TABLE CONTENTS

Soil Nematode Communities under Climate Change
Kardol, P.
Environmental Sciences Division, Oak Ridge National Laboratory, PO Box 2008, Oak Ridge Tennessee, TN
37821-6422, USA; Department of Ecology and Evolutionary Biology, University of Tennessee, 569 Dabney
Hall, Knoxville, TN 37996, USA
Through their role in decomposer food webs and plant root / rhizosphere interactions,
nematodes play an important role in climate change effects on ecosystem functioning. I used
the long-term multi-factor Old-Field Community Climate and Atmosphere Manipulation
(OCCAM) experiment to examine single and interactive effects of elevated CO 2 ,
temperature, and water availability on soil nematode community composition and diversity.
The OCCAM experiment consists of constructed plant communities (including C3 and C4
grasses, forbs, and legumes) in open-top chambers. After four years, it was found that the
relative importance of single factor vs. interactive effects on abiotic and microbial soil
properties varied among years and depended on the response measured. Importantly, plant
species differed in their responses to the climate change factors, resulting in changes in plant
community composition. Such shifts in plant dominance patterns, which can affect quantity
and quality of rhizodeposition and litter input to the soil, probably have much larger effects
on soil nematodes communities than direct effects of climate change factors. In each
chamber, I collected bulk soil samples as well as soil samples under the two dominant plant
species, Lespedeza cuneata (an exotic legume) and Festuca pratense (a native grass), whose
cover were significantly affected by the climate change treatments and thereby reflect the
changes in plant community composition. Preliminary results show that, in general, number
of nematodes were lower in dry than in wet treatments and were lower under Lespedeza than
under Festuca. [CO 2 ] and temperature had less effect. Multivariate analyses indicate plant
species × treatment interactions, which suggest that direct effects of climate change on soil
nematode communities can depend on, or be overruled, by changes in the plant community
composition. I will discuss the latest results using a conceptual framework comprising plant
community dynamics, rhizosphere interactions, and decomposer food webs.
5 th International Congress of Nematology, 2008 105