Effects of sieving, drying and rewetting upon soil bacterial community structure and respiration rates.
Soil microcosm studies often require some form of soil homogenisation, such as sieving, to provide a representative sample. Frequently, soils are also homogenised following drying and are then rewetted, yet little research has been done to understand how these methods impact upon microbial communities. Here we compared the molecular diversity and functional responses of intact cores from a Scottish grassland soil with homogenised samples prepared by drying, sieving and rewetting or freshly sieving wet soils. Results showed that there was no significant difference in total soil CO(2)-C efflux between the freshly sieved and intact core treatments, however, respiration was significantly higher in the dried and rewetted microcosms. Molecular fingerprinting (T-RFLP) of bacterial communities at two different time-points showed that both homogenisation methods significantly altered bacterial community structure with the largest differences being observed after drying and rewetting. Assessments of responsive taxa in each treatment showed that intact cores were dominated by Acidobacterial peaks whereas an increased relative abundance of Alphaproteobacterial terminal restriction fragments were apparent in both homogenised treatments. However, the shift in community structure was not as large in the freshly sieved soil. Our findings suggest that if soil homogenisation must be performed, then fresh sieving of wet soil is preferable to drying and rewetting in approximating the bacterial diversity and functioning of intact cores.
Thomson
Bruce C
BC
Centre for Ecology Hydrology, Maclean Building, Benson Lane, Crowmarsh Gifford, Wallingford, OX10 8BB, United Kingdom. brth@ceh.ac.uk
Ostle
Nick J
NJ
McNamara
Niall P
NP
Whiteley
Andrew S
AS
Griffiths
Robert I
RI
D001419:Bacteria / Q000235:genetics / Q000302:isolation & purification / Q000378:metabolism*; D044822:Biodiversity; D002245:Carbon Dioxide / Q000378:metabolism; D008828:Microbiological Techniques / Q000379:methods*; D012987:Soil / Q000737:chemistry*; D012988:Soil Microbiology
D012987:Soil; D002245:Carbon Dioxide