On 13 Septembet at 10:15 Mari-Liis Viljur will defend her doctoral thesis „Local and landscape effects on butterfly assemblages in managed forests”.
Senior Research Fellow of Entomology Tiit Teder, Institute of Ecology and Earth Sciences, University of Tartu
Associate Professor Erik Öckinger, Swedish University of Agricultural Sciences, Rootsi
Decrease of biodiversity is a global problem mainly caused by loss of natural and semi-natural habitats. Local diversity is also affected by surrounding landscape: isolation of habitats leads to decline of species richness. Despite being important, protected areas alone may be insufficient to maintain biodiversity. The focus is shifting towards sustaining and enhancing species diversity in landscapes of significant human impact. Intensification of forest management due to increasing demand for timber, poses a threat for many forest species. However, some species may find favourable habitat in managed forests. The results of this thesis indicate that forest butterflies are among those. At caterpillar stage, forest butterflies feed on trees, bushes and understorey plants, whereas adults find nectar plants from clear-cuts. Therefore, the whole mosaic of managed forest landscape is important for forest butterflies. Indeed, I found higher species richness of forest butterflies in clear-cuts containing higher proportion of woodland in the surrounding landscape. Furthermore, my thesis shows that managed forest landscape containing various open habitats is also suitable for many open-habitat species. I found that clear-cuts serve as habitats for the majority of regional species pool of butterflies traditionally associated with semi-natural grasslands. Moreover, grassland species reach even to clear-cuts completely surrounded with forest, which implies that forest is not a significant barrier for colonisation. Assemblages of grassland species and forest species are both affected by local environmental conditions of forest: different forest types provide habitat for distinct butterfly assemblages. The diversity of forest types is therefore important for maintaining species richness of butterflies, as different forest habitat types complement each other.