Distribution of Natura 2000 forest habitats in managed oak forest stands of south-western Poland

Pedunculate oak and sessile oak Quercus robur and Q. petraea are of significant economic impor- tance in Central Europe, but they are also species with an important ecological function. Therefore, forest management in oak forests should consider both timber production and environmental goals. The aim of the present study was to assess the occurrence of valuable Natura 2000 forest habitats in managed oak forest stands, the distribution and connectivity of their patches, and also the age of the oak stands. The analyses included forest stands with a dominance of native oak species located in SW Poland. Spatial analysis was performed with ArcGIS 10.7 software, and the age of trees was analysed with Statistica 12. In total, 66% of the area of managed oak stands was occupied by Natura 2000 habitats. The largest area was recorded for oak-hornbeam forests (9170), and the smallest for oak steppic woods (91I0). The area of Natura 2000 habitats was similar within and outside Special Areas of Conservation (SACs). The oak stands that did not represent Natura 2000 forest habitats had a larger area outside the SACs. Moreover, oak stands representing Natura 2000 forest habitats formed a greater number of forests larger than 5 ha. Oak stands not representing Natura 2000 forest habitats were more frag- mented and dispersed. The mean age of trees in oak stands was significantly higher for Natura 2000 habitats. Forest stands of most oak-hornbeam forests (9170), acidophilous oak forests (9190) and oak steppic woods (91I0) were older than 80 years. Riparian mixed forests (91F0) were more frequently represented by younger forest stands. The study revealed that the old-age oak stands which formed larger and more compact forests, mainly within SACs, were the most valuable within managed oak stands. These forest stands mostly represented Natura 2000 habitats. However, the coherence of the Natura 2000 network was also improved by the Natura 2000 habitats located outside SACs. As a result of forest stand logging and regeneration, patches of Natura 2000 habitats are expected to lose their specific structure and functions. Therefore, it is important to preserve at least fragments of old forest stands to facilitate the regeneration of the forest community. The ranges of Natura 2000 habitats should be designated based on the presence of model habitat patches and the surrounding vegetation representing dynamic phases of plant communities.

Automated summary

The study aims to assess the occurrence and distribution of Natura 2000 forest habitats in managed oak forests, as well as the age of the oak forests. The results show that Natura 2000 habitats occupy a significant portion of the managed oak forests, and older oak forests within SACs form larger and more compact forests.