Göransson (Bangor University, United Kingdom), Harry Olde Venterink & Erland
"Bacterial growth limitation during primary succession in the Alps"
stages of primary succession there are only small amounts of C and N
available for bacteria and plants. In this study we investigated which
factor (C, N or P) limits bacterial growth along a 138 year long
chronosequence formed by a glacier retreat. This was done by adding labile
sources of C, N and P to soil samples and measuring the bacterial growth
response (Leucine incorporation) after a 40 h incubation period. The
bacteria were never found to be limited by N or P. On the youngest soils nor
C, N or P induced a bacterial growth which indicate co-limitation. On older
soils the bacteria was found to be C-limited. The shift from where the
bacteria did not respond to C to being C-limited was related to the C:N
ratio in the soil where the C-limitation occurring only on soils with a C:N
ratio below 13.4 (w/w). The increase in growth response to C addition with
increasing soil age suggests that N becomes relatively more available to
bacteria as compared to C as the soil develops.