International Journal of Research Studies in Biosciences (IJRSB) Volume 4, Issue 1, January 2016, PP 38-51 ISSN 2349-0357 (Print) & ISSN 2349-0365 (Online) http://dx.doi.org/10.20431/2349-0365.0401008 www.arcjournals.org ©ARC Page | 38 Biodiversity of Relict Vascular Plants in Bulgaria Dimcho Zahariev Faculty of Natural Sciences, University of Shumen Bishop Konstantin Preslavski 115 Universitetska Str., 9712 Shumen, Bulgaria dimtchoz@abv.bg Abstract: Climate changes observed in the last years pose a serious threat to biodiversity. Similar climatic changes, nevertheless, have occurred many times in our planet’s history. Relict plants that survived after experiencing climate change can give us information about the past and the future of species. The rich biodiversity in the countries of Southern Europe, including Bulgaria, is shaped by a large number of relict plants. To date, the biodiversity of relict plants in Bulgaria has not been systematically described and remains somewhat unknown. Our aim is to systematize available information and present biodiversity of relict vascular plants in Bulgaria. Using a critical approach, we discovered 346 species of 207 genera and 81 families of relict origin. This number accounts for 8.74% of the natural flora of Bulgaria and 8.43% of the total flora of Bulgaria (which includes foreign species). We divided relict plants into two groups: tertiary relicts (183 species) and quaternary relicts (163 species). The quaternary relicts we divided into 3 groups: glacial relicts (143 species), interglacial relicts (13 species) and postglacial relicts (7 species). Among the relicts with the largest number are perennial herbaceous plants, followed by shrubs and trees. 144 relict species have conservation status. Keywords: relict, vascular plants, tertiary, quaternary, glacial, interglacial, postglacial 1. INTRODUCTION One problem of a global scale today is the loss of species and the rapid impoverishment of ecosystems. Paleontology has sufficient evidence that the extinction of species and even of large taxonomic groups has occurred throughout the history of our Earth. However, we should not remain calm in the face of the facts. In the geological past, these processes were caused by natural changes in the landscape, the atmosphere, and the climate. Today, a large number species is endangered by the expansion of human activity. While current and past changes are comparable in their scale, the speed of the changes that take place accelerates. The solution of this problem should be found in the joint efforts of experts from all fields of human knowledge and the economy. One way for biologists to effectively contribute to solving the problem is by focusing their research on relicts. To this end, it is important for us to study the origin, the history and the current condition of relicts. The term "relict" was introduced to Biology (in particular to Zoology) by Lovén [1] to explain findings of marine-type mysid crustaceans in freshwater lakes. The ecological and geographical criteria of recent relicts were analyzed in detail by Birshstein [2]. According to this author, those taxa that have remained almost unchanged in time (or are characterized by a delayed rate of evolution) are considered relict taxa. Vulf [3] defines "relict species" as remnants of more or less ancient flora, which occupied a relict area. The relict area is a remnant of a larger area, which was formed under specific conditions in the past different from those of other areas. In this sense, the term "relict species" is a historical-geographical concept, associated with the historical range of the species. The age of the relicts is determined by the time when the species has become a part of the flora composition. The origin and distribution of relicts can often be linked to past changes in their environment, in particular climate changes. Therefore, they can be called "climate relicts". The status of a species as climate relict is usually determined on biogeographical basis, using current geographical distribution and attachment to specific habitats. Most often climate relicts were separated into three groups: 1. Tertiary relicts that withdrew with the onset of drier and cooler climatic conditions during the late Tertiary and early Quaternary; 2. Glacial relicts that are more widely distributed during Quaternary cold stages and have experienced significant range contractions since the LGM; 3. Postglacial relicts that have survived to this day in regions with warmer climates, such as in the early Holocene [4].