[5] The necessarily brief statements which are made under this
heading presuppose knowledge of the technical details to which they
refer. In this short history it was possible only to sketch rapidly
the development of the science in terms familiar to the professional
man.
The habit of writing encyclopædic volumes, which the Cameralists and
learned hunters had inaugurated in the preceding century, continued into
the new one, and we find _Hartig_, _Cotta_, _Pfeil_ and _Hundeshagen_
each writing such encyclopædias. _Carl Heyer_ began one in separate
volumes, but completed only two of them. Even an encyclopædic work in
monographs by several authors was undertaken as early as 1819 by _J. M.
Bechstein_, who with his successors brought out fourteen volumes,
covering the ground pretty fully. While in the earlier stages the meager
amount of knowledge made it possible to compress the whole into small
compass, the more modern encyclopædias of _Lorey_, _Fürst_ and
_Dombrowski_ arose from the opposite consideration, namely, the need of
giving a comprehensive survey of the large mass of accumulated
knowledge.
Since 1820, monographic writings, however, became more and more the
practice. Among the volumes which treat certain branches of forestry
monographically, the works of the masters of silviculture, _Cotta_,
_Hartig_ and _Heyer_, based on their experiences in west and middle
Germany, and of _Pfeil_, referring more particularly to North German
conditions, were followed by the South German writers, _Gwinner_ (1834),
and _Stumpf_ (1849). In 1855, _H. Burkhardt_ introduced in his classic
_Säen und Pflanzen_ a new method of treatment, namely, by species, and
after 1850, when the development of general silviculture had been
accomplished, such treatment by species became frequent. Of more modern
works on general silviculture elaborating the attempts at reform of old
practices those of _Gayer_ (1880), _Wagener_ (1884), _Borggreve_ (1885),
_Ney_ (1885), all writing in the same decade, are to be especially
mentioned. In this connection should be also noticed _Fürst’s_ valuable
collective work on nursery practice (_Pflanzenzucht im Walde_, 1882).
At present the magazine literature furnishes ample opportunity to
discuss the development of methods in all directions. The text books at
present appearing seem to be justified by or intended mainly for the
needs of the teacher and rarely for the practitioner. Such a text book
is that by _Weise_. But the latest contributions to silvicultural
literature by _Wagner_ (1907), and _Mayr_ (1909) are works of a new
order, utilizing broader ecological knowledge.
Other branches than silviculture were similarly first treated in
comprehensive volumes and then in monographic writings on special
subjects of the branch. The literature on _forest utilization_ covering
the whole field, was enriched especially by _Pfeil_, _Koenig_, _Gayer_,
and _Fürst_. The first investigation into the physical and technical
properties of wood was conducted by _G. L. Hartig_ himself, followed by
_Theodor Hartig_, and the subject has been most broadly treated by _H.
Noerdlinger_ (1860). In later years, _Schwappach’s_ investigations
deserve special mention.
The question of means of _transportation_ gradually became also a
subject capable of monographic treatment and a series of books came out
on locating and building forest roads. _Braun_ issued such a book in
1855 for the plains country, and _Kaiser_ (1873) for the mountains, also
_Mühlhausen_ (1876), who had been commissioned to locate a perfect road
system over the demonstration forest at the forest academy of Muenden.
Only within the last quarter of the century were railroads introduced
into the economy of forest management. The first comprehensive book on
the subject of logging railroads was issued by _Foerster_ (1885), and a
later one by _Runnebaum_. _Stoetzer_ (1903) furnished in his compact
style the latest discussion on the subject of roads and railroads.
A very comprehensive literature on the value of _forest litter_ was
brought into existence by the established usage of small farmers of
supplying their lack of straw for bedding and manure by substituting the
litter raked from the forest. Hartig and Hundeshagen were active in the
discussion of this subject as well as almost every other forester, the
discussion being, however, mainly based on opinions. But, after 1860,
the subject became so important both to the poor farming population and
to the forest, which was being robbed of its natural fertilizer, that a
more definite basis for regulating its use was established by analysis
and by experiments at the experimental stations.
With the inauguration of the various methods of forest organization
described before, there naturally went hand in hand the development of
_methods of measurement_. Better forest surveys developed rapidly, the
transit generally replacing the compass and plane table. At this period
the necessity for books teaching the important methods of land survey
was met by _Baur_ (1858) and by _Krafft_ (1865). This subject does no
longer occupy a place in forestry literature, the knowledge of it being
taken for granted.
On the other hand the subject of _forest mensuration_ which formerly was
generally treated in connection with forest organization has developed
into a branch by itself, and has been very considerably developed in its
methods and instruments, making a tolerably accurate measurement of
forest growth possible, although many unsolved problems are still under
investigation. Still, late into the century it was customary to measure
only circumferences of trees, by means of a chain or band, although an
instrument for measuring diameters is mentioned by Cotta, in 1804, and
by Hartig, in 1808. _Schœner_ and _Richter_ are in 1813 mentioned as
inventors of the first “universal forest measure” or caliper. The
improvement of calipers to their modern efficiency has been carried on
since 1840 by _Carl_ and _Gustav Heyer_ and by many others until now
self-recording calipers by (_Reuss_, _Wimmenauer_, etc.) have become
practical instruments. For measuring the _heights_ of trees, _Hossfeld_
had already a satisfactory instrument in 1800; a very large number of
improvements in great variety followed, with _Faustmann’s_ mirror
hypsometer probably in the lead. As a special development for measuring
diameters at varying heights _Pressler’s_ instrument should be
mentioned, and a very complicated but extremely accurate one constructed
by _Breymann_.
Various formulas for the computation of the contents of felled trees had
already been developed by _Oettelt_ and others in the eighteenth century
and a formula by _Huber_, using the average area multiplied by length
was definitely introduced in the Prussian practice in 1817. The names of
_Smalian_, _Hossfeld_, _Pressler_ and others are connected with
improvements in these directions.
The idea of _form factors_ and their use was first developed by _Huber_,
who made three tree classes according to the length of crowns, measured
the diameters six feet above ground, and used reduction factors of .75,
.66, .50 for the three classes. But the first formula for determining
form factors is credited to _Hossfeld_ (1812). _Hundeshagen_ and
_Koenig_ also occupied themselves with elaborating form factors.
_Smalian_ (1837) introduced the conception of the _normal_ or true form
factor relating it to the area at one-twentieth of the height. An
entirely new idea has lately been introduced by _Schiffel_, an Austrian
German, under the name of form quotient, placing two measured diameters
in relation.
_Volume tables_ giving the volumes of trees of varying diameters and
height were already in use to some extent in the 18th century; _Cotta_
gives such for beech in 1804, and, in 1817, furnished a new set of
so-called normal tables which were, however, based upon the assumption
of a conical form of the tree. _Koenig_ perfected volume tables by
introducing further classification into five growth classes (1813),
published volume tables for beech and other species, and, in 1840,
published volume tables not for single trees but for entire stands per
acre classified by species, height and density; using the so-called
space number which he had developed in 1835 to denote the density. It is
interesting to note that these tables, which he called _Allgemeine
Waldschætzungstafeln_, were made for the Imperial Russian Society for
the Advancement of Forestry.
In 1840 and succeeding years, the Bavarian government issued a
comprehensive series of measurements and a large number of form factors,
which were used in constructing volume tables; these were found to be so
well made and so generally applicable that they were used in all parts
of Germany and, translated into meter measurement by _Behm_ (1872), are
still generally in use, although new ones based upon further
measurements have been furnished by _Lorey_ and _Kuntze_.
For arriving at the _volume of stands_, estimating was relied upon long
into the nineteenth century, although _Hossfeld_, in 1812, introduced
measuring, and the use of the formula AHF, in which A was the measured
total cross-section area of the stand, H and F the height and form
factors, the latter being at that time still estimated. He first made
form classes for the same heights, but, in 1823, simplified the method
by assuming an average form factor for the whole stand. Even in 1830,
_Kœnig_ still estimated the form factor, although he introduced the
measurement of the cross-section area and determined the height
indirectly as an average of measurements of several height classes, but
_Huber_ (1824) knew how to measure both the average height and form
factor by means of an arithmetic sample tree. This method found entrance
into the practice and held sway until about 1860, when the well-known
improvements by _Draudt_ and _Urich_ supplanted it. These last mentioned
methods have become generally used in the practice, while other methods,
like R. Hartig’s and Pressler’s, have remained mainly theoretical.
The study of the increment and the making of yield tables which had been
inaugurated toward the end of the last century, by _Oettelt_, _Paulsen_,
_Hartig_, and others, was just at the end of that century placed upon a
new basis through _Späth_ (1797), who constructed the first growth
curves by plotting the cubic contents of trees of different ages, and
through _Seutter_ (1799) by introducing stem analysis, on which he based
his yield tables.
On the shoulders of these, _Hossfeld_ (1823) built, when he conceived
the idea of using sample plots for continued observation of the progress
of increment, and he also taught the method of interpolation with
limited measurements, laying the basis for quite elaborate formulæ. But
the first _normal_ yield tables, based on the average trees of an index
stand, were published by _Huber_ (1824) and, in the same year, by
_Hundeshagen_. From that time on, yield tables were constructed by many
others, but only since the Experiment stations undertook to direct their
construction is the hope justified of securing this most invaluable tool
of forest management in reliable and sufficiently detailed form. Even
the newest tables are, however, still deficient, especially in the
direction of detailed information regarding the division into
assortments. The yield tables of _Baur_, _Kuntze_, _Weise_, _Lorey_, and
others are now superseded by those of _Schwappach_ for pine and spruce,
and of _Schuberg_ for fir.
As a result of the many yield tables which gradually accumulated, the
laws of growth in general became more and more cleared up and finally
permitted their formulation as undertaken by _R. Weber_
(_Forsteinrichtung_, 1891).
The idea of using the percentic relations for stating the increment, and
of estimating the future growth upon the basis of past performance for
single trees was known even to _Hartig_ (1795) and _Cotta_ (1804) who
published increment per cent. tables. The methods of making the
measurements of increment on standing trees were especially elaborated
by _Koenig_, _Karl_, _Edward_ and _Gustav Heyer_, _Schneider_ (his
formula, 1853), _Jaeger_, _Borggreve_, and especially by _Pressler_
(1860) who opened new points of view and increased the means of studying
increment by causing the construction of the well-known increment borer,
and in other ways.
The most modern text-book which treats fully of all modern methods of
forest mensuration giving also their history is that of _Udo Müller_
(_Lehrbuch der Holzmesskunde_, 1899), superseding such other good ones,
as those of _Baur_ (1860-1882), _Kuntze_ (1873), _Schwappach_ (short
handbook, last edition 1903).
* * * * *
The many sales of forest property which took place at the beginning of
this period naturally stimulated the elaboration of methods of _forest
valuation_. Even the soil rent theory finds its basis at the very
beginning (1799) in a published letter by two otherwise unknown
foresters (_Bein_ and _Eyber_), who proposed to determine the value of a
forest by discounting the value of the net yield with a limited compound
interest calculation to the 120th year. This idea was elaborated, in
1805, by _Nœrdlinger_ and _Hossfeld_ into the modern conception of
expectancy values, and the now familiar discount calculations were
inaugurated by them. _Cotta_ and _Hartig_ participated also in the
elaboration of methods of forest valuation; Cotta writing his manual in
1804, recognizes the propriety of compound interest calculations, while
Hartig, 1812, still uses only simple interest, and exhibits in his book
as well as in his instructions for practice in the Prussian state
forests rather mixed notions on the subject.
Altogether, even in the earlier part of the period, there arose
considerable difference of opinion and warm discussions, in which all
the prominent foresters took part, as to the use of interest rates and
methods of calculation. But this warfare broke into a red hot flame when
_Faustmann_ (1849) with much mathematical apparatus developed his
formula for the soil expectancy value, and when _Pressler_ and _G.
Heyer_ transferred the discussion into statical fields, making the
question of the financial rotation the issue. Then the advocates of the
soil rent and of the forest rent theories ranged themselves in opposite
camps. This war of opinions, although abated in fervor, still continues,
and the issue is by no means settled.
The discussion of what should be considered the proper felling age or
rotation naturally occupied the minds of foresters from early times; a
maximum volume production being originally the main aim. As early as
1799, _Seutter_ had recognized the fact that the culmination of volume
production had been obtained when the average accretion had culminated.
_Hartig_, in 1808, made the distinction of a physical, an economic and a
mercantilistic, i.e., financial felling age, and _Pfeil_, considerably
ahead of his time, is the first to call (1820) for a rotation based on
maximum soil rent. As, however, he had so often done, he changed his
mind, and while he first advocated even for the state a management for
the highest interest on the soil capital involved, he later rejected
such money management. About the same time _Hundeshagen_ clearly pointed
out the propriety and proper method of basing the rotation on profit
calculations, but it was reserved for a man not a forester to stir up
the modern strife for the proper financial basis, namely _Pressler_, a
professor of mathematics at Tharandt, who became a sharp critic of
existing forest management, and developed to the extreme the net yield
theories.
It was then that the danger of a shortening of the existing rotations,
due to the apparent truth that long rotations were unprofitable, called
for a division into the two camps alluded to; _G. Heyer_, _Judeich_ and
_Lehr_, elaborated especially the mathematical methods of the soil rent
theory, _Krafft_ and _Wagener_ came to the assistance of Pressler, while
_Burkhardt_, _Bose_, _Baur_, _Borggreve_, _Dankelmann_, _Fischbach_ and
others, pleaded for a different policy for the state at least, namely,
the forest rent with the established rotations.
* * * * *
As in the previous period, the mathematical subjects, namely, forest
measurement and forest valuation, were more systematically developed
than the _natural history_ basis of forestry practice; the slower
progress of the latter being caused by the greater difficulties of
studying natural history and of utilizing direct observation.
In _botanical_ direction, descriptive forest botany was first developed,
and several good books were published by _Walther_, _Borkhausen_,
_Bechstein_, _Reum_, the latter (1814), of high value, and also by
_Behlen_, _Gwinner_ and _Hartig_.
In the direction of plant physiology, _Cotta_, early and creditably,
attempted (1806) to explain the movement and function of sap, but
remained unnoticed. _Mayer’s_ (1805-1808) essay on the influence of the
natural forces on the growth and nutrition of trees, contains
interesting physiological explanations for advanced silvicultural
practice. But these sporadic attempts to secure a biological basis were
soon forgotten. Not until _Theodor Hartig_ (1848) published his Anatomy
and Physiology of Woody Plants was the necessity for exact investigation
of forest biology as a basis for silvicultural practice fully
recognized. With the development of general biological botany or
ecology, a new era for silviculture seems to have arrived. Perhaps in
this connection there should be mentioned as one of the earlier
important contributions of much moment, _G. Heyer’s_ _Verhalten der
Bäume gegen Licht und Schatten_ (1856) in which the theory of influence
of light and shade on forest development was elaborated.
Among those who placed the study of pathology of forest trees on a
scientific basis should be mentioned first _Willkomm_ (1876), followed
by _R. Hartig_.
In _zoölogy_, the early writers began with a description of the biology
of game animals. Next, interest in forest insects became natural, and,
in 1818, _Bechstein_ in his Encyclopædia devoted one volume (by
_Scharfenberg_) to the natural history of obnoxious forest insects.
Toward the middle of the century, with the planting of large areas with
single species, insect pests increased, hence the interest in the life
histories of the pests grew and gave rise to the celebrated work by
_Ratzeburg_, “_Die Waldbverderber und Ihre Feinde_” (1841). A number of
similar hand-books on insects and on other zoölogical subjects followed;
the latest, a most complete work on insects, being still based on
Ratzeburg’s work, is that of _Judeich and Nitzsche_, in two volumes
(1895). Of course, the general works on forest protection always
included chapters on forest entomology. The first of these text-books on
forest protection was published by _Laurop_ (1811), and others by
_Bechstein_, _Pfeil_, _Kauschinger_ and recently by _Hess_ (1896), and
_Fürst_ (1889).
* * * * *
_Knowledge of the soil_ was but poorly developed in the encyclopædic
works of the earlier part of the period.
Not till Liebig’s epochmaking investigations was a scientific basis
secured for the subject. Then became possible the improvements in the
contents of such works as _Grebe_ (1886), _Senft_ (1888), and of _Gustav
Heyer_, whose volume (_Lehrbuch der Forstlichen Bodenkunde und
Klimatologie_, 1856), well records the state of knowledge at that time.
But only since then has this field been worked with more scientific
thoroughness by _Ebermayer_, _Schrœder_, _Weber_, _Wollny_, and by
_Ramann_, whose volume on _Bodenkunde_ (1893) may be still considered
the standard of the present day (newest edition, 1910).
The question of the climatic significance of forests is one which first
became recognized as capable of solution by scientific means when the
movement for forest experiment stations began to take shape and the
systematic collecting of observed data was attempted. Most of the
problems are still unsolved.
* * * * *
With the aspects of _political economy_ in reference to forest policy
the foresters had occupied themselves but little, leaving the shaping of
public opinion to the Cameralists, whose influence lasted long into the
century. These produced a good deal of literature in the early years of
the century when the question of retaining or selling state forests was
under discussion, and, under the influence of the teachings of Adam
Smith, their opinion was mostly favorably to sale. Only gradually was
the propriety of state forests recognized by them, till finally the
leading economists, Rau, Roscher and Wagner, took a decided stand in
favor of this view.
The foresters naturally were for retention of the existing State
properties, but one-sided mercantilistic views regarding their
administration persisted with them till modern times.
_Wedekind_, as early as 1821, advocated the theory which is now becoming
a practice, that the state should not only retain, but increase its
present forest property by purchase of all absolute forest soil for the
purpose of reforestation. The erratic and radical Pfeil alone was found
with the Cameralists on the opposite side in 1816, but, by 1834, he had
entirely gone over to the side of the advocates of state forest,
declaring anyone who opposed them fit for the lunatic asylum.
Division of opinions existed also regarding the supervision by the state
of private and communal forests. The political economists were inclined
to reduce, the foresters to increase supervision, excepting again Pfeil
in his earlier writings: he modified his views later by recognizing
supervision as a necessary evil. Cotta, who was inclined to favor free
use of forest property sought to meet the objections to such free use by
increasing the state property.
The main incentive urged by the earlier advocates of state supervision
was the fear of a timber famine. This argument vanished, however, with
the development of railroads, and was then supplanted by the argument of
the protective functions of the forest, a classification into supply
forests and protective forests suggesting differences of treatment.
Nevertheless, the belief that absolute freedom of property rights in the
forest is not in harmony with good political economy--a belief correct
because of the long time element involved--still largely prevails. The
difficulty, however, of supervising private ownership, and the
advantages of state ownership find definite expression in the policy
which Prussia especially is now following, in acquiring gradually the
mismanaged private woodlands and impoverished farm areas for
reforestation, making annual appropriations to this end. Many other
states also are beginning to see the propriety of this movement.
On the whole the systematic study of the economics of forestry has been
rather neglected by foresters, although the subject was discussed by
early writers, _Meyer_, _Laurop_, _Pfeil_, and in modern times by _R.
Weber_, _Lehr_ and _Schwappach_ (“Forstpolitik,” 1894). The latest
comprehensive volume on this subject comes from _Endres_ (1905).