The role of biosemiotic processes in the ecosystem biodiversity: how to study it? Kalevi Kull, Donald Favareau In the first issue of the journal Biosemiotics that we established with a group of biosemioticians in 2008, we formulated a series of research questions for biosemiotics (Kull, Emmeche, Favareau 2008). Sixteen years have passed, and in our presentation we will critically review how the work on these problems has developed. The problems were divided into five groups:(a) ways to distinguish between semiotic and non-semiotic life science; (b) problems concerning the biosemiotics of organisms’ experience and distinctions in umwelten;(c) problems concerning the biosemiotics of biological function;(d) problems concerning the attributes and boundary levels of biosemiosis;(e) biosemiotic case studies and design of biosemiotic experiments. In our presentation we will focus on the following problem: To what extent are biosemiotic processes responsible for ecosystem diversity? We will discuss the operationalization of this research question, the concrete ways to study it, its relatedness to (a–e), the possibility to formulate it in mathematical terms, and the methods to be used for testing the results.We expect to raise a discussion about biological effects that have biosemiotic explanation. References Kull, Kalevi; Emmeche, Claus; Favareau, Donald 2008. Biosemiotic questions. Biosemiotics 1(1): 41–55. Kull, Kalevi 2020. Scientific results in biosemiotics: Then and now. In: Lacková, Ľudmila; Rodríguez H., Claudio J.; Kull, Kalevi (eds.), Gatherings in Biosemiotics XX. (Tartu Semiotics Library 20.) Tartu: University of Tartu Press, 98–111.