Liis Kasari will defend her doctoral thesis titled "Plant diversity of semi-natural grasslands: drivers, current status and conservation challenges" on 15 Septembr at 10.15.
Senior Research Fellow Aveliina Helm, University of Tartu, Institute Ecology and Earth Science
Professor Vigdis Vandvik, PhD, University of Bergen (Norway)
Description of the problem
Semi-natural grasslands harbour a large part of Europe’s biodiversity and hold the records for highest small-scale (e.g. 10x10 cm) plant species richness in the world. During the past century, ca. 90% of the grassland area has been lost due to the urbanization, intensification of agriculture and cessation of traditional management, rendering many species vulnerable to local extinctions. Habitat restoration and conservation, based on the ecological theories, is needed for successful biodiversity protection. The thesis covered the shortcomings in the knowledge of which factors determine the high plant species richness in semi-natural dry calcareous grasslands. She also assessed the status of dry to mesic grasslands in central and northern Europe, and provided implications for biodiversity restoration and conservation of communities with different level of degradation.
Result and benefit
Author found that species richness is dependent on historical habitat area and connectivity as well as suitable local environmental conditions, indicating the importance of considering both landscape- and local-scale factors in habitat restoration and conservation. In six studied regions in central and northern Europe, specialist species susceptible to habitat loss have gone already extinct and communities consisted more habitat generalists. Remaining specialists appeared to have considerably lower dispersal ability. In four regions, specialist species still temporally persist despite of the unfavourable habitat conditions. Habitat restoration is urgently needed in those regions, to prevent the loss of good dispersers and infiltration of generalist species. In grassland systems where the habitat quality has considerably decreased and susceptible species have gone already extinct, complete restoration to historical state may not be successful. Therefore, instead of attempting their restoration to historical state or continuing their abandonment, it would be perhaps worthwhile to consider managing and maintaining such habitats as hybrid or novel ecosystems (i.e. habitats out of their historical range) as they are often still species-rich and can contribute to the local biodiversity protection. However, the priority must be set to restoration and preservation of historically developed habitat types.