Scots pine (Pinus sylvestris L.) morphological variation in the Massif Central region, France. : A study of differences in traits between populations.

Abstract: Scots Pine (P. sylvestris L.) has one of the largest distributions among trees in Eurasia. It is important both economically and ecologically, with a dominant role in forests ecosystems. Its distribution and survival may be affected by climate change as well as by abiotic and biotic factors. Therefore, it is important to conserve genetic diversity that can be of major importance for the species adaptation to future conditions. Relictual populations are of particular importance since they could display very rare traits. The aim of this study is to investigate if there are relictual populations in the Massif Central region of France, by determining if there are phenotypic differences between populations. This area has been highly planted with trees from “Germany” or “Riga” in the second half of the 19th century since the local trees had the reputation of not growing straight enough. We compared 100 Scots pines from 10 populations using five phenotypic traits (diameter of the trunk, shape of the trunk, crown, and branches along with the colour of the trunk and foliage). We detected phenotypic differences between populations that were independent from the diameter and elevation of the trees for three out of the five phenotypes (bark colour, shape of the stem and crown). However, the outstanding populations were never the same. It was therefore not possible to determine if a population was relictual or not based only on these phenotypic traits. In future studies, genetic data could give more information about the possible origins of each tree.