Interest: All aspects of geobotany and phytosociology of the North, especially the Arctic with Greenland; lichenology and bryology pertaining to vegetation; vegetation classification, syntaxonomy; plant community dynamics, global change, mapping, monitoring and nature conservation. See also Bültmann-H, Pallas-J, Schmidt-C & Sieg-B (2008): Aspekte der Geobotanik-From Local to Global. Eine Festschrift für Fred Daniëls.  Abh. Westf. Mus. Naturk. 70 (3/4): 1-492.

Research areas: Expeditions and fieldwork in the circumpolar North including Greenland (15), Alaska with Aleutian Islands (2), Arctic Canada (3), Iceland (4), Faroe  Islands (1), Arctic and Boreal East Siberia (1), Scandinavia (6), Western Europe (>15), European Russia with Ural (3), Kazakhstan (1), Egypt (1), Canary Islands (2), S Africa (1), and the desert states (1) and Mid-west (1) of the US.
Projects: Vegetation classification of Greenland; Vegetation of Greenland (book project); CBVM (Circumboreal Vegetation Map), EVS (European Vegetation Survey Project of the IAVS (International Association of Vegetation Science) and AVA (Arctic Vegetation Archive); Global change of lichen vegetation.
Collaborations: Alaska Geobotany Center, UAF, Fairbanks (Prof. Dr. DA Walker), US Fish and Wildlife Service, Anchorage (Dr. SS Talbot), Komarov Botanical Institute, St. Petersburg, Russia (Dr. N. Matveyeva), Dr. H Bültmann, Münster, Dr. JG de Molenaar, Maurik, NL; Prof. Dr. D. Thannheiser, Hamburg, Prof. Dr. M.J.A. Werger, Utrecht, NL and Prof. Dr. R Pott, Hannover and CFG (Flora and Vegetation Group) of the CAFF (Conservation of Arctic Flora and Fauna, Akureyri, Iceland. Memberships of editorial boards: Phytocoenologia, Acta Phytogeographica Suecica, Tuexenia and Berichte der Reinhold-Tüxen Gesellschaft.