Ancient burial mounds – biodiversity hotspots and refugees for natural flora and vegetation

Bulgaria is enormously rich in historical monuments. Burial mounds are one of the most numerous among them. They are spread all over the country but are localized in lowlands where active agriculture takes place. Patches of semi-natural vegetation are often preserved on the ancient burial mounds most of which are remnants from thousands years ago. The burial mounds which are generally surrounded by vast agricultural fields of monocultures often host the remnants of autochthonous flora. Besides being hotspots for biodiversity preservation, the ancient burial mounds are ideal objects for testing the theory of island biogeography. In our study we selected 577 mounds distributed near equally in northern and southern Bulgaria. Around each one mound a buffer of 200 m was outlined and the land use types were mapped aiming to identify the influence of land use on the floristic diversity. Our methodology includes sampling all vascular plants and their abundance within two sample plots of 25 m 2 positioned in the middle of north and south facing slopes. The scientific goal of our research is to reveal the significance of the burial mounds not only as cultural value, but also as natural treasure for the country. This would additionally emphasise their attraction as touristic objects.