Effect of land abandonment on the vegetation of upland semi-natural grasslands in the Western Balkan Mts., Bulgaria

Abstract

The area of semi-natural grasslands in Bulgaria has decreased tremendously in the past century due to agricultural intensification or abandonment. As these grasslands host valuable biodiversity, conservation measures are needed for their sustainable maintenance. We studied the effect of pastureland abandonment on plant communities at the Ponor Mt., a part of the Balkan Mts., Bulgaria. Data on floristic composition, vegetation structure and several abiotic parameters were collected in 137 randomly located 16-m² plots in 2008. Canonical correspondence analysis (CCA) was used to analyse how species composition is related to abiotic and land use factors. Analyses of covariance (ANCOVAs) were used to test for the effects of sheep grazing vs. abandonment on vegetation structure and composition. The main environmental factors explaining the compositional variation were related to the altitude, sheep grazing and soil depth. Pastureland abandonment led to an increase in vegetation height and of the richness of mesophytes and leafy plants, and red-list species. Grazed plots had higher total species richness, more xerophytes, rosette forming and spring-flowering species. To ensure the persistence of the species of both the open grasslands and mid-successional grassland communities, the management should be carried out in an extensive way and with a zonation regime.

Keywords:

• Festuco-Brometea
• pasture
• Ponor Mt.
• sheep grazing
• species composition
• species richness

Acknowledgements

K.V. and H.P. carried out the field data sampling and drafted a first version of the text together with S.C.N. Statistical analyses were carried out by S.C.N. and J.D. All authors critically revised the whole manuscript. This study was initiated and funded by the project “Conservation of globally important biodiversity in high nature value semi-natural grasslands through support for the traditional local economy” (UNDP project No. 43595 and GEF ID 2730), co-ordinated by the Bulgarian Society for the Protection of Birds/BirdLife Bulgaria. Georgi Popgeorgiev provided the digital maps of the area. The authors are grateful to the Alfred-Toepfer-Akademie für Naturschutz (NNA) and Deutsche Bundesstiftung Umwelt (DBU) for organising and financing an internship of H.P. with J.D. as part of NatuRegio project, where initial analyses were carried out. Finally, the authors are indebted to Mitzi DeVille (Lancaster) for checking the language of the manuscript and to Kathrin Kiehl as well as two anonymous reviewers for constructive suggestions on the first version of the manuscript.