He is especially fascinated by benthic diatoms and other unicellular organisms and use them as model taxa to test general hypotheses in biogeography and community ecology. Janne employs meta-analyses as a tool to test broad generalizations in macroecology. His intention is also to examine species traits and ecosystem processes at large scales to contribute to recently established field of functional biogeography in aquatic ecosystems. Studies have regional to global covers and they relate to many spatially structured environmental drivers. Such research is useful when combating eutrophication of freshwaters or climate change.