Variabilità genetica e differenziazione tra popolazioni alpine e collinari di pino silvestre in Piemonte

We evaluated was the evaluation of genetic differentiation within and among populations of Scots pine (Pinus sylvestris L.) from the Alps and internal hills in Piedmont (North-Western Italy), in order to define the most appropriate procedures for in situ conservation of genetic variability. Scots pine is broadly widespread in Piedmont, although in a fragmentary way: most of the stands are located in the Alps and only few populations still survive in the internal, hilly areas of the region. Protection of these relict populations, threatened by competition with other species and lack of appropriate sylvicultural procedures, is of primary importance, to preserve biodiversity of the species and to maintain rural landscape. Samples of 8 native populations, representing the locations where the species grows in Piedmont, were collected and genetic diversity and differentiation were estimated using 16 enzyme loci. Populations from the Alps showed higher heterozygosity than populations from the hills, with the exception of the population sampled in Passerano Marmorito (Asti province), in which the highest value of expected heterozygosity was scored. Fixation indices were around zero, with the exception of Passerano Marmorito population, where a high value of 0.137 was found, evidence of a homozygote excess. Genetic differentiation among populations was 0.064. Genetic distance data allowed us to clearly distinguish alpine populations from internal ones, although the Passerano Marmorito stand showed peculiar characteristics. The latter appears therefore to be an important centre of genetic biodiversity: some suggestion for its management are briefly discussed.