Servizio Comunitario di Informazione in materia di Ricerca e Sviluppo - CORDIS

Establishment of a pan-European provenance trial of common ash (Fraxinus excelsior) in Flanders (Belgium) - First results

Forest policy in Flanders strongly promotes the use of indigenous hardwoods for re- and afforestation and for stand conversion. For common ash, this option is even more motivated by the acknowledgement of its high sylvicultural, ecological and economical importance. Furthermore, the species is often mentioned as a potential alternative for poplar in view of the afforestation of abandoned farmland.

This line of policy generates a strong demand for high quality forest reproductive material, which cannot be met by the currently available native basic material. In order to remedy the discrepancy between supply of and demand for reproductive material, large amounts of seeds are imported from foreign seed sources. Up till now, very little is known about the adaptiveness of these non-indigenous provenances, entailing the risk of genetic pollution of endemic populations.

Provenance testing aims at the assessment of the suitability and fitness of non-indigenous seed sources with respect to local growth conditions, thus meeting the urgent need for a List of Recommended Provenances for the benefit of private nurseries and public as well as private forest owners. Within the scope of the RAP-project, an international provenance trial was established in the field in autumn 2004, comprising a 'core collection' of 32 provenances, common to all partners involved, supplemented with 18 provenances of proper interest. A second, identical trial will be planted in autumn 2005.

First results are based on the assessment in the nursery of height growth and flushing. As regards height growth, no solid recommendations can be made regarding the best performing provenances in this developmental stage. Data are indeed strongly biased by the quality of the seeds exchanged (collection at different stages of development, different conditions of storing and stratification, conditions during transport) and by the quality of the plants exchanged (different nursery conditions, conditions during transport).

Flushing was recorded in spring 2003 and 2004. High congruence of flushing data was found between both moments of observation (rank order correlation coefficient = 0.87). Based on an overall analysis of the flushing data provided by the other partners involved, 'unstable' provenances (i.e. showing a high interaction with the planting site) were identified. These provenances were discarded when drawing the preliminary conclusions: northern and western provenances are late flushing (IRL, UK, LT, DK, southern and eastern provenances are early flushing (I, CZ), 'intermediate' provenances are located in Belgium, France and Germany. The 'odd ones out' are Kaisiadorys (LT) being early flushing and Sila Grande (I) being late flushing.

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