Comparative autoecological study of Pinus nigra Arn. ssp. salzmannii in the Iberian peninsula and other subspecies of the circun.mediterranean region

The ecological significance of mediterranean pine forests and their status as native plants are controversial questions which have resulted in much misinterpretation and ignorance of their role within plant communities. The concept of climax community is of little use in the mediterranean region, and should be abandoned in favor of a more dynamic view of the processes which influence vegetation structure. Pinus nigra serves as a good example, given its importance in mountainous areas throughout the mediterranean region where its various subspecies are found. Among these distinct subspecies, great adaptive similarities may be observed in comparative phytoecological analysis. The autoecological features of Iberian subspecies have been defined after an extensive field survey recording climatic, edaphic, vegetational, and silvicultural data throughout its distributional range. The central distribution nucleus has been more intensively surveyed in order to study in greater depth the dynamics of the Pinus nigra community and its role in succession. Comparisons with other subspecies throughout the mediterranean region have been made, particularly with the ecologically more similar ones (Subsp. laricio , subsp. pallasian a and subsp. dalmatica ). This species defines potential forest stands under suitable climatic conditions at both extremes of the mediterranean region (Greece/Turkey and the Iberian Peninsula). It also occupies sites of extreme severity both geomorphologically (rocky outcrops and steep slopes) and lithologically (dolomites, serpentines, etc.), where it may sometimes play an important edaphogenetic role. Our results showed more than 50 p. 100 of low developed soils (Rendzinas). In addition, it forms secondary pine stands which have expanded their range due to human activity. Pinewoods consisting of different subspecies show quite similar understories. Nevertheless, it is possible to define two community types: a) Submediterranean: with abundant deciduous species, but under drier environmental conditions than the marescent communities. b) Stepic cold mediterranean: with a cushion scrub appearing mainly in eastern and western regions, occupying even the highest mountainous forest belts. The intense biogeomorphological dynamism of these mountainous areas causes constant natural modifications, defining a mosaic of communities in which Pinus nigra has a great ecological importance.