25th International Meeting on Organic Geochemistry IMOG 2011

P-423
Effects of long-term climatic manipulations on microbial
communities in European shrublands
Sharon Mason 1 , Chiara Cerli 1 , Andrew Smith 2 , Albert Tietema 1
1 University of Amsterdam, Amsterdam, Netherlands, 2 Centre for Ecology and Hydrology, Bangor, United
Kingdom (corresponding author:s.l.mason@uva.nl)
Soil microbial communities are key regulators of soil
organic matter (SOM) dynamics. Therefore, shifts in
microbial community composition in response to
environmental change may significantly affect key
ecosystem processes, such as nutrient cycling and
soil organic carbon (SOC) turnover. Previous studies
have shown significant, yet contrasting microbial
response to increased soil temperature and altered
precipitation patterns [1, 2 & 3], highlighting the need
for a greater understanding of how different
ecosystems respond to such changes.
Climate change effects on European shrublands have
been investigated for more than 10 years during the
EU-funded projects of CLIMOOR (1998-2000),
VULCAN (2001-2004) and INCREASE (2009-2012),
with continued measurements at many sites in the
intervening years. A network of 6 large scale field
experiments simulate realistic levels of climatic
change in 20 m 2 plots, that are superimposed across
a natural temperature and precipitation gradient (Fig.
1). Each site has 9 experimental plots; 3 x control, 3
x warming and 3 x drought. Warming treatment is
achieved by covering plots with a reflective curtain at
night to prevent heat loss (increases soil temperature
by 0.4-1.2 ºC), whilst drought treatment is simulated
by covering plots with a transparent cover for 1-2
months during the growing season (Fig. 2). How the
different sites respond to climatic manipulation is most
intriguing, with findings indicating that the effect of
warming might be seen across all sites, whilst the
effect of drought could be more significant in Northern
as opposed to the drier Southern European soils [4].
Significant effects on soil processes have been found
but a greater understanding of molecular level
response is still required. In this study we assess and
report changes in phospholipid fatty acid (PLFA)
profiles to determine how microbial communities are
affected by climatic manipulations imposed across
experimental sites. Soil samples were collected from
plots in The Netherlands, Denmark, Italy, Hungary
and Wales (UK) in November 2009 and analysed for
PLFA content and composition using a modification of
the method outlined in [5]. We hypothesised that
warming would increase fungal:bacterial ratios, whilst
drought would reduce fungal community composition.
An initial assessment of outside plot samples showed
variation between sites in both total active microbial
biomass and fungal:bacterial ratios due to natural
differences between ecosystems. Linking these
findings with further molecular geochemical
assessment and investigation of microbial activity will
in future be critical to our overall understanding of the
shrubland ecosystem response to climate change.
Fig. 1. Location of infrastructures, showing natural gradients
in temperature and precipitation (left).
Fig. 2. Climate manipulation techniques (right).
References
[1] Feng, X. J., Simpson, A. J., Wilson, K. P., Williams, D. D.
and Simpson, M. J. (2008) Nature Geosci. 1, 836-839.
[2] Frey, S.D., Drijber, R., Melillo, J. (2008) Soil Biol.
Biochem. 40, 2904-2907.
[3] Toberman, H., Freeman, C., Evans, C., Fenner, N. and
Artz, R. R. E. (2008) FEMS Microbiol. Ecol. 66, 426-436.
[4] Sowerby, A., Emmett, B., Beier, C., Tietema, A.,
Penuelas, J., Estiarte, M., van Meeteren, M.J.M., Hughes,
S., Freeman, C. (2006) Soil Biol. Biochem. 37, 1805-1813.
[5] Elvert, M., Boetius, A., Knittel, K., Jorgensen, B. B. (2003)
Geomicrobiol J. 20, 403-419.
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