Management of genetic resources of the multi-purpose tree species Castanea sativa Mill.

The general objective of the CASCADE project was to develop a strategy for long-term gene conservation and management of European Chestnut. The distribution area of chestnut was described by climate and edaphic conditions. Eighty-two populations, naturalised – coppice – fruit orchards, were analysed with respect to genetic markers to describe diversity and gene flow. Six naturalised populations from a broad span of climate conditions were included in studies of early growth, drought tolerance, and tolerance against Phytophtora cambivora. Six field trials were established. To identify the socio-economic impact of commodities from chestnut forests and orchards enquiries were distributed to regions, in which chestnut plays a role in the local economy. It was noted that chestnut is demanding with respect to edaphic conditions. A xerothermic index considering precipitation and mean temperature during the growth period was developed. European chestnut stands retain a fairly large amount of marker-based genetic variation. The effective number of alleles is fairly abundant in southern European regions, decreasing toward north and west. Mating probability dropped below 0.01 for distances larger than 2 km, and increased up to about 10% for distances closer than 300 meters according to the gene flow study. Genetic variability among and within populations was observed for juvenile growth, phenology, carbon isotope discrimination, and Phythophtora cambivora susceptibility. The latter variability was lower between domestication levels than within populations. Based on an inventory a distribution map for different Phytophthora species was provided. The enquiries disclosed that restoration of high forests was a top-ranked preference and so was the willingness to pay. Based on the data collected conservation values were derived for adaptive traits and markers. One suggestion for gene conservation was developed in the form of a network of gene resource populations covering the different climatic conditions of the sweet chestnut distribution area.