The thesis approaches the concept of urban biodiversity from different angles in an attempt to explain its significance. In a study from the constructed Toftanäs wetland park, methods of affecting local biodi-versity are demonstrated as integrated with other functions, such as water quality and stormwater detention. Vegetation analyses are provided to show the rapid and sometimes unexpected change in species composition. Both spontaneous and introduced species were followed in a five-year project. Theoretical aspects of urban biodiversity are studied in-depth and the different views on biodiversity in general and urban biodiversity in particular are scrutinised. It is concluded that a holistic view on urban biodiversity probably reflects the true conditions best. In a method study, a few different kinds of biodiversity mapping were tested. It was con-cluded that the biotope-mapping model tested was easy and rapid, but incomplete. Patch mapping was more time-consuming, but possibly more informative. Patch shape was com-pared to species diversity, but there was no correlation. It was concluded that both kinds of mapping need to be calibrated with biological data, and that the human function of urban environments should be an integrated part of urban biodiversity studies. A method of assessing the perception of biodiversity was tested using a semantic test on-site. An index for biodiversity experience was created and later tested also in a photo-based study. Both studies comprised laymen as well as experts. It was concluded that there were differences between photo-based and on-site ratings, but the biggest difference was detected with the on-site experts. As a general conclusion of the thesis it can be stated that urban biodiversity is an integral part of the urban environment, and that it is impossible to regard the city without its bio-logical component, as well as it is impossible to regard the biological component without its human connection
