearly and precisely its application, as well as to improve
the practice of forest survey, calculation of increment, and the making
of yield tables. His method involved a survey, a subdivision, a
construction of yield tables and the formulation of working plans, in
which the principle according to which the forest was to be managed
during the whole rotation was laid down for each district. The rotation
was determined, divided into periods, finally of twenty years, and the
periodic volume yield represented by all stands was distributed through
all the periods of the rotation in such a manner as to make the periodic
felling budgets approximately equal; or, since the tendency to increased
wood consumption was recognized, an increase of the felling budget
toward the end of the rotation was considered desirable.
Cotta based his system of forest organization upon a method described by
a Bavarian, Schilcher (1796); it relied primarily upon area rather than
volume division. This method was later on (1817), called by him
_Flaechenfachwerk_ (area allotment). It divides the rotation into
periods and allots areas for each periodic felling budget. But before
this time, in 1804, Cotta had himself formulated a method of his own,
which combined the area and volume method, the volume being the main
basis and the area being merely used as a check. While Hartig
dogmatically and persistently carried out his difficult scheme, Cotta
was open-minded enough to improve his method of regulation, and by 1820,
in his _Anweisung zur Forst-Einrichtung und -Abschaetzung_, he comes to
his final position of basing the sustained yield entirely on the area
allotment, using the estimate of volume simply to secure an
approximately uniform felling budget. He laid particular stress on
orderly procedure in the subdivision and progress of the fellings. He
did not prepare an elaborate working plan binding for the entire
rotation, but merely prescribed the principles of the general
management, and, after 1816, he confined the formulating of felling and
planting plans only to the next decade.
A similar method, making a closer combination of volume and area
allotment, now known as the combined allotment, in which the area forms
the main basis for distributing the felling budgets, was prescribed by
Klipstein in 1833. This, also, confines the working plan to the first
period of the rotation and for this period alone makes a rather careful
statement of the expected volume budget; a new budget is then to be
determined at the beginning of the next period. This idea of confining
the budget determination to a comparatively short period is now
generally accepted, the future receiving only summary consideration.
These methods of organization were the ones generally applied in
practice, and are still with some modifications in practical use. About
1820, however, new theories were advanced which led to the formulation
of methods based upon the idea of the _normal forest_. The conception of
a normal forest, with a normal stock, distributed in normal age classes,
so as to insure a sustained yield management, was evolved, in 1788, by
an obscure anonymous official in the Tax-collector’s office of Austria,
designed for assessing woods managed for sustained yield. This fertile
idea, which is still the basis of forest organization in Austria, and
explains better than any other method the principles involved in forest
organization, did not find entrance into forestry literature in all its
detail until 1811 when André compared this so-called _Cameraltaxe_ with
Hartig’s method of regulation. We find, however, that, simultaneously
with the Austrian invention of this method, Paulsen (1787) proposed to
determine the felling budget as a relation between normal stock and
normal yield, and in his yield tables (the first of the kind, 1795), he
gives the proportion of increment to normal stock in percentic relation,
so that the felling budget may be either expressed as a fraction of the
stock or as a per cent.; in beech forests, for instance, he determines
the felling budget as 3.3% on best sites, 2.5% on medium, and 1.8% on
poor sites.
Probably stimulated by André’s description, _Huber_ (1812) developed a
method and formula which may be considered the foundation of the later
development by Carl Heyer (Felling budget = I + ((Sa - Sn)/e)).
Based upon the normal forest idea, a number of methods were elaborated
which, because of their employing a mathematical formula for the
determination of the felling budget, are known as _formula methods_;
they are, indeed modified rational volume divisions.
Hundeshagen has the merit of having first clearly explained the basis of
these methods, and himself developed a formula, of the correctness of
which he was so convinced as to designate his method as “the rational”
one. Two other formulæ were brought into the world by Koenig
(1838-1851), but the credit of the most complete elaboration both of the
principles of the normal forest idea and of its practical application
belongs to Carl Heyer. The principles of his method are briefly: First
determine upon the period of regulation during which the abnormal forest
is to be brought nearer to normal conditions; the length of this period
to be determined with due regard to the financial requirements or
ability of the owner and to the conditions of the forest. The actual
stock on hand is then determined and the total increment, based on the
average increment at felling age of each stand, which will take place
during this period, is added. Deducting from this total what has been
calculated as the proper normal stock requisite for a sustained yield
management, the balance is available for felling budgets which may be
utilized in annual or periodic instalments during the period of
regulation. A working plan is provided which takes care of securing an
orderly progress of fellings and proper location of age classes, to be
revised every ten years.
Although this is undoubtedly the most rational method yet devised, it
has remained largely unused, and is found in somewhat modified
application only in Austria and Baden.
An entirely new principle in the theory of forest organization was
introduced, when the aim of forest management was formulated to be the
highest soil rent. According to this requirement the proper harvest time
of any stand, or even of any tree, was to be determined by the so-called
index per cent., that is, a calculation which determines whether a stand
or a tree is still producing at a proper predetermined rate, or is
declining. The advocates of this principle were especially _Pressler_
(professor of mathematics at Tharandt, 1840 to 1843) and _G. Heyer_, son
of Carl Heyer, who based his method on his father’s formula, merely
introducing values for volumes. _Judeich_, director of the Tharandt
school, also developed in the sixties a method, based upon financial
theory, which is to attain the highest rate per cent. on the capital
invested in forest production. On the basis of survey and subdivision of
working blocks composing a felling series, and with a rotation
determined by financial calculations with interest accounts, he makes a
periodic area division for determining the felling budget in general,
and in addition employs the index per cent., as explained, for
determining in each allotted stand the more exact time for its harvest.
While these men pleaded for a strict finance calculation, such as is
properly applied to any business making financial results the main
issue, the defenders of the old regime, which sought the object of
forest management mainly in highest material or value production,
advanced as their financial program the attainment of the highest forest
rent as opposed to the highest soil rent. They neglected and derided the
complicated interest calculations which have to take into consideration
uncertain future developments, and were satisfied with producing a
satisfactory balance, a surplus of income over expenses, no matter what
interest rate on the capital involved in soil and forest growth that
might represent.
At the present time these financial propositions are still mainly under
heated discussion.
In actual practice, the various state forest administrations, with the
exception of the Saxon one, continue to rely upon the older methods in
regulating the management of their forest properties without reference
to financial theories. This is largely due to momentum of the practical
existence and application of these methods in earlier times and the
difficulty and impracticability of a change. Just now, however, several
of the State administrations are preparing to radically revise their
working plans.
In Prussia, the instructions for working plans of 1819 formulated by
Hartig were improved upon by his successor, Oberlandforstmeister _von
Reuss_ (1836), and these instructions formed the basis of the work of
forest regulation until the end of the 19th century. It is a periodic
area allotment with only a summary check by volume. The working plan is
only to secure a rational location and gradation of age classes; the
calculations of yields and specific rules of management are lately
confined to the first period and are revised every six years.
In Saxony, Cotta’s area method was systematically developed, and, as the
larger part of Saxon forests is coniferous, mainly spruce, the proper
location of age classes forms a special consideration for the progress
of fellings. The determination of volume and increment was left to
summary estimates, and the area division became entirely superior. The
original idea of Cotta that orderly procedure in the management is of
more importance than the actual determination and equalization of yield
still pervades the Saxon practice. Since 1860, an attempt has been made
to calculate the rotation and determine the felling budget on the
principle of the soil rent, at least as a corrective of the annual
budget, and in general to lean towards Judeich’s stand management.
In Bavaria, after various changes, a complete allotment method of area
and volume had come into vogue, in 1819; but, at the present writing
(1911) an entirely new and modern re-organization has been begun, in
which most modern ideas and especially much freedom of movement, even to
deviation from the principle of sustained yield, is allowed.
In Württemberg, where, in 1818 to 1822, a pure volume allotment had been
introduced, in 1862 to 1863 the combined allotment method was begun, the
felling budget being determined in a general way for the next two or
three periods, and more precisely for the first decade, without
attempting more than approximate equality.
In 1898, new instructions were issued, which abandon the allotment
method and restrict the yield regulation to designating felling areas
for the first period.
In Baden, where the forest organization began in 1836 upon the basis of
volume allotment, a change was made in 1849 to an area allotment,
simplifying to a greater extent than anywhere else the calculation of
the yield; finally, Heyer’s method was adopted entirely in 1869.
It appears then that the schematic allotment methods found the most
general application in the earlier time of the period, being favored
probably on account of their simplicity in application. The improvement
in their present application over the original methods as designed by
Hartig and Cotta, is that now they require no volume calculation for any
long future, but are satisfied with making a sufficiently accurate
calculation and provision for the proper felling budget for the present.