Ordinary Douglas fir

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Ordinary Douglas fir
Douglas firs (Pseudotsuga menziesii) over 100 years old near Suhl / Thuringian Forest.

Douglas firs ( Pseudotsuga menziesii ) over 100 years old
near Suhl / Thuringian Forest.

Systematics
Class : Coniferopsida
Order : Conifers (Coniferales)
Family : Pine family (Pinaceae)
Subfamily : Laricoideae
Genre : Douglas firs ( Pseudotsuga )
Type : Ordinary Douglas fir
Scientific name
Pseudotsuga menziesii
( Mirbel ) Franco

The Douglas Fir ( Pseudotsuga menziesii ), often simply Douglas fir or colloquially Douglas fir , Douglas fir , Douglas pine or to the origin of Oregon pine called, is a plant of the genus of Douglas fir ( Pseudotsuga ). It is a foreign conifer that is native to North America and forest-grown in Europe .

description

Ripe cone
Ripe cones and seeds
Typical spiral-reinforced tracheids of a Douglas fir in a microscope

Appearance and needles

The Douglas fir is an evergreen tree . In Europe it reaches heights of growth of 60 meters. The tallest Douglas fir that has ever been found was 133 meters high; this is far taller than any tree still standing today (currently the tallest is a coastal redwood tree, about 116 meters tall in California ). The strongest specimens reach a trunk diameter of 4 meters at the base. The Douglas fir forms a relatively slender, conical crown .

The Douglas fir grows rapidly and can reach a maximum age of 400 ( Pseudotsuga menziesii var. Glauca ) to over 1400 ( Pseudotsuga menziesii var. Menziesii ) years. It has a heart-shaped root system. The seedlings have (eight to ten cotyledons cotyledons ).

The needles are green to blue-green, single, soft and blunt. They are 3 to 4 centimeters long and give off an aromatic, pleasant (lemon-like) odor when rubbed. In contrast to spruce, the Douglas fir needles sit directly on the branch; unlike fir trees , their base is not thickened.

Cones and seeds

The Douglas fir is single sexed ( monoecious ). The male cones are yellow-red. It blooms before budding and it is wind- blooming , but the pollen has no air sacs; There are also no pollination drops. The Douglas fir is capable of flowering at the age of 15 to 40 The cones have a length of 4 to 10 centimeters and a diameter of 3 to 3.5 centimeters. When ripe, they hang and fall off as a whole, like the spruce . The cover scales protrude far beyond the seed scales and are three-lobed at the top. The Douglas fir generally blooms from April to May in the northern hemisphere . The seeds ripen by September and are released from October to November. The seed is 5 to 6 millimeters long with a wing that is longer than the seed.

Chromosome number

The number of chromosomes is 2n = 26.

ecology

The common Douglas fir is a light germination and germination takes place above ground (epigeic).

The common Douglas fir is a shade-fast, fast-growing, evergreen conifer that can live up to 400 years; its forest rotation period is 60 to 100 years. In his homeland, in Pacific North America, 800-year-old trees were found with heights of growth of 70, rarely up to 90 meters and trunk diameters of about 2 meters; they are among the largest trees in the world. In 1991, a 929 year old specimen with a height of 90 meters was found in New Mexico at an altitude of 2070 meters.

The most common fungal pests for the Douglas fir are the "rusty Douglas fir chute " ( Rhabdocline pseudotsugae H.Sydow ) and the "sooty Douglas fir chute " ( Phaeocryptopus gaeumannii (Rohde) Petrak ). Both fungi are Ascomycetes (Ascomycetes); the infection by means of the spores occurs directly through the epidermis in the rusty or through the stomata of the leaves in the sooty Douglas fir. The symptom is a discoloration of the leaves from yellow-green to rust-brown. The needles are removed every year so that needled and unneedled annual shoots can occur next to each other on a branch. The coastal Douglas fir seems to be less susceptible to an infestation of the rusty Douglas fir, which is why it is preferred in Germany. Gray mold rot ( Botrytis cinerea Pers. ) Can also occur on Douglas firs.

Two herbivorous insect species from the North American area of ​​origin of the Douglas fir were unintentionally imported and have spread in Europe: the Douglas fir wool aphid (two species, Gilletteella cooleyi , Gilletteella coweni ) and the Douglas fir wasp ( Megastigmus spermotrophus ). The Douglas fir wool louse is one of the most important forest-damaging species in our country. In North America, the Douglas fir is considered to be the tree species with the highest diversity of invertebrate species that live on it. Around 140 phytophagous species use them as food here. In Europe, the Douglas fir is not generally populated with fewer species than the native species spruce and fir, contrary to older beliefs. Depending on the species group under consideration, the proportion of Douglas fir trees and the season, there are large differences, which is why a differentiated analysis is necessary. However, there are a number of specialized conifer colonists who have at least so far avoided the species, so that the Douglas fir is less populated than the native conifer species, especially in rare and highly specialized species (e.g. the species listed on the Red Lists). In Europe, for example, 24 species of bark beetle and 14 longhorn beetles have been detected on Douglas fir wood. According to the findings of the State Office for Nature, Environment and Consumer Protection in North Rhine-Westphalia, Douglas fir forests have a lower biodiversity and a lower density of individuals with birds, woodlice, spiders, ground beetles, weevils, ants, mosses, lichens and fungi as native tree species.

Douglas firs enter into a mycorrhizal symbiosis with the two-colored lacquer funnel , which can cause the seedlings to triple the biomass. Against this background, the fungus is used in the French Douglas fir to improve plant growth.

Occurrence

Natural range of the Douglas fir, green: Pseudotsuga menziesii var. Menziesii , blue: Pseudotsuga menziesii var. Glauca
Douglas fir group in the forestry experimental garden Grafrath ( district Fürstenfeldbruck )

The natural range of the Douglas fir ( Pseudotsuga menziesii ) is the west of North America, where it occupies large areas on the slopes of the Rocky Mountains and the cascade chain from British Columbia along the California Sierra Nevada to Mexico.

The Scottish botanist David Douglas brought the tree named after him to Kew Gardens near London from a North American expedition in 1827 . Since then, Douglas fir has been planted to a significant extent in Central Europe in the forest , but also in parks and gardens. Karl Philipp (1865–1937), who was appointed regional forest master and head of the Baden forest administration in 1924, and who was married to the Reichstag member Klara Philipp (center), is considered a pioneer of Douglas fir in Germany . He became one of the most controversial foresters of his time. Philipp got to know white pine and Douglas fir during a private stay in the USA in 1891/92. He ensured massive planting of these fast-growing tree species in Sulzburg and Freiburg. At the same time he moved under the motto Der Rechenstift teaches us that pure beech forests are bankrupt businesses, the traditional beech stocks, whereas the forest traditionalists and older experts like Hans Hausrath were in a real storm.

As an introduced species, the Douglas fir has proven itself in many countries around the world; it is by far the most important non-native forest tree species in Europe. The first, now 120-year-old attempts in Germany result in fascinating forest images depending on the subspecies. The largest and most massive Douglas fir population in Europe is in Kiekindemark near Parchim in the Sonnenberg nature reserve . In the terminal moraines by the Parchimer forestry Senator were area in the spring of 1882 W. Evers , the first stocks with Douglas fir seeds directly from the US government Washington created.

In Germany , according to the results of the Third National Forest Inventory (2012), with 218,000 hectares in the main stocking , the Douglas fir takes up around two percent of the total forest area, in the young stocking it is represented in a similar proportion with 40,000 hectares. The largest Douglas fir forest areas are found in Rhineland-Palatinate with 52,000 hectares (8.4 percent of the state forest area) and in Baden-Württemberg with 44,000 hectares (3.3 percent of the state forest area) . Between 2002 and 2012, the Douglas fir area in German forests increased by 35,000 hectares. The average increase in Douglas fir in Germany is 18.9 solid cubic meters per hectare and year. In 1900 a Douglas fir was planted in the Black Forest, which is currently the tallest tree in Germany with a height of 66 meters. This Douglas fir is called "Waldtraut".

The Douglas fir is not very common in Switzerland . They are less than 0.2% of all trees. It is most represented with approx. 0.6% in the Swiss plateau . From the 1850s, attempts were made to cultivate the Douglas fir in Switzerland and use it for forestry purposes. The largest population of Douglas firs is found in Switzerland in the municipality of Lohn-Ammannsegg in the canton of Solothurn . Around 1886 the then Lohner forester and cantonal forester Rudolf Stuber brought Douglas fir seeds from America to Switzerland, raised the seedlings and finally planted them in the "Lohner Forest" in 1891.

Tertiary occurrence in Europe

The genus of Douglas fir ( Pseudotsuga ) includes only four recent species, two of which occur in limited distribution areas in East Asia and two in western North America. In Europe the genus was represented in the Tertiary , certain finds are from the Oligocene ( Rupelium ) (Inntal, Austria) and the Miocene (Upper Lusatia, Germany), other finds concern fossil pollen and wood, especially the older finds are in the taxonomic classification very insecure. The fossil species were more similar to the more recent Asian Pseudotsuga species. There is no evidence of a European Douglas fir occurrence up to the Ice Age , as is assumed in some publications.

Site conditions and sociology

The common Douglas fir prefers mild winter locations in the lower mountain range.

It only needs a few fresh , deep soils with medium nutrient requirements. It thrives best in nutrient-rich soils that do not necessarily have to be rich in lime. Above all, they should be loamy and humic and not too rocky. The litter decomposition proceeds moderately slowly, the carbon-nitrogen ratio ( C / N ratio ) is 77. In contrast to spruce litter, Douglas fir litter does not cause soil acidification .

The common Douglas fir occurs in North America in societies of the plant sociological association Gaultherio-Pseudotsugion Knapp 57.

Systematics and taxonomy

The common Douglas fir ( Pseudotsuga menziesii ) was first named in 1825 by Charles François Brisseau de Mirbel (1776-1854) as Abies menziesii Mirb. first described. It was not until 1950 that the Portuguese botanist João Manuel António do Amaral Franco (1921–2009) placed it under the name Pseudotsuga menziesii (Mirbel) Franco in the genus Pseudotsuga .

The Douglas fir ( Pseudotsuga menziesii ) is divided into two varieties :

  • Coast Douglas fir ( Pseudotsuga menziesii (Mirbel) Franco var. Menziesii ; Syn .: Pinus taxifolia Lamb. Nom. Illeg., Abies taxifolia Poir. , Pinus douglasii Sabine ex D.Don , Pseudotsuga douglasii (Sabine ex D.Don) Carrière ) , also called Green Douglas Fir; this variety is grown for forestry in Germany. It is native to southeast Alaska, British Columbia, Washington, Oregon, and California.
  • Mountain Douglas-fir ( Pseudotsuga menziesii . Var glauca . (Beissn) Franco , Syn. : Pseudotsuga douglasii . Var glauca . (Beissn) Mayr , Pseudotsuga menziesii . Subsp glaucescens (Carriere) PDSell , Pseudotsuga menziesii var. Caesia (heavy) Franco. ) , also called blue or Colorado Douglas fir or inland Douglas fir. It originally occurs from the Rocky Mountains to central Mexico.

use

Douglas fir plywood

The wood of the Douglas fir can be used in many ways. When fresh, it is slightly reddish like larch wood and is used as veneer wood (peeling wood), equipment wood (parquet, furniture, paneling), construction wood for medium-duty use in interior, earthwork and hydraulic engineering, for windows, doors and special wood (ship masts, driven piles, Sleepers, barrels). The wood of the Douglas fir is essentially easier to impregnate than spruce and is considered to be the best wood for building roof trusses.

Douglas fir is one of the types of wood approved in Germany as construction timber for load-bearing structures. It has a higher natural durability (resistance) than, for example, spruce wood, which is often used as construction timber. The heartwood is classified according to DIN 68364 (1979) in resistance class 3 ("moderately durable") and can therefore be used without chemical wood protection in areas where occasional moistening is not excluded ( use class  2). It has an extremely low coefficient of thermal conductivity of 0.151 W / (m · K).

Picnic table made of new Douglas fir boards on a platform, also made of Douglas fir, which has been exposed to the weather for several years

After the Second World War , Douglas fir was cultivated in pure stands in Germany for rapid timber production, e.g. B. on the cool and humid plateaus of the Rhenish Slate Mountains . Also because of the decline in monocultures in the forest , only remnants are left today. Against the background of the looming climate change and the associated decrease in precipitation, the forestry use of the relatively drought-resistant Douglas fir could gain in importance again in Germany.

The resin is known as Oregon balm.

There have been attempts to extract wax from the bark .

The Douglas fir is also used as a Christmas tree because of its durability, but because of the delicate branches it is not suitable for overly heavy curtains.

Classification as an invasive neophyte

In Germany, the Douglas fir was classified as an invasive neophyte by the Federal Agency for Nature Conservation (BfN) : In 2013, it was added to the black list of invasive species by the BfN . Douglas fir dominates many types of soil, especially dry and acidic soils, and supplants native species. It only poses no problem on moist soils. According to the BfN, plantings should be at least within 300 meters of endangered habitat types, such as B. silicate rocks, are omitted and old trees are removed as soon as possible or young growth is gradually removed. In Austria the species is classified as potentially invasive. In Switzerland it is recommended not to grow Douglas firs within several hundred meters of protected biotopes. In contrast to Germany, the Douglas fir is not on the black list in Switzerland (as of 2014). These negative evaluations of nature conservation are questioned by some German forest scientists, who ascribe the Douglas fir in Central Europe only a small potential for displacing native species.

useful information

The Douglas fir Waldtraut from Mühlwald is the tallest tree in Germany

The tallest tree in Germany is in the Freiburg-Günterstal arboretum . This more than 100 year old Douglas fir forest traut from Mühlwald in the city forest of Freiburg im Breisgau in the Günterstal district is (as of April 2017) 66.58 m high and thus higher than the Douglas fir in the Eberbacher Stadtwald, which was previously the tallest tree in Germany (as of 2017: 63.3 m).

The Douglas fir is the state tree of the US state Oregon .

In 2011, an extensive forest science study was published (Albrecht et al., 2011), which shows that contrary to the theses often put forward, Douglas firs in Baden-Württemberg have as high a windthrow risk as spruce trees. Here is a quote from the conclusions: “After taking into account stand dimensions, site characteristics and silvicultural interventions, it becomes apparent that the storm risk of Douglas fir on the investigated long-term forest growth test areas is as high as that of spruce. Silvicultural systems for Douglas fir in Central Europe should be revised against the background of a generally high storm risk potential. "

literature

  • Phan Hoang Dong (Ed.): On the cultivation and growth of the Douglas fir. (= Messages from the Research Institute for Forest Ecology and Forestry Rhineland-Palatinate. No. 55). Research Institute for Forest Ecology and Forestry Rhineland-Palatinate, Trippstadt 2005.
  • Renate Bürger-Arndt: Knowledge of the synecology of the Douglas fir as a basis for a nature conservation assessment. In: Forest and Wood. 55 (22), 2000, pp. 707-712. ISSN  0932-9315 .
  • Frantisek Hapla, Wolfgang Knigge: Investigation of the effects of thinning measures on the wood properties of the Douglas fir. (= Writings from the Forestry Faculty of the University of Göttingen and the Lower Saxony Forest Research Institute. Volume 81). Sauerländer, Frankfurt am Main 1985, ISBN 3-7939-5081-6 .
  • Armin Heidingsfelder, Thomas Knoke : Douglas fir versus spruce. A business performance comparison based on the provenance experiment in Kaiserslautern. (= Writings on forest economics. Volume 26). Sauerländer, Frankfurt am Main 2004, ISBN 3-7939-7026-4 .
  • Horst Kramer : Growth and Treatment of Douglas Fir in the Pacific Northwest of America. (= Writings from the Forestry Faculty of the University of Göttingen and the Lower Saxony Forest Research Institute. Volume 75). Sauerländer, Frankfurt am Main 1983, ISBN 3-7939-5075-1 .
  • Kurt Göhre u. a .: The Douglas fir and its wood . Akademie-Verlag, Berlin (GDR) 1958.
  • Martin Gossner: diversity and structure of arboreal arthropods coenoses of exotic and native trees. A contribution to the evaluation of the cultivation of Douglas fir (Pseudotsuga menziesii (Mirb.) Franco) and red oak (Quercus rubra L.). In: Neobiota. 5, 2004. ISSN  1619-0033 .
  • Dietrich Knoerzer: On the natural regeneration of the Douglas fir in the Black Forest. Inventory and analysis of environmental and competitive factors as well as a nature conservation assessment. (= Dissertationes Botanicae. 306). J. Cramer in the Gebrüder Borntraeger Verlagbuchhandlung , Berlin / Stuttgart 1999, ISBN 3-443-64218-7 .
  • Anton Rieder: The Douglas fir: an attractive commercial tree for Central Europe. Basics and arguments for an intensification of the Douglas fir cultivation. Published by the Austrian Federal Forests AG. Publishing House Library of the Province, Weitra 2014, ISBN 978-3-901862-28-1 .
  • Peter Schütt, Horst Weisgerber, Hans J. Schuck, Ulla Lang, Bernd Stimm, Andreas Roloff: Lexicon of Conifers. Distribution - Description - Ecology - Use; the great encyclopedia . Nikol, Hamburg 2004, ISBN 3-933203-80-5 .
  • Ruprecht Düll , Herfried Kutzelnigg : Pocket dictionary of plants in Germany and neighboring countries. The most common Central European species in portrait. 7th, corrected and enlarged edition. Quelle & Meyer, Wiebelsheim 2011, ISBN 978-3-494-01424-1 .
  • Dietmar Aichele, Heinz-Werner Schwegler: The flowering plants of Central Europe. Volume 2, 2nd revised edition, Franckh-Kosmos-Verlag, 2000, ISBN 3-440-08048-X .

Individual evidence

  1. ^ Ordinary Douglas fir at Tropicos.org. Missouri Botanical Garden, St. Louis.
  2. ↑ Martin Gossner: Diversity and structure of arboricoler arthropod communities of foreign and native tree species. A contribution to the evaluation of the cultivation of Douglas fir (Pseudotsuga menziesii (Mirb.) Franco) and red oak (Quercus rubra L.). In: Neobiota. 5, 2004. ISSN  1619-0033 .
  3. ↑ Carla Michels: Douglas fir - an invasive species? Nature in NRW 4/2014, pp. 27–31
  4. ↑ JG Huang, F. Lapeyrie: Ability of ectomycorrhizal fungus Laccaria bicolor S238N to increase the growth of Donglas Fir seedlings and their phosphorns and potassinm uptake. In: Pedosphere. 4 (3), 1994, pp. 217-224.
  5. ↑ http://bioinformatics.psb.ugent.be/ (accessed on May 25, 2013)
  6. ↑ J. Weber, J. Díez, MA Selosse, D. Tagu, F. Le Tacon: SCAR markers to detect mycorrhizas of an American Laccaria bicolor strain inoculated in European Douglas-fir plantations. In: Mycorrhiza. 12 (1), 2002, pp. 19-27. PMID 11968943 , doi : 10.1007 / s00572-001-0142-9 .
  7. ↑ a b c Entry on Philipp at LEO-BW, regional information system for Baden-Württemberg
  8. ↑ John Richmond Booth , owner of the nursery James Booth and sons , had already in 1831 a Douglas fir in the Jenisch Park in time to Altona belonging Othmarschen planted. He and his son John Cornelius Booth had planted well over 500 Douglas firs on the lands of the Hamburg merchant Cesar Godeffroy between 1842 and 1872.
  9. ↑ Hans Hausrath : Guidelines for the education and regeneration of the high forest in Baden. A critical consideration. In: AFJZ. 101, 1925, pp. 438-444.
  10. ↑ Douglas firs felt to the tooth In: Schweriner Volkszeitung . November 16, 2013.
  11. ^ Fritz Hackert: On the introduction of foreign wood species in the Kiekindemark district. In: Heimatbund Parchim (ed.): Pütt Heft 1985. Parchim 1987, (PDF file; 130 kB).
  12. ↑ F. Kroiher, A. Bolte: Nature conservation and biodiversity in the mirror of the BWI 2012. In: AFZ-Der Wald. 21/2015.
  13. ↑ National Forest Inventory 3, 2012 . Retrieved July 2, 2016.
  14. ^ Federal Research Institute for Forests, Snow and Landscape WSL: Douglas fir
  15. ↑ 300 new Douglas firs for the forest in Lohn-Ammannsegg. In: SRF . 17th March 2016.
  16. ↑ The 300 Douglas firs for Lohner Wald have already been donated. In: Aargauer Zeitung . 17th March 2016.
  17. ↑ Rainer Butzmann, Thilo C. Fischer, Ernst Rieber: Macroflora from the inner-Alpine fan delta of the Häring formation (Rupelium) from Duxer Köpfl near Kufstein / Unterinntal, Austria. In: Zitteliana Series A. 48/49, 2009, pp. 129–163, urn : nbn: de: bvb: 19-epub-11981-2 .
  18. ↑ A. Czaja: Pseudotsuga jechorekiae sp. nova, the first fossil record of the genus Pseudotsuga Carrière after cones from the Miocene of Upper Lusatia, Germany. In: Feddes Repertorium 111, 2000, pp. 129-133. doi : 10.1002 / fedr.20001110302 .
  19. ^ RK Hermann: The genus Pseudotsuga: ancestral history and past distribution. Forest Research Laboratory, Oregon State University 1985, Special Publication 2b, online (PDF; 465 kB).
  20. ^ Erich Oberdorfer : Plant-sociological excursion flora for Germany and neighboring areas . With the collaboration of Angelika Schwabe and Theo Müller. 8th, heavily revised and expanded edition. Eugen Ulmer, Stuttgart (Hohenheim) 2001, ISBN 3-8001-3131-5 , pp.  91 .
  21. ↑ Christopher J. Earle: Pseudotsuga menziesii. In: The Gymnosperm Database , 2008. (Eng.)
  22. ↑ a b Rafaël Govaerts (Ed.): Pseudotsuga. In: World Checklist of Selected Plant Families (WCSP) - The Board of Trustees of the Royal Botanic Gardens, Kew . Retrieved April 13, 2019.
  23. ↑ Peter Niemz: Investigations into the thermal conductivity of selected native and foreign wood species . In: Building Physics 29 . tape 29 , no. 4 . Ernst & Sohn Verlag for Architecture and Technical Sciences GmbH & Co.KG, Berlin 2007, p. 311-312 , doi : 10.1002 / bapi.200710040 .
  24. ^ Ministry for Climate Protection, Environment, Agriculture, Nature and Consumer Protection of the State of North Rhine-Westphalia (Ed.): State Forest Report North Rhine-Westphalia 2007. Düsseldorf 2007, p. 75 (PDF file; 4.6 MB).
  25. ^ Karl Dieterich, Erich Stock: Analysis of the resins. 2nd edition, Springer, 1930, ISBN 978-3-642-89462-6 , pp. 45 f.
  26. ↑ FA Loewus, VC Runeckles: The Structure, Biosynthesis, and Degradation of Wood. In: Recent Advances in Phytochemistry. Vol. 11, 1977, p. 458, doi : 10.1007 / 978-1-4615-8873-3 , Plenum Press, 1977, ISBN 978-1-4615-8875-7 .
  27. ^ NIIR Board of Consultants & Engineers: The Complete Technology Book on Wax and Polishes. Asia Pacific Business Press Inc., 2011, ISBN 978-81-7833-012-9 (Reprint), p. 47 f.
  28. ^ EF Kurth: The Composition of the Wax in Douglas-Fir Bark. In: J. Am. Chem. Soc. 1950, 72 (4), pp. 1685-1686, doi : 10.1021 / ja01160a072 .
  29. ↑ Stefan Nehring, Ingo Kowarik , Wolfgang Rabitsch, Franz Essl (eds.): Nature conservation-related invasiveness assessments for alien vascular plants living in the wild in Germany. (= BfN-Skripten 352, 2013) ( PDF ; 2.1 MB).
  30. ↑ Carla Michels: Douglas fir - an invasive species? Nature in NRW 4/2014, pp. 27–31
  31. ^ Black list Lists of invasive neophytes in Switzerland - August 2014 .
  32. ↑ Effects of Douglas fir on forest biodiversity: A literature review from the Swiss Federal Research Institute for Forests, Snow and Landscape WSL, 2014.
  33. ^ Open letter from German forest scientists dated June 4, 2014 to the BfN
  34. ↑ Volkmar Weiss: No welcoming culture for Douglas firs in the German forest? Neustadt an der Orla: Arnshaugk 2017, ISBN 978-3-944064-76-5 , review by Thomas Wohlgemuth in: Swiss Journal for Forestry 169 (2018) p. 119 [1]
  35. ↑ Germany's tallest tree is in Freiburg. In: Stuttgarter Zeitung. August 18, 2008, archived from the original on June 19, 2011 ; Retrieved November 4, 2011 .
  36. ↑ Dorothea Dörner: "Waldtraut" is Germany's tallest tree. In: Frankfurter Neue Presse. April 25, 2017. Retrieved September 20, 2017 .
  37. ↑ Axel Albrecht, Ulrich Kohnle u. a .: Storm risk of spruce versus Douglas fir on test areas in Baden-Württemberg. ( Memento from April 2, 2015 in the Internet Archive ) DVFFA annual conference 2011.

Web links

Commons : Common Douglas Fir ( Pseudotsuga menziesii )  - Collection of images, videos, and audio files
Wiktionary: Douglas fir  - explanations of meanings, word origins, synonyms, translations