This project received fundings from several fundings: The Monitech project funded by the Danish Council for Strategic Research, Wala och Folke Danielssons fond and Stiftelsen Oscar och Lili Lamms minne. I am grateful for the assistance from the technicians from the department of Bioscience, Erling Pedersen, Marlene V. Skjærbæk, Kathe Møgelvang and especially Dorte Nedergaard for the help with the gas measurements. Many thanks to my supervisors Carl C. Hoffmann and Joachim Audet, at the department of Bioscience, Aarhus University, Denmark. I would also like to thank my fellow students in Linköping and Silkeborg and to my family.