Paweł Horodecki

Natural forest remnants as refugia for bryophyte diversity in a transformed mountain river valley landscape

Riparian forests are among the most threatened ecosystem types worldwide. Their exploitation and replacement by coniferous plantations affects species pools and contributes to loss of biodiversity. We aimed to investigate bryophyte species pools within different habitat types in a transformed mountain river valley. We especially focused on the contribution of habitat types (relative to their proportional cover) to the species pool of the whole area. The study was conducted along the Czerwona Woda river - a model stream in the Stołowe Mountains National Park (SW Poland, study area: 91.2 ha) - and an example of coniferous plantations replacing natural broadleaved forest vegetation. Our study revealed the presence of 147 bryophyte species. The most valuable habitats in terms of diversity of bryophyte assemblages were remnants of the natural vegetation - broadleaved forests and streams. These habitats, constituting <5% of the study area, hosted ca 40% of the total species pool (61 and 62 species, respectively), while the species pool of Picea abies forests (92 species) was proportional to cover of this habitat type (ca 60%). Remnants of natural vegetation were hotspots of bryophyte diversity within the heavily altered landscape, and may play a future role as sources of recolonization by forest specialists. Our study also confirmed the important role of riparian areas in maintaining bryophyte species diversity at the landscape scale. The river valley studied contributes >20-fold more to the bryophyte species pool of the whole national park than indicated by its size. Thus, river valleys require special treatment - conservation based on natural restoration, and should remain reserved from wood production, as areas providing a wide range of ecosystem services.

Natural regeneration in the ‘Czmoń’ nature reserve (Wielkopolska Region)

Abstract The ‘Czmoń’ nature reserve (23.65 ha) was established in 1998 to protect one of the best-retained areas of natural oak-hornbeam forest (Galio-Carpinetum) in the center of the Wielkopolska Region. Apart from oak-hornbeam forest, the ash-elm riparian forest (Querco-Ulmetum) and alder riparian forest (Fraxino-Alnetum) are found in the reserve. These plant communities, both natural and degenerated as a consequence of previous forest management, have created the convenient conditions for assessment the phytocoenoses’ regeneration potential. The aim of this study was to assess the age and species structure of woody species natural regeneration of the whole area of the nature reserve. To achieve that target, during August and September 2012, 142 sample plots were established with the total area 3550 m2 on which tree and shrub composition and densities were calculated. Woody species regeneration created various diverse communities among individual sub-units, however oak-hornbeam forest species were predominant in the whole regeneration layer. The character of a ‘natural’ forest was retained on a part of the stands. Moreover, regeneration in degenerated parts of the ‘Czmoń’ nature reserve stands is changing according to potential vegetation. Whereas, the establishment of gaps in the Scots pine stands using artificial regeneration was not worthwhile. The natural regeneration structure under the canopy layer of Scots pine stands unambiguously supports the claim that phytocoenoses can regenerate on their own. In spite of the oak regeneration being infrequent, all stands within the ‘Czmoń’ nature reserve retain substantial rejuvenation potential

Response of soil mites (Acari, Mesostigmata) to long-term Norway spruce plantation along a mountain stream

During the nineteenth and twentieth centuries, coniferous monocultures were introduced, replacing natural broadleaved forests in Central Europe, mainly for economic benefits. In the mountains, Norway spruce [Picea abies (L.) H. Karst] was introduced in large areas previously covered with beech forests and also in natural riverside habitat corridors such as river valleys, despite its negative impact on the soil environment by e.g. organic matter accumulation, decrease of soil pH and changes in C/N ratio. We aimed to check how long-term Norway spruce plantations affect species richness and diversity of soil mites along a mountain river in former mixed and broadleaved forests. The study, based on 342 samples, was carried out in Stołowe Mountains National Park (SW Poland). Understory species biomass, soil pH and soil organic layer thickness significantly affected soil mite communities. Although coniferous forests did not differ from either broadleaved or mixed forests in mite density (number of individuals m−2) and species diversity (H′), they were characterized by low species richness and proportional abundance of Uropodina mites typical for broadleaved forests. In total, 4849 mites classified into 57 species were recorded from all forest types and no unique species were found in the sampled forests. Although the mite communities were dominated by the same common species (Veigaia nemorensis, Paragamasus runcatellus, Leptogamasus obesus and Trachytes aegrota), they still maintain the rare species of broadleaved forests and their high recovery potential may be used in forest conversion.