To learn more about the map elements, please download the "Pan-European strategy for genetic conservation of forest trees"
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, G., Welk, E., San-Miguel-Ayanz, J., 2017. Chorological maps for the main European woody species. Data in Brief 12, 662-666. DOI: https://doi.org/10.1016/j.dib.2017.05.007
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 Fraxinus excelsior conservation in Europe
Across central Europe, European ash has high genetic diversity and low genetic differentiation due to effective pollen and seed dispersal over long distances, meaning that even small and isolated populations have high gene flow (Semizer-Cuming, Kjær, and Finkeldey, 2017).
Differentiation is observed between cultivated and native trees, likely the result of forest management, artificial selection, and breeding (Semizer-Cuming, Kjær, and Finkeldey, 2017). However, mixing of seed sources in cultivation can increase genetic diversity, and this may be why some varieties in Germany have higher genetic diversity than those elsewhere (Dacasa Rüdinger et alk., 2008). German populations show high levels of genetic diversity, low levels of inbreeding, and low differentiation with no isolation by distance observed (Dacasa Rüdinger et alk., 2008; Semizer-Cuming, Kjær, and Finkeldey, 2017). Populations in Bosnia and Herzegovina also show high diversity and low differentiation because they may be in a contact zone between central European and Balkan populations (Ballian et al., 2008).
Unlike in Germany, Bosnian populations show inbreeding, which is expected as European ash has the inclination to inbreed (Ballian et al., 2008). Inbreeding in Italian populations also was shown to be high, the reason for this being unclear. Despite this, Italian populations still demonstrated high gene flow, high genetic diversity, and low differentiation, with only 4.9% of genetic variation being between populations (Ferrazzini, Monteleone, and Belletti, 2007).
Some clustering is observed, with the possible existence of one “floodplain” ecotype and one “limestone” ecotype of European ash in Germany (Dacasa Rüdinger et al., 2008). However, the differentiation between these two ecotypes is likely the result of genetic drift, human pressure, and seed transport, not necessarily environmental selective pressures such as flooding (Dacasa Rüdinger et al., 2008). Populations in Bosnia and Herzegovina show some grouping based on different climatic conditions (Ballian et al., 2008).
The bibliographic review was conducted by James Chaplin of the EUFORGEN Secretariat in August 2024.
During the Quaternary glacial period, European ash had glacial refugia in the Iberian Peninsula, the Alps, Italy, and the Balkan Peninsula (Pliûra and Heuertz, 2003). Glacial refugial populations in the northern Apennines and on the northern Black Sea coast likely colonized most of northern Europe, which may be why there is high differentiation between south-eastern European and northern central European populations (Ferrazzini, Monteleone, and Belletti, 2007).
The bibliographic review was conducted by James Chaplin of the EUFORGEN Secretariat in August 2024.
On the European scale, common ash is not an endangered species, although its range and population sizes have decreased (Pliûra and Heuertz, 2003). Threats to the tree’s genetic resources include deforestation, loss of suitable habitats, unsustainable exploitation and improper management (i.e. uncontrolled transfer of reproductive material), climatic change, air pollution, competition with other species, pests, diseases, especially fungus (such as Hymenoscyphus fraxineus, which causes ash dieback and can kill up to 90% of all ash trees in a population), and game damage (Pliûra and Heuertz, 2003; Semizer-Cuming, Kjær, and Finkeldey, 2017).
However, European ash has high economic value and is of key commercial interest, and genetic variability is typically intact as natural regeneration is normally used in forestry practices, although reproductive material from nurseries is sometimes used (Ferrazzini, Monteleone, and Belletti, 2007).
A Multiple Population Breeding System should be applied, subdividing breeding populations into subpopulations that are then grown over a wide range of site conditions (Pliûra and Heuertz, 2003). Such an approach should include valuable populations. South-eastern European and northern central European populations are highly differentiated and thus have populations high conservation value (Pliûra and Heuertz, 2003). However, inventories should be carried out to identify the geographical distribution of the species, conservation status, threats, and potential use patterns to identify relevant populations (Pliûra and Heuertz, 2003). In situ management networks of large populations should be established to increase their adaptive potential by ensuring natural regeneration, while smaller populations that are marginal, isolated, under threat, and/or growing under special ecological conditions should be included in ex situ conservation (Pliûra and Heuertz, 2003).
The bibliographic review was conducted by James Chaplin of the EUFORGEN Secretariat in August 2024.
Genetic Characterisation of Fraxinus excelsior and its GCUs
Availability of FRM
FOREMATIS
Fraxinus excelsior - Technical guidelines for genetic conservation and use for common ash
Publication Year: 2003Genetic conservation aims at ensuring continuous survival and adaptability of the target species. These objectives are met when the Multiple Population Breeding System (MPBS) is applied. Ideally in MPBS, a breeding population is subdivided into subpopulations which are then grown over a wide range of site conditions.
In each country where common ash is found, an inventory should be undertaken to define the geographical distribution of the species, conservation status, threats and potential use patterns. Ecogeographic zones (provenance regions) should be delimited according to climatic variation, topography, soil and vegetation. Trees are generally best adapted to the ecological conditions of the region where they evolved. Therefore, local material should be used for plantations wherever possible, unless otherwise recommended as the result of data from provenance trials.
To ensure the adaptive potential of Fraxinus excelsior in Europe, it is recommended that two complementary gene conservation networks of populations are established, specifically: (1) a network of 20-30 in situ populations throughout provenance regions; and (2) a network of ex situ populations (progeny trials, provenance trials, collections). Whenever possible, in situ conservation activities should be undertaken jointly for other Noble Hardwoods.
Where common ash occurs in large populations in a country, in situ conservation is sufficient, with the selection of up to three gene conservation populations/ gene reserves of 5-15 ha in size, with at least 100 flowering trees in each provenance. A high density of in situ gene conservation populations should be established in Southeast Europe, especially in Romania and Bulgaria, which have been colonised by populations from different ice age refuges. In these regions, neutral genetic markers show high differentiation among populations, suggesting that they may have different potentials to cope with future climatic conditions. Specific conservation efforts are also recommended in northern central Europe, due to the high level of differentiation between populations in southern Sweden, although the historical origin of this differentiation still needs to be verified.
In situ gene conservation populations need to be managed to increase their adaptive potential by ensuring the natural regeneration of the target species, creating multi-age structure and habitat diversity, and increasing generation turnover.
To conserve an even-aged mature stand in situ, parts of the population should be opened (thinned or cut in narrow strips of 15-30 m width) to create conditions for natural regeneration. Preferably, this should be undertaken in the year following the mast, when maximum seed is produced by the stand. An area adjacent to the gene reserve could be set aside for natural regeneration, and could later be incorporated as part of the reserve.
To promote regeneration in clear-cut strips, randomly selected, abundantly flowering seed trees should be left. If the population consists of some stands or groups of trees of different ages but there is no regeneration, the oldest stands or groups should be cut as soon as the mast years have produced sufficient seed yield or regeneration under the canopy or in areas set aside. Increasing the number of stands or demes (groups of trees) of different ages in the population enhances intra-population genetic variation as the portion of trees involved in regeneration increases. Regeneration can also be stimulated by site scarification and weed control. If these regeneration support measures are not successful, it is recommended that material originating from the population is planted: seed should be collected from at least 50 trees per population, preferably from central parts of the gene reserve. To prevent gene flow from outside the gene reserve, a buffer zone of 100- 150 m should be created by gradually removing mature flowering ash trees within this zone.
To secure the sustainability of each population, careful tending is required. Effective treatment including adequate silvicultural measures, protection against disease or insect outbreaks, fire or other factors must be undertaken promptly. Thinning should be undertaken from below, removing suppressed and injured trees, thus simulating and stimulating the natural selection processes in the forest, and stand regeneration. Each gene conservation population must be constantly monitored, including the health status and regeneration success.
For populations that are marginal, isolated, endangered, growing under special ecological conditions or carrying rare features, in situ conservation should be complemented by ex situ measures. The most effective form is through progeny trials, which permits joint gene conservation and breeding. On a national scale, 1-3 progeny plantations for conservation/breeding (each of 2-4 ha in size) should be established in each provenance region with entries sampled from single trees randomly chosen from 10- 20 stands within the region and from marginal populations if applicable. As soon as reproductive age is reached, open pollination of the best individuals selected within each family should ensure the next generation. About 50 optimally adapted individuals should be the founders of each new gene conservation/ breeding sub-population
Genetic conservation aims at ensuring continuous survival and adaptability of the target species. These objectives are met when the Multiple Population Breeding System (MPBS) is applied. Ideally in MPBS, a breeding population is subdivided into subpopulations which are then grown over a wide range of site conditions.
In each country where common ash is found, an inventory should...
Noble Hardwoods Network: Report of the sixth and seventh meeting
Noble Hardwoods Network: Report of the third meeting
Noble Hardwoods Network: Report of the first meeting
Noble Hardwood Network: Report on the fourth and fifth meeting
Contacts of experts
NA
Further reading
Hebel, I., Haas, R., and Dounavi, A. 2006. Genetic variation of common ash (Fraxinus excelsior L.) populations from provenance regions in southern Germany by using nuclear and chloroplast microsatellites. Silvae Genetica, 55(1): 38–43.
Heuertz, M., Hausman, J.F., Tsvetkov, I., Frascaria‐Lacoste, N., and Vekemans, X. 2001. Assessment of genetic structure within and among Bulgarian populations of the common ash (Fraxinus excelsior L.). Molecular Ecology, 10(7): 1615–1623.
References
Ballian, D., Monteleone, I., Ferrazzini, D., Kajba, D., and Belletti, P. 2008. Genetic characterization of common ash (Fraxinus excelsior L.) populations in Bosnia and Herzegovina. Periodicum Biologorum, 110(4): 323–328.
Dacasa Rüdinger, M.C., Glaeser, J., Hebel, I., and Dounavi, A. 2008. Genetic structures of common ash (Fraxinus excelsior) populations in Germany at sites differing in water regimes. Canadian Journal of Forest Research, 38(5): 1199–1210.
Ferrazzini, D., Monteleone, I., and Belletti, P. 2007. Genetic variability and divergence among Italian populations of common ash (Fraxinus excelsior L.). Annals of Forest Science, 64(2): 159–168.
Pliûra A. and Heuertz. M. 2003. EUFORGEN Technical Guidelines for genetic conservation and use for common ash (Fraxinus excelsior). Rome, International Plant Genetic Resources Institute. 6 pages.
Semizer-Cuming, D., Kjær, E.D., and Finkeldey, R. 2017. Gene flow of common ash (Fraxinus excelsior L.) in a fragmented landscape. PLoS One, 12(10): e0186757. https://doi.org/10.1371/journal.pone.0186757
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