Alfred Dengler

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Memorial plaque for Alfred Dengler

Alfred Dengler (born March 23, 1874 in Berlin ; † October 15, 1944 in Eberswalde ) was a German forest scientist .

Life

The Dengler family originally comes from Silesia. His parents were the secret chancellery Ludwig Dengler (1834-1919) and his wife Klara Rasim (1847-1935), a daughter of the forester Anton Rasim († 1878).

Dengler studied forest science at the Eberswalde Forest Academy . After graduating in 1901, he finished a few semesters of botany at the Ludwig-Maximilians University in Munich and was there in 1903 with a thesis on the arealgeografischen pine ( Pinus sylvestris L.) with "summa cum laude" doctorate . He then worked as an assistant at the Botanical Institute in Eberswalde and one year at the Plant Physiological Institute of the University of Berlin. From 1912 to 1921 he headed the state forest ranger in Reinhausen in southern Lower Saxony and led silvicultural courses at the forest academy in Hann. Münden and the University of Göttingen. During the First World War he was mainly used as the head of a forestry command in Romania. From 1921 to 1927, he succeeded Max Kienitz as head of the teaching forest ranger's office in Chorin at the Eberswalde Forestry University and the associated teaching duties.

In 1922, Dengler was appointed to the chair of silviculture at the Eberswalde Forestry University as the successor to the late Alfred Möller and as head of the institute for silviculture ("Möller Institute"). In November 1933 he and about 900 other university lecturers signed the professors' commitment to Adolf Hitler at German universities and colleges . Dengler retired in 1939, but took over his old office again in 1941, replacing his successor, Professor Dr. Herbert Hesmer . The clearly emerging collapse of Germany, health and, above all, family reasons made him end his life himself on October 15, 1944 at the age of 71, despite a life rich in honors and awards. His grave is in the Chorin monastery cemetery .

He married Elisabeth Lade (1881–1952) in Kronberg (Taunus) in 1909 , the daughter of forester Ernst Lade (1849–1921) and Auguste Kleinschmidt . The couple has a son ( Gerhard Dengler ) and two daughters. One of the daughters, Hilde Dengler, marries Eilhard Wiedemann (* 1891), professor, head of the Lower Saxony Forest Research Institute.

Scientific work

1. Plant geography works

Mainly in the first decade (1901–1913) of his scientific activity, Dengler researched the natural distribution of pine, spruce and silver fir. At that time the only working method available to him was archival studies. The results were later confirmed by pollen analyzes.

2. Silvicultural work

After taking up the silviculture professorship and taking over the silviculture institute until his retirement in 1939, Dengler published numerous scientific research results on questions of practical silviculture. They mainly concerned the pine culture technique such as B. the optimal coverage depth of the pine seed (which led to the construction of the then generally introduced "Walddank" seed drill). He further investigated the dependence of plant development on the seed density, the high and low planting of the pine, the influence of tillage, structure and growth behavior of an old mixed pine-beech stand and the crown structure and growth of old pines from the Brandenburg region. In addition, publications were produced on the primeval fir, beech and pine forest, the cultivation of Japanese larch and the systematic structure of silvicultural operations. From his lecture he developed the textbook silviculture on an ecological basis , which appeared in three editions in 1930, 1935 and 1944. It was then reissued several times by Ernst Röhrig together with various co-authors: 4th edition 1971/72 in two volumes with A. Bonnemann, 5th edition 1980/82 in two volumes alone, 6th edition 1990/92 in two volumes with N. Bartsch and HA Gussone, 7th edition 2006 in one volume with Norbert Bartsch and Burghard von Lüpke . It is still the standard work on silviculture in Germany.

3. Forest genetic work

Apart from an evaluation of the oldest pine provenance tests in Germany published in 1908, Dengler has mainly been concerned with forest genetic studies in the last 15 years of his life, some of which were only published from the estate 10 years after his death. In 1928, 1929 and 1933 he was the first in Germany to conduct controlled cross-breeding experiments with pines of different origins, which yielded important findings for provenance research. This was followed by further attempts at crossbreeding between Japanese and European larch, English oak and sessile oak, mountain and Scots pine, as well as single-stem sowing of oak, beech, spruce and pine, provenance tests with Brandenburg and Turkish pines, spruce and larch origins and studies on the blossom biology of the pine and germination physiology of tree pollen. Dengler emphasized the importance of this research area, but also repeatedly pointed out the importance of the individual tree selection in practical operation during thinning operations.

Dealing with the permanent forest movement

Alfred Möller , in an essay in 1920 about "pine- permanent forest management " and in his work The permanent forest thought, published shortly before his death in 1922, took the view that the forest is an organism that is only healthy and capable of maximum wood production in harmony with all of its organs. Since the soil is also an organ of the forest organism, clear cutting is a "murder of the forest creature". This resulted in the following requirements for practical forest management: 1. The state of equilibrium of all the members peculiar to the forest; 2. Soil health and activity; 3. mixed forest; 4. Disparity; 5. Sufficient supply of solid wood everywhere.

Dengler not only rejected the exaggerations of the permanent forest concept (as represented by Wiebecke, Lüderßen and many others after Möller's death), but also the core of the idea, namely the conception of the forest as an organism. This becomes very clear in his lecture at the 1925 Forest Association Conference in Salzburg: “But the forest is not an organism in this sense. Its members: Soils, plants and animals are not mere organs (organs = tools) that are only intended to serve the organism and, detached from it, lose viability and function. Rather, they primarily serve themselves and can also live outside the forest as a whole - even if often only in a different form and in a less perfect way. Plant geography has already found a more appropriate and correct expression for this idea by Rossmaessler : community or biocenosis. It's not quibbling or narrow-mindedness. Because the resulting conclusion is serious: The connection between the parts is much looser and not inseparable, the mutual dependency is there, but not as strong and as unconditional as in the case of the organism. ”With this view, Dengler came to today's view of the forest as an ecosystem very close. Dengler also rejected the natural-philosophical justification for an organismic understanding of the forest, as his colleague Hans Lemmel advocated in 1939.

From his scientific and practical forestry point of view, it was not the theoretical and philosophical thoughts that were decisive, but their effects on the practice of forest management. An example of this way of thinking is Dengler's position on the general rejection of clear-cutting by the supporters of the permanent forest movement (contained in the above-cited article Zu Lemmel's criticism of my position on the concept of permanent forest ): The nature of clear-cutting cannot be judged from the preconceived notion of the forest as an organism but only through exact, ie comparative studies of soil and stand after clearing and under stand. According to this, the harmfulness of the deforestation for the East German pine industry has not yet been proven, on the contrary, for the rejuvenation of the pine trees it is almost always beneficial. Pine trees cannot be rejuvenated naturally under umbrella everywhere as well as under the special soil and stand conditions in the private forest enterprise Bärenthoren in the first decades of the 20th century. As with many other statements by Dengler, it becomes clear here that, in contrast to the permanent forest supporters, he was careful not to make generalizations and always emphasized the influences of location and stand. In his above-mentioned speech at the conference of the German Forestry Association in 1925, he formulated the following guiding principles: “Permanent forest management has only partially achieved successes, but these are always due to particular local circumstances. Nevertheless, there is much that is good and right in thought if you stay away from exaggeration. However, in forestry, as in any other technology, the line of development does not go 'back to nature', but to ever greater 'control of nature' ”.

The question of pine tree regeneration under umbrella has become the central object of controversy in the ongoing forest disputes over the years. Dengler tried to solve it, firstly by evaluating the regeneration successes on the feeding surfaces of the pine owl ( Panolis flammea ), and then through a large-scale study of the dependence of natural pine regeneration on location and management. Unfortunately, this extensive work was destroyed by the Second World War.

Dengler described himself as a conditional supporter of the permanent forest movement. He particularly supported one of their main demands, namely the abandonment of an exaggeratedly large-scale pure stock management, even when he recognized "that the pendulum, as always in history, now swings to the other side".

From 1933 to 1937, the Prussian general forest master Walter von Keudell ordered permanent forest management throughout Germany. It thus became a forest state ideology, and it was not without risk to contradict it. Dengler rejected this rigorous generalization of the permanent forest principles, which meant that he, like other critical professors in Eberswalde (e.g. Walter Wittich and Eilhard Wiedemann ), was forbidden from holding examinations. Only when v. Keudell was replaced by Friedrich Alpers , the sole validity of the permanent forest principles ended by a fundamental decree of the Reich Forest Master. Dengler was fully rehabilitated and employed as Alpers' personal advisor.

Honors

A street was named after him in the Brandenburg city of Eberswalde.

Works

  • Silviculture on an ecological basis , Berlin, Verlag J. Springer, 1930.

Individual evidence

  1. ↑ Alfred Dengler: Investigations into the natural and artificial distribution areas of some forest and plant-geographically important types of wood in northern and central Germany. 1. The horizontal distribution of the pine. Neudamm . 1904.
  2. ↑ Alfred Dengler: The horizontal spread of the spruce. Neudamm, 1912.
  3. ↑ Alfred Dengler: About the effect of the depth of cover on germination and the first development of pine seeds. In: Zeitschrift für Forst- und Jagdwesen 1925, pp. 385–408.
  4. ^ Alfred Dengler: The main questions of a modern design of our East German pine industry. In: Zeitschrift für Forst- und Jagdwesen Volume 60, 1928, pp. 65-100
  5. ^ Alfred Dengler: Analysis of an old mixed pine and beech stand. In: Zeitschrift für Forst- und Jagdwesen Volume 67, 1935, pp. 401-420.
  6. ↑ Alfred Dengler: From the south-east European primeval forests. II. The results of a test area survey in the beech forest of Albania. In: Zeitschrift für Forst- und Jagdwesen Volume 63, 1931, pp. 20–32.
  7. ^ Alfred Dengler: Saumschlag and North German pine farming. In: Zeitschrift für Forst- und Jagdwesen Volume 64, 1932, pp. 743–753.
  8. ^ Ernst Röhrig , Norbert Bartsch and Burghard von Lüpke : Silviculture on an ecological basis. 7th edition, Eugen Ulmer, Stuttgart 2006, ISBN 3-8001-4595-2 .
  9. ^ Alfred Dengler: The growth of pines from local and Nordic seeds in the Eberswalde forestry department. In: Zeitschrift für Forst- und Jagdwesen Volume 40, 1908, pp. 137–152, 206–219.
  10. ↑ Alexis Scamoni : The forest genetic work of Prof. Dr. Dr. hc Alfred Dengler. In: Journal for Forest Plant Breeding and Forest Genetics , Volume 4, 1955, pp. 103-107.
  11. ↑ Alfred Dengler: About the development of artificial pine crossings. In: Zeitschrift für Forst- und Jagdwesen Volume 71, 1939, pp. 457-485.
  12. ^ Alfred Dengler: Report on attempts to cross between sessile oak and pedunculate oak and between European and Japanese larch. In: Communications from the Academy of German Forest Science , 1940, pp. 87–109.
  13. ↑ Alfred Dengler: About the fertility of the female pine blossom. In: Zeitschrift für Forst- und Jagdwesen Volume 72, 1940, pp. 48–54.
  14. ↑ Alfred Dengler and Alexis Scamoni: About the pollen count of forest trees. In: Journal for the entire forest system 1944, pp. 136–155.
  15. ^ Alfred Möller: Pines - permanent forest management. Investigations from the forest of the Chamberlain von Kalitsch in Bärenthoren, district Zerbst. In: Journal of Forestry and Hunting. Volume 52, 1920, pp. 4-41.
  16. ↑ Alfred Möller: The permanent forest thought. Its meaning and its meaning. J. Springer Verlag, Berlin 1922.
  17. ^ Alfred Dengler: The permanent forest question in theory and practice. In: Annual Report of the German Forest Association 1925, pp. 129–144, 149–152
  18. ^ Alfred Dengler: On Lemmel's criticism of my position on the permanent forest idea. In: Zeitschrift für Forst- und Jagdwesen Volume 71, 1939, pp. 553-561.
  19. ↑ Alfred Dengler: Bärenthoren 1934. the natural economic forest. In: Zeitschrift für Forst- und Jagdwesen Volume 68, 1936, pp. 337–353.
  20. ↑ Alfred Dengler: Single family economy. In: Zeitschrift für Forst- und Jagdwesen Volume 67, 1935, pp. 1–15.
  21. ↑ Alfred Dengler: Turning point in silviculture. In: Silva Volume 25, 1937, pp. 21-25.
  22. ^ Alfred Dengler: On the dispute about the permanent forest in theory and practice. Epilogue to: Lüderßen: permanent forest! In: Silva , 1925, pp. 209-210.
  23. ^ Letter to a permanent opponent of the forest, quoted in: Eilhard Wiedemann: Zum Scheiden von Prof. Dr. Dr. hc Alfred Dengler. In: Communications from the Academy of German Forest Science, 1945, p. 435.
  24. ^ J. Heyder: Silviculture in Transition. Sauerländer's Verlag, 1986, Frankfurt a. M.

Web links

personal data
SURNAME Dengler, Alfred
BRIEF DESCRIPTION German forest scientist
DATE OF BIRTH March 23, 1874
PLACE OF BIRTH Berlin
DATE OF DEATH October 15, 1944
Place of death Eberswalde