_Natural regeneration_ continued to be the favorite method well into
this period, and, for a long time, selection forest and coppice were all
that was known in practice until Hartig and Cotta forced recognition of
the shelterwood system.
The only way in which a transition from the generally practiced,
unregulated selection forest to an intensive management was possible,
with the ignorant personnel of underforesters, was to formulate into an
easily intelligible prescription the necessary rules, allowing the least
play to individual judgment. This was done by Hartig when he formulated
his eight “General Rules” (1808) which coincided also closely with the
teachings of Cotta. Since these rules represent in brief and most
definitely the status of silvicultural knowledge on natural regeneration
at the time, it may be desirable to translate them _verbatim_.
(1) “Every forest tree which is expected to propagate itself by natural
regeneration must be old enough to bear good seed.
(2) “Every district or stand which is to be replaced by a thoroughly
perfect stand by means of natural regeneration, must be brought into
such position (density) that the soil may everywhere receive sufficient
seeding.
(3) “Each compartment must be kept in such condition (density) that it
cannot, before the seeding takes place, grow up to grass and weeds.
(4) “With species whose seed loses its power of germination through
frost, as is the case with the oak and beech, the compartments must be
given such a position (density) that the foliage which after the fall of
seed covers and protects the same cannot be carried away by wind.
(5) “All stands must be given such density that the germinating plants
in the same, as long as they are still tender, find sufficient
protection from their mother trees against heat of the sun and against
cold.
(6) “So soon as the young stand resulting from natural regeneration does
not any longer require this motherly protection, it must gradually,
through the careful removal of the mother trees, be accustomed to the
weather, and finally must be entirely brought into the open position.
(7) “All the young growths, whether secured by natural or artificial
seeding, must be freed from the accompanying less useful species and
from weeds, if these in spite of all precaution threaten the better
kinds.
(8) “From every young forest until it is full grown, the suppressed wood
must be removed from time to time, so that the trees which are ahead or
dominate may grow the better; the upper perfect crown cover, however,
must not be interrupted until it is the intention to grow a new forest
again in the place of the old one.”
Since these rules are applicable only in beech forests, much mischief
and misconception resulted from their generalization; pure, even-aged
high forests became the ideal, and the mixed forest, which was
originally the most widespread condition, vanished to a large extent.
This was especially unfortunate in Northern and Northeastern pine
forests.
A reaction against Hartig’s generalization began about 1830, under the
lead of Pfeil. He had at first agreed with Hartig, and then with equal
narrowness advocated for many years a clear cutting system with
artificial reforestation. Finally, however, he was not afraid to
acknowledge that his early generalizations in this respect were a
mistake, and that different conditions required different treatment.
In the development of the shelterwood system there was at first, under
the lead of Hartig, a tendency to open up rather sharply, taking out
about three-fourths of the existing stand, but gradually he became
convinced that this was too much, and finally reduced the first removal
to only about one-third of the stand. This was the origin of his
nickname of _Dunkelman_. In spite of the fact that it was claimed that
Cotta took the opposite view (for which he was called _Lichtman_), he,
too, grew to favor a dark position, and, as he progressed, leaned more
and more towards more careful opening up. Hartig originally recognized
only three different fellings: the cutting for seed; the cutting for
light; and the removal cutting. By and by, a second cut was made during
the seed year, and the number of fellings to secure gradual removal were
increased, so that, by 1801, this system seems to have been pretty
nearly perfected to its modern conditions. The best exposition of this
_Femelschlagbetrieb_ (shelterwood system), as then developed, is to be
found in Karl Heyer’s Handbook, 1854.
The method was unfortunately extended by Burgsdorf (1787) to the
Northern pineries with a seventy year period of rotation. Within ten
years, however, he recognized its inappropriateness, and modified it by
instructions to leave only six to twelve seed trees per acre. His
successor, Kropff, reduced the number of seed trees to four or five,
which were to be removed within two or three years. In spite of the
development of this more rational method, the practitioners under
Hartig’s approval, held mainly to a dark position even for pine, much in
the manner of a selection forest, which produced a poor growth of
oppressed seedlings, retarding for a long time the development of the
pineries.
In spruce or fir, either a pure selection forest or a strip system was
employed. Attempts at a shelterwood system were made, but experience
with the wind danger soon taught the lesson that this was not a proper
method with shallow-rooted species. Even Hartig preferred for spruce
clearing and planting, and this is still the most favored method with
that species. For the deep-rooted and shade-enduring fir the shelterwood
method with a long regeneration period was thoroughly established in
the Black Forest, and in Württemberg by 1818.
Natural regeneration being the main method of reproduction until the
beginning of the 19th century, _artificial_ means, as is evident from
the forest ordinances of Prussia and Bavaria (1812 and 1814), were
usually applied only to repair fail-places, or to plant up wastes. In
this artificial reforestation, with the exception of the planting of oak
in pastures, sowing was almost entirely resorted to because it could be
done cheaper and easier, but as the sowings were mostly made on
unprepared soil and with very large amounts of seed (30 to 60 pounds per
acre, now only 7 to 10 pounds), the results were not satisfactory,
either because the seed did not find favorable conditions for
germinating, or when germinated the stand was too dense.
Planting, if done at all, was done only with wildlings dug from the
woods, and usually, following the practice of the planting of oak in
pastures, with saplings: the plant material was too large for success.
Nurseries, except for oak, were not known, even to Cotta in 1817; and
Heyer, having to plant up several thousand acres, still relied on
wildlings, two to three years old, which he took up with a ball of earth
by means of his “hole spade,” a circular spade re-invented by him and
much praised by others. Hartig, in 1833, still advised the use of four
to five year old pine wildlings, root-pruned, but, eventually, having
met with poor success, for which he was much discredited, came to the
conclusion that un-pruned two-year-old plants were preferable.
The credit of having radically changed these practices belongs to Pfeil,
who, entirely reversing his position, advocated for pine forest a system
of clearing followed by sowing, or by planting of wildlings with a ball
of earth. Then, suggesting that possibly planting without this
precaution could be attempted, and pointing out the necessity of
securing a satisfactory root system, he recommended, about 1830, the use
of one-year-old seedlings grown in carefully prepared seed beds. While
for securing these, he relied upon the simple preparation of the soil by
spading, _Biermans_ added the use of a fertilizer in the shape of the
ashes of burned sod. The method of growing pine seedlings and planting
them when one to three years old was further developed by _Butlar_
(1845), who introduced the practice of dense sowing in the seed beds. He
also invented an ingenious planting iron or dibble, a half cone of iron,
which was thrown by the planter with great precision, first to make a
hole and then to close it. This was improved by the addition of a long
handle into the superior, well-known and much used _Wartenberg_ planting
dibble. At the same time (1840), _Manteuffel_ devised the method known
by his name of planting in mounds, which is especially applicable on wet
soils.
It was not until 1840 that transplanting of yearling pines with naked
roots became general. The widespread application of this latter system
resulted in abandoning to a large extent mixed growth, and led to the
establishment of pure pine forests, introducing thereby most intensively
all the dangers incident to a clearing system and pure forest which are
avoided by the mixed forest, namely, insects, frost and drought.
A practice of planting spruce in bunches, originally twelve to twenty
plants in a bunch, had been in existence since 1780. This practice
increased until 1850, and is still in use in the Harz mountains and in
eastern Prussia, although the bunches have been reduced so as to contain
only from three to five plants, the object of the bunching being to make
sure that one or the other of the plants should live. Much discussion as
to the merits of this method took place between the old masters, Cotta
favoring the small bunches upon the basis of a successful plantation of
his own, Hartig and Pfeil opposing it, but finally weakening. Since
1850, however, the practice of setting out single plants has become more
general.
A reaction from the indiscriminate application of the shelterwood method
to the hardwoods and of the clearing method to the pine set in during
the last quarter of the 19th century under the lead of Burkhardt and
Gayer. These advocated return to mixed forest and to natural
regeneration with long periods, approaching a selection forest. Gayer
especially, professor of silviculture at Munich, became the foremost
apostle of this school. Yet even to this day, the principles of
silvicultural treatment under the many different conditions remain
unsettled. On the whole however, with the financial question assiduously
brought forward, the clearing system has made most progress, and the
selection system has nearly vanished, being replaced by the group method
and the shelterwood system.
A number of special forms of silvicultural management applicable under
special conditions have been locally developed, without, however,
gaining much ground and being mainly of historical value. Among these
may be mentioned _Seebach’s Modified Beech Forest_, which consists in
opening up a beech stand so as to secure regeneration, merely to form a
soil cover, leaving enough of the old stand on the ground to close up in
thirty or forty years. By this treatment the large increment due to open
position is secured without endangering the soil. Similarly the
_Storied_ or _Two-aged High forest_, was applied to the management of
oak forest in mixture with beech. In a few localities also, on limited
areas, a combination of forest and farming (_Waldfeldbau_) has been
continued and elaborated, besides the more general use of coppice and
coppice with standards.
According to the statistics for 1900 the following distribution of the
acreage under different silvicultural methods prevailed throughout the
empire:
Deciduous Coniferous
Per cent. Per cent.
Total Forest 32.5 67.5
High Forest 18.4 60.1
Selection Forest 2.3 7.4
Coppice 6.8 --
Coppice with standards 5. --
Coniferous forest, of which 68% is pine and 30% spruce, prevails in
Eastern and Middle Germany, deciduous forest, of which 20% is oak, the
balance principally beech, in the West and South.
Coppice and coppice with standards are mostly in private hands as well
as the coniferous selection forest, the State forests being almost
entirely high forest, i.e., seed forest, other than under selection
method.
_Methods of Improving the Crop._ The credit of having first
systematically formulated the practice of thinnings under the name of
_Durchforstung_ (for the first thinning), _Durchplenterung_ (for the
later thinnings), belongs to Hartig, although the practice of such
thinnings had been known and applied here and there before his time. He
confined himself mainly to the removal of the undesirable species, dead
and dying, suppressed and damaged trees, being especially emphatic in
his advice not to interrupt the crown cover. Excepting the early weeding
or improvement cuttings, these thinnings were not to begin until the
fiftieth to seventieth year in the broadleaved forest, but in conifers
in the twentieth to thirtieth year.
The first attempt to explain on a biological basis the process and
effect of thinning was made by Späth in a special contribution (1802).
Cotta, in his Silviculture, although at first agreeing with Hartig,
later in his third edition (1821) changes his mind, and improves both
upon the biological explanation of Späth and the practice of Hartig,
pointing out that the latter came too late with his assistance, that the
struggle between the individuals should be anticipated, and the thinning
repeated as soon as the branches begin to die; but he also recognizes
the practical difficulty of the application of this cultural measure on
account of the expense. Curiously enough, he recommends severer
thinnings for fuel-wood production than for timber forests.
Pfeil accentuates the necessity of treating different sites and species
differently in the practice of thinnings. Hundeshagen accentuates the
financial result and the fact that the culmination of the average yield
is secured earlier by frequent thinnings. Heyer formulates the “golden
rule:” “Early, often, moderate,” but insists that first thinning should
not be made until the cost of the operation can be covered by the sale
of the material. Propositions to base the philosophy and the results of
thinning on experimental grounds rather than on mere opinion were made
as early as 1825 to 1828, and again from 1839 to 1846, at various
meetings of forestry associations, until, in 1860, Brunswick and Saxony
inaugurated the first more extensive experiments in thinnings. The two
representatives of forest finance, Koenig and Pressler, pointed out, in
1842 to 1859, the great significance of thinnings in a finance
management as one of the most important silvicultural operations for
securing the highest yield.
In spite of the advanced development of the theory of thinning, the
practice has largely lagged behind, because of the impracticability of
introducing intensive management. Only lately, owing to improvement in
prices and the possibility of marketing the inferior material profitably
enough to justify the expenditure, has it become possible to secure more
generally the advantages of the cultural effect. Within the last thirty
or forty years, great activity has been developed among the experiment
stations in securing a true basis for the practice of thinning.
New ideas were introduced through French influence and by others
independently in the latter part of the eighties, when the distinction
between the final harvest crop (Fr. élite, le haut) and the nurse crop
(le bas) was introduced.[4]
[4] The conception of such subdivision and the English nomenclature
was independently first employed by the writer in his Report for
1887, as Chief of Forestry Division, when discussing planting plans
for the prairies.
The physiological reasons for the practice of thinning upon experimental
basis, were advanced by the botanists Goeppert and R. Hartig, and among
foresters, the names of Kraft, Lorey, Haug, Borggreve, Wagener, and
others are intimately connected with the very active discussion of the
subject lately going on in the magazines. Thinnings have become such an
important part of the income of forest administrations (25 to 40% of the
total yield) that the prominence given to the subject is well justified,
and a more modern conception of the advantages of thinnings and
especially of severer thinnings is gaining ground.
The proposition, now much ventilated, of severe opening up near the end
of the rotation, in order to secure an accelerated increment
(_Lichtungshiebe_) is, however, much older; Hossfeld, in 1824, and Jäger
in 1850, advocated this measure for financial reasons, while Koenig and
Pressler anticipated the development of an individual tree management by
pruning, and differentiation of final harvest and nurse crop, a method
which is working itself out at the present time.