[COLLOQUE] GENTREE Final Conference 27-31 January 2020 séance 28

GENTREE Final Conference :

Devrim SEMIZER-CUMING - Forest Research Institute Freiburg · Germany

GENTREE Final Conference 'Genetics to the rescue - managing forests sustainably in a changing environment'

27-31 January 2020, Avignon, France

http://www.gentree-h2020.eu/

Devrim SEMIZER-CUMING - Forest Research Institute Freiburg · Germany: Genetic management of European ash (Fraxinus excelsior) forests inthe face of ash dieback through enrichment plantings

The emerging infectious pathogen Hymenoscyphus fraxineus has beendecimating common ash (Fraxinus excelsior) populations throughoutEurope for more than two decades.

This causes socio-economic lossesandecological problems as well as concerns over the future existenceof the species in European forest ecosystems.

Previous studies havereported heritable genetic variation in ash dieback susceptibility,suggesting that ash may possess genetic potential to recover in thelong run via natural selection.

Enrichment plantings with toleranttrees based on the offspring from selected and tested ash trees cansupport the recovery process by maintaining the species in the forestand allowing them to disperse their seeds and pollen.

However, theefficiency of such a strategy will depend on the reproductive fitnessof surviving trees and the extent of gene flow between planted andold trees.

We therefore investigated seed and pollen dispersal at twodifferent sites, Rösenbeck (Germany) and Valby Hegn (Denmark).

Wefurther tested the hypothesis that healthy tolerant trees have higherreproductive success than trees with high disease susceptibility inthe populations severely affected by ash dieback.

Here we used healthassessments combined with microsatellite data from a clonal trial atTuse Næs (Denmark) and the mixed continuous forest of Valby Hegn.

Wefound that ash trees had spread seeds and pollen several hundredmeters into the surrounding, managed forests.

We also found thathealthy trees had superior reproductive success. Our results suggestthat natural recovery can be supported by enrichment planting ofseedlings propagated from tolerant ash genotypes.

Human interventionmay therefore prove valuable to ensure the future existence of ash inEuropean forests when sound genetic principles are integrated intomanagement practices.