Functional diversity of nitrogen transforming microbial communities during terrestrial ecosystem development.

In the present Ph.D. thesis, the succession of nitrogen cycle communities along the Damma glacier chronosequence was examined. Therefore, functional marker genes of nitrogen fixation, nitrogen mineralisation, nitrification and denitrification were quantified and correlated with potential enzyme activities in bulk soil samples being ice-free for 10-, 50-, 70-, 120- and > 2000-years. Moreover, the influence of pioneering plants like Leucanthemopsis alpina (L.) Heywood was investigated. Data indicates that the ecosystem development at the Damma glacier takes place in at least three phases. The bulk soil of initial sites is dominated by mineralising microbes. Nitrogen fixing communities are favoured in connection with plants and low nitrogen contents in the transient soils. Contrarily, after 120 years of development, when the vegetation cover is closed, processes like denitrification and nitrification are enhanced