Alnus orientalis
Oriental alder

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Oriental alder (Alnus orientalis) is a medium-sized deciduous tree, usually reaching 15–25 m in height. It is native to south-western Asia, specifically Cyprus, southern Türkiye, north-west Syria, Lebanon, and Iran, where it typically grows along rivers and streams on wet, alluvial soils (Kurdali, 2000). It produces broad, serrated leaves that are shed seasonally, adding organic matter to soils, and catkins in spring for wind pollination. 

Oriental alder is a highly effective nitrogen fixer through symbiosis with bacteria, which allows it to thrive in nutrient-poor or disturbed soils and contribute to nutrient cycling and supporting surrounding vegetation (Kurdali, 2000). Its root systems stabilize riverbanks, reducing erosion, while its tolerance of polluted or waterlogged soils makes it particularly valuable for revegetation, erosion control, and ecological restoration projects (Kurdali, 2000). The species also has practical uses as an ornamental and forestry tree in some regions where it has been introduced outside its native range (Keet, Robertson, and Richardson, 2020). In South Africa, oriental alder outcompetes native riparian vegetation through shading, litter deposition, and changes to nutrient cycling, showing that it can be invasive in some contexts (Keet, Robertson, and Richardson, 2020). 

in situ genetic conservation unit+
ex situ genetic conservation unit+
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Acknowledgements

This distribution map has been developed by the European Commission Joint Research Centre (partly based on the EUFORGEN map) and released under Creative Commons Attribution 4.0 International (CC-BY 4.0)


Caudullo, Giovanni; Welk, Erik; San-Miguel-Ayanz, Jesús (2017). Chorological maps and data for the main European woody species. figshare. Collection. https://doi.org/10.6084/m9.figshare.c.2918528

 

The following experts have contributed to the development of the EUFORGEN distribution maps:

Fazia Krouchi (Algeria), Hasmik Ghalachyan (Armenia), Thomas Geburek (Austria), Berthold Heinze (Austria), Rudi Litschauer (Austria), Rudolf Litschauer (Austria), Michael Mengl (Austria), Ferdinand Müller (Austria), Franz Starlinger (Austria), Valida Ali-zade (Azerbaijan), Vahid Djalal Hajiyev (Azerbaijan), Karen Cox (Belgium), Bart De Cuyper (Belgium), Olivier Desteucq (Belgium), Patrick Mertens (Belgium), Jos Van Slycken (Belgium), An Vanden Broeck (Belgium), Kristine Vander Mijnsbrugge (Belgium), Dalibor Ballian (Bosnia and Herzegovina), Alexander H. Alexandrov (Bulgaria), Alexander Delkov (Bulgaria), Ivanova Denitsa Pandeva (Bulgaria), Peter Zhelev Stoyanov (Bulgaria), Joso Gracan (Croatia), Marilena Idzojtic (Croatia), Mladen Ivankovic (Croatia), Željka Ivanović (Croatia), Davorin Kajba (Croatia), Hrvoje Marjanovic (Croatia), Sanja Peric (Croatia), Andreas Christou (Cyprus), Xenophon Hadjikyriacou (Cyprus), Václav Buriánek (Czech Republic), Jan Chládek (Czech Republic), Josef Frýdl (Czech Republic), Petr Novotný (Czech Republic), Martin Slovacek (Czech Republic), Zdenek Špišek (Czech Republic), Karel Vancura (Czech Republic), Ulrik Bräuner (Denmark), Bjerne Ditlevsen (Denmark), Jon Kehlet Hansen (Denmark), Jan Svejgaard Jensen (Denmark), Kalev Jðgiste (Estonia), Tiit Maaten (Estonia), Raul Pihu (Estonia), Ülo Tamm (Estonia), Arvo Tullus (Estonia), Aivo Vares (Estonia), Teijo Nikkanen (Finland), Sanna Paanukoski (Finland), Mari Rusanen (Finland), Pekka Vakkari (Finland), Leena Yrjänä (Finland), Daniel Cambon (France), Eric Collin (France), Alexis Ducousso (France), Bruno Fady (France), François Lefèvre (France), Brigitte Musch (France), Sylvie Oddou-Muratorio (France), Luc E. Pâques (France), Julien Saudubray (France), Marc Villar (France), Vlatko Andonovski (FYR Macedonia), Dragi Pop-Stojanov (FYR Macedonia), Merab Machavariani (Georgia), Irina Tvauri (Georgia), Alexander Urushadze (Georgia), Bernd Degen (Germany), Jochen Kleinschmit (Germany), Armin König (Germany), Armin König (Germany), Volker Schneck (Germany), Richard Stephan (Germany), H. H. Kausch-Blecken Von Schmeling (Germany), Georg von Wühlisch (Germany), Iris Wagner (Germany), Heino Wolf (Germany), Paraskevi Alizoti (Greece), Filippos Aravanopoulos (Greece), Andreas Drouzas (Greece), Despina Paitaridou (Greece), Aristotelis C. Papageorgiou (Greece), Kostas Thanos (Greece), Sándor Bordács (Hungary), Csaba Mátyás (Hungary), László Nagy (Hungary), Thröstur Eysteinsson (Iceland), Adalsteinn Sigurgeirsson (Iceland), Halldór Sverrisson (Iceland), John Fennessy (Ireland), Ellen O'Connor (Ireland), Fulvio Ducci (Italy), Silvia Fineschi (Italy), Bartolomeo Schirone (Italy), Marco Cosimo Simeone (Italy), Giovanni Giuseppe Vendramin (Italy), Lorenzo Vietto (Italy), Janis Birgelis (Latvia), Virgilijus Baliuckas (Lithuania), Kestutis Cesnavicius (Lithuania), Darius Danusevicius (Lithuania), Valmantas Kundrotas (Lithuania), Alfas Pliûra (Lithuania), Darius Raudonius (Lithuania), Robert du Fays (Luxembourg), Myriam Heuertz (Luxembourg), Claude Parini (Luxembourg), Fred Trossen (Luxembourg), Frank Wolter (Luxembourg), Joseph Buhagiar (Malta), Eman Calleja (Malta), Ion Palancean (Moldova), Dragos Postolache (Moldova), Gheorghe Postolache (Moldova), Hassan Sbay (Morocco), Tor Myking (Norway), Tore Skrøppa (Norway), Anna Gugala (Poland), Jan Kowalczyk (Poland), Czeslaw Koziol (Poland), Jan Matras (Poland), Zbigniew Sobierajski (Poland), Maria Helena Almeida (Portugal), Filipe Costa e Silva (Portugal), Luís Reis (Portugal), Maria Carolina Varela (Portugal), Ioan Blada (Romania), Alexandru-Lucian Curtu (Romania), Lucian Dinca (Romania), Georgeta Mihai (Romania), Mihai Olaru (Romania), Gheorghe Parnuta (Romania), Natalia Demidova (Russian Federation), Mikhail V. Pridnya (Russian Federation), Andrey Prokazin (Russian Federation), Srdjan Bojovic (Serbia) , Vasilije Isajev (Serbia), Saša Orlovic (Serbia), Rudolf Bruchánik (Slovakia), Roman Longauer (Slovakia), Ladislav Paule (Slovakia), Gregor Bozič (Slovenia), Robert Brus (Slovenia), Katarina Celič (Slovenia), Hojka Kraigher (Slovenia), Andrej Verlič (Slovenia), Marjana Westergren (Slovenia), Ricardo Alía (Spain), Josefa Fernández-López (Spain), Luis Gil Sanchez (Spain), Pablo Gonzalez Goicoechea (Spain), Santiago C. González-Martínez (Spain), Sonia Martin Albertos (Spain), Eduardo Notivol Paino (Spain), María Arantxa Prada (Spain), Alvaro Soto de Viana (Spain), Lennart Ackzell (Sweden), Jonas Bergquist (Sweden), Sanna Black-Samuelsson (Sweden), Jonas Cedergren (Sweden), Gösta Eriksson (Sweden), Markus Bolliger (Switzerland), Felix Gugerli (Switzerland), Rolf Holderegger (Switzerland), Peter Rotach (Switzerland), Marcus Ulber (Switzerland), Sven M.G. de Vries (The Netherlands), Khouja Mohamed Larbi (Tunisia), Murat Alan (Turkey), Gaye Kandemir (Turkey), Gursel Karagöz (Turkey), Zeki Kaya (Turkey), Hasan Özer (Turkey), Hacer Semerci (Turkey), Ferit Toplu (Turkey), Mykola M. Vedmid (Ukraine), Roman T. Volosyanchuk (Ukraine), Stuart A'Hara (United Kingdom), Joan Cottrell (United Kingdom), Colin Edwards (United Kingdom), Michael Frankis (United Kingdom), Jason Hubert (United Kingdom), Karen Russell (United Kingdom), C.J.A. Samuel (United Kingdom).
 

Status of Alnus orientalis conservation in Europe

Genetic diversity and variation 

No detailed studies on the genetics of oriental alder appear to be available, and research is needed to understand these aspects. Studies covering Alnus as a genus have been carried out that include oriental alder. However, these only confirm that oriental alder can be genetically distinguished from other alder species, and that hybridization between oriental alder and common alder (Alnus glutinosa) occur, indicating genetic compatibility and potential introgression (Ren, Xiang, and Chen, 2010; Keet, Robertson, and Richardson, 2020). 

Gene flow 

Oriental alder has wind-dispersed pollen and seeds, allowing long-distance dispersal and promoting genetic connectivity. While wind disperses seeds short distances from the parent tree, seeds can be carried downstream along rivers and streams, enhancing local and downstream gene flow. These methods of gene flow maintain moderate to high genetic connectivity between populations, reducing inbreeding and promoting genetic diversity within populations. 

 

The bibliographic review was conducted by James Chaplin of the EUFORGEN Secretariat in August 2025.

NA

 

The bibliographic review was conducted by James Chaplin of the EUFORGEN Secretariat in August 2025.

Threats 

There is very little literature on genetic threats to oriental alder. Habitat loss and fragmentation are the main threats to the species in Europe, which can isolate riparian populations, reduce gene flow, and reduce population sizes, increasing the risk of inbreeding and allele loss. 

Management 

Conservation and management approaches include protecting and restoring riparian habitats, maintaining connectivity between populations to facilitate gene flow, and, where appropriate, monitoring and managing population sizes to preserve genetic variation. However, further research into the genetic diversity and genetic conservation of the species is needed to inform conservation efforts. 

 

The bibliographic review was conducted by James Chaplin of the EUFORGEN Secretariat in August 2025.

Genetic Characterisation of Alnus orientalis and its GCUs

Availability of FRM

FOREMATIS

Further reading

NA

References 

Keet, J.H., Robertson, M.P., and Richardson, D.M. 2020. Alnus glutinosa (Betulaceae) in South Africa: Invasive potential and management options. South African Journal of Botany, 135: 280–293. https://doi.org/10.1016/j.sajb.2020.09.009 

Kurdali, F. 2000. Seasonal nitrogen changes in Alnus orientalis and Populus nigra and N2 fixation by exotic alder species in Syria. Communications in Soil Science and Plant Analysis, 31(15–16): 2509–2522. https://doi.org/10.1080/00103620009370605 

Ren, B.Q., Xiang, X.G., and Chen, Z.D. 2010. Species identification of Alnus (Betulaceae) using nrDNA and cpDNA genetic markers. Molecular Ecology Resources, 10(4): 594–605. https://doi.org/10.1111/j.1755-0998.2009.02815.x 

If you notice any error in the contents of this species page, please contact euforgen@efi.int