This study aimed to investigate what kind of conceptions do the elementary pre-service teachers (EPT) have of the concepts: species identification (SI), biodiversity (BD) and sustainable development (SD) and how well they understand the relationships between these three concepts? The data of this survey has been collected in Finland and Sweden in 2011. The EPTs (186) were asked to describe the three concepts SI, BD and SD and their relationships. Special emphasis was given to use of e.g. mind maps or concept maps to explain the relationships. In inductive content based analysis EPTs´ understanding of the three concepts and their relationships were studied. The results show, firstly, the three concepts were connected to each other via EPTs´ knowledge or understanding, e.g. the importance of conserving the nature and the understanding of its function as well as man´s interest in the nature and understanding of the basic biological phenomena were emphasized as important matters necessary for comprehending the multifaceted concepts. Secondly, the concepts were connected to each other via man´s actions, e.g. when describing the relationships between the concepts man´s actions were repeatedly mentioned. Man´s action and the way of living have an effect on conservation of the BD. Furthermore, people benefit from BD and take this into account when evaluating the importance of SD. Thirdly, the relationships of the concepts was difficult to understand by the students. In this case the connections between the concepts were not identified at all or the connections were not clearly described. Especially the relationships between SI knowledge and BD or SD were difficult to understand.