I work on classification and phylogeny of basidiomycetes (Basidiomycota, Fungi). I try to bring sense in the diversity of polypores and corticioid fungi at various levels: describe new species, revise generic concepts, and construct higher-level phylogeny, i.e. evolutionary relationships of the species translated into a family tree. I'm also interested in the evolution of wood rot capability in basidiomycetes, and for this end involved in over 20 whole-genome sequencing projects of basidiomycetes.

Fungal diversity is still poorly known - an estimated 2% of the 5 million estimated species of fungi have been described to science. New species of polypores and corticioid fungi are found annually even in the relatively well-studied area of Nordic countries, and I have been involved in describing several of them. In the tropics, such as my research area Indonesia, most of the species are undescribed and many of the species have no close relatives in temperate areas.