Fig. 2

The transitional ecotone from the European beech closed forest to the mountain pine krummholz vegetation in the Majella Massif. Diachronic analysis on aerial photos carried out in 1954, 1996, and 2017 originated from aerial images of the “Volo Base IGM 1954/56,” Geographical Military Institute (Italy), aerial images of “Volo Parco Scientifico e Tecnologico d'Abruzzo 1996” and 2017 available from WEB platforms at international level (Google Earth). Because environmental conditions change with increasing elevation, the variation in spatial patterns between beech forest and pine krummholz in the circular areas of 200 m in diameter marked in each site (with the center established between pine krummholz and beech forest) can be visually represented. The transition from beech forest (light color) to pine krummholz (dark color) is determined by changing growing conditions, resulting in in spatial separation between the two vegetation types