Variation of morphological needle characters of Scots pine (Pinus sylvestris L.) populations in different habitats

We investigated the phenotypic variation of five morphological needle characters of Scots pine (Pinus sylvestris L.) in three populations. Two of the populations occurred in bogs and the third one formed a degraded fresh pine forest showing some features of a dry pine forest. The greatest variation was found in characters a (needle length), b and d, denoting the number of stomatal rows respectively on the convex and flat sides of the needle. Conversely, characters c and e (average number of stomata per 2 mm of needle length on the convex and the flat side of the needle) were stable, with little interindividual variation. The two bog populations and the dryland population exhibited different sets of character correlations. The interpopulation differentiational detected on the basis of morphological character expression was markedly influenced by both the different edaphic conditions, and the distinct genetic structure of the studied populations.