Dendrometry and morphometry of Pinus pinea L. in Lower Provence (France):: adaptability and variability of provenances

The long-term over-exploitation of forests since ancient times is a specific aspect of the French Mediterranean region which has led to uncontrolled forest fires and landscape degradation. During the last century extensive reforestations were carried out throughout the region, but too often produced simplified ecosystems of fast growing species not always well suited to the environmental conditions. In this context, major programmes have been initiated in the study of native species suitable for afforestation in land reclamation and conservation. One of these species, Pinus pinea L., is particularly attractive from ecological, social and economic points of view. As a part of one of these larger projects, the aim of the present study is: (i) to evaluate P. pinea L. adaptive variability by comparing growth of genetically identified provenances in controlled environmental conditions, (ii) to distinguish some original discriminating characteristics and then, (iii) to determine the best genotype(s) for regional afforestations. In order to establish some criteria of early selection, we chose an experimental site in Lower Provence composed of 6-year-old planted seedlings. Comparisons of the 38 Circum-Mediterranean provenances planted on this site highlight better height growth for the Tunisian and most of the French provenances. Further dendrometrical and morphometrical analyses were thus carried out on two Provencal (French) provenances ("Le Val" and "St Raphael"). The results of comparative studies on growth of these two populations reveal more vigorous growth and better germination capacity for the provenance "Le Val" than for "St Raphael". However, the former provenance is sensitive to late frosts because of its early bud burst. These results are intended to guide forest managers in afforestation. Nevertheless, the influence of genetic factors is affected by site factors (percentage of outcropped pebbles, micro-topography) which mask the provenance effect. The present study provides meaningful insights into the early stages of P. pinea L. seedling establishment in newly planted Mediterranean forests after disturbance, and significantly improves the characterization of the two provenances studied. (C) 2004 Elsevier B.V. All rights reserved.