Faculty of Biology (1996) at Vytautas Magnus University (Bachelor's degree in Biology). Bachelor's thesis: "Dendroclimatological research of Norway spruce in Kazlų Rūda forests". A work, "Dendroclimatological research of Norway spruce in central and western Lithuania", in a competition of high school students organised by the Lithuanian Academy of Sciences was granted a diploma (1996). Master's diploma (1998) in Environmental protection organisation from the Department of Environmental Research. Master thesis: "Dendroclimatological research of Norway spruce in central and western Lithuania". Doctoral diploma (1998) from VMU Department of Environmental Research (Biomedical Sciences, Ecology and Environmental Sciences). The dissertation was maintained on 11th September of 2002: "Impact of climate factors to the radial increment of Norway spruce (Picea abies (L.) Karst.)". A. Vitas was awarded for the best results in the biomedical sciences in 2012 by VMU. A. Vitas is a member of the Tree-Ring Society.
4–9th July 1999. International dendroecological field week. Czech Republic, Baburek. Organisers: Prof. Dr Fritz Hans Schweingruber (University of Bazel, Switzerland) and Dr Monika Kroupova (Praha Forest Institute, the Czech Republic).
13–20th September 1999. Nordic Research Course in Dendrochronology and Dendroclimatology. Sweden, Backagården. Organisers: Dr Ólafur Eggertsson (the University of Lund, Department for Quaternary Geology, Laboratory of Tree-Ring Anatomy and Dendrochronology).