Populus nigra - EUFORGEN European forest genetic resources programme

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, 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).

Genetic diversity and variation

Black poplar populations in the centre of its distribution typically have high genetic diversity (Jiang et al., 2015), with 72%–90% of genetic variation within populations (Smulders et al., 2008). Marginal populations have been shown to have lower genetic diversity, with only about 9% of genetic diversity between populations, showing low genetic differentiation (Jiang et al., 2015). Planted populations of black poplar also have lower genetic diversity than natural populations (Jiang et al., 2015).

Hybridization and introgression of black poplar occurs with other genetically related species such as Canadian poplar (Populus canadensis) and eastern cottonwood (Populus deltoides), especially if trees are in close vicinity (Vanden Broeck, 2003; Rathmacher et al., 2010).

Genetic distribution and clustering

Populations of black poplar on the same river system that are geographically close are less genetically differentiated compared to populations on different river systems (Smulders et al., 2008). While there is greater differentiation between populations on different river systems, differentiation is still low due to long distance gene flow (Vanden Broeck, 2003; Smulders et al., 2008; Jiang et al., 2015).

Black poplar may have had three glacial refugia in Europe, and postglacial colonization routes are a strong influence on the current observed structure of the genetic diversity in black poplar (Jiang et al., 2015). Spanish and French populations are genetically distinct from one another, originating from different refugia (Smulders et al., 2008).

Gene flow

70% of gene flow in black poplar occurs within less than 1 km, creating spatial genetic patterns and small-scale isolation by distance (Rathmacher et al., 2010). Gene flow and mating also does not occur randomly, with female trees preferentially mating with a restricted number of males (Vanden Broeck, 2003). However, gene flow can still occur over large distance and between river catchments (Smulders et al., 2008).

Vegetative and clonal reproduction is also widespread in black poplar and has been shown to be highest along regulated rivers and in man-made populations (Smulders et al., 2008). For example, black poplar populations in Britain, Ireland and the Netherlands that have undergone human management have a high proportion of vegetatively propagated trees (up to 40%) (Smulders et al., 2008).

The bibliographic review was conducted by James Chaplin of the EUFORGEN Secretariat in August 2024.

No available information.

The bibliographic review was conducted by James Chaplin of the EUFORGEN Secretariat in August 2024.

Threats

Black poplar is one of the most threatened tree species in Europe as up to 99% of riparian forests in Europe have disappeared because of human activities (Smulders et al., 2008; Rathmacher et al., 2010). Riparian forests throughout the species’ distribution are under threat from changes in river systems and change in land use to agriculture and urbanization (Vanden Broeck, 2003). Flood regulation has affected regeneration, favouring the succession of poplar stands by hardwood forests (Vanden Broeck, 2003). Black poplar has been overexploited and faster-growing hybrid poplars have been planted to replace black poplar populations. Introgression from cultivated clones and other species also threatens black poplar genetic diversity (Vanden Broeck, 2003).

Management

Natural habitats and floodplain dynamics should be restored using seed from remaining populations to ensure sufficient natural regeneration and conservation of this species (Smulders et al., 2008; Rathmacher et al., 2010). When the goal is long-term gene conservation and maximizing adaptive potential, dynamic in situ conservation is preferable (Vanden Broeck, 2003). This can be achieved through in situ conservation and restoration of native stands and long-term breeding programmes (Vanden Broeck, 2003). Conservation units should be established throughout the range of the species and include more than one conservation site per river system (Vanden Broeck, 2003). Genetic diversity among adult trees should be assessed in candidate populations to ensure that a high amount of diversity and a low number of clonal duplicates are conserved (Vanden Broeck, 2003).

The bibliographic review was conducted by James Chaplin of the EUFORGEN Secretariat in August 2024.

As a general objective, the conservation of genetic resources should maintain the adaptation potential of species and populations. Static ex situ conservation is a widely applied strategy for short-term conservation to preserve genotypes in ex situ collections or genebanks. When the objective is long-term gene conservation and maximization of the adaptive potential of a species, dynamic in situ conservation is preferable. This can be achieved through in situ conservation of native stands (including restoration of stands), long-term breeding programmes or both. Successful in situ conservation of black poplar in Europe primarily depends on the location and protection of its natural habitats.

The conservation units should be distributed throughout the distribution range of the species, preferably including more than one conservation site per river system. A preliminary assessment of the genetic diversity among adult trees in the candidate populations is recommended to conserve a high amount of diversity and a low number of clonal duplicates. Particular attention must be paid to all practices that have an impact on flowering habit and the regeneration process, which determine the effective population size. Conditions for seed-set and seedling establishment should be optimized.

For restored populations, introgression can be limited by creating a “buffer zone” around the population consisting of local male trees. Active management and evaluation of the restored populations are highly recommended and should include replacement of poorly flowering individuals, corrective thinning, new additions to and from the genebanks, and removal of unsuitable individuals to avert the threat of introgression or poor adaptation.

P. nigra is a typical pioneer tree species of the riparian forest ecosystem. Therefore, the in situ gene conservation strategies and methods developed for other forest tree species are not always suitable. In fact, successful in situ conservation strategies for black poplar need to consider the current status and management of existing populations as well as the physical dynamics of the natural habitat formed by the river. Furthermore, conservation relies heavily on the potential to restore entire floodplain ecosystems, as well as the development of appropriate strategies for the management of restored sites. These factors not only determine the objectives of designated in situ conservation units, but also the methods and costs of the approach that is ultimately adopted.

This identification sheet was prepared by members of the EUFORGEN Populus nigra Network, in order to facilitate the simplest possible identification of the species from cultivated hybrids and possible introgressive forms. The morphological traits common to different species of the genus Populus are not referred to.

The drawings should be considered as having an indicative value in the field and can not represent strict taxonomic criteria. All illustrations were drawn by Mr Filip Coopman of the Institute for Forestry and Game Management in Geraardsbergen, Belgium. The original drawings were kindly provided as Belgium's contribution in kind to the Network.

This identification sheet is available in <link file:2963 _blank download file>English, <link file:2964 _blank download file>French, <link file:2966 _blank download file>Italian, <link file:2965 _blank download file>German, <link file:2962 _blank download file>Dutch and <link file:2967 _blank download file>Russian. Copies can be obtained from the EUFORGEN Secretariat.

Populus nigra
European black poplar

Environmental zones