Unravelling collembolan life belowground: Stoichiometry, metabolism and release of carbon and nitrogen

This thesis investigated carbon and nitrogen dynamics of soil dwelling Collembola by using direct measurements and stable isotope additions. In an isotope change experiment, collembolans exchanged between 6 and 10 % of carbon and nitrogen in their body tissue per day to metabolism and between 0.5 and 2 % to reproduction. When collembolans on low and high protein diets were compared, animals on the low protein quality depleted their tissue N values relative to those on high quality diet indicating that the nitrogen turnover decreased on the low protein quality diet. In a wheat microcosm investigating source contributions from soil, roots and isotope labelled green manure the mixing model analysis indicated that photosynthate (root derived C) was the main carbon source for collembolans (54 – 79 % of total C) indicating that the rhizosphere channel is very important for collembolans in addition to the detri-