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Elevated CO2 and Warming Reduce the Abundance of Plant-Feeding Nematodes in a Wyoming Grassland

Paper Reviewed
Mueller, K.E., Blumenthal, D.M., Carrillo, Y., Cesarz, S., Ciobanu, M., Hines, J., Pabst, S., Pendall, E., de Tomasel, C.M., Wall, D.H. and Eisenhauer, N. 2016. Elevated CO2 and warming shift the functional composition of soil nematode communities in a semiarid grassland. Soil Biology & Biochemistry 103: 46-51.

Nematodes comprise the most abundant multicellular animals on Earth. A handful of soil can easily contain thousands of these microscopic worms.

Writing as background for their work, Mueller et al. (2016) note that nematodes can "play an important role in shaping the functions of mixed-grass prairies because grasslands typically have high nematode densities and, for example, plant productivity is sensitive to shifts in nematode density." However, little is known about the influence of climate change on nematodes and how that might impact the future of such grasslands. For these reasons, the team of eleven scientists set out to "assess the impacts of climate change on soil nematodes in a semiarid grassland using a 7-year, factorial manipulation of temperature and [CO2]."

The experiment was conducted out-of-doors using FACE technology and infrared lamps in Wyoming, USA. There, over a period of seven years, the researchers exposed portions of a semi-arid, mixed-grass prairie to either normal or CO2-enriched (600 ppm) air during sunlit hours of the plant growing season, while simultaneously exposing the different CO2 treatments to either ambient or elevated (+1.5°C during the day and +3°C at night) air temperature. Then, in the final year of the experiment, Mueller et al. collected soil cores from each of the treatments from which they extracted, counted and classified nematodes.

Results indicated that "elevated CO2 and warming decreased the abundance of plant-feeding nematodes," resulting in nematode communities that "were even more dominated by [species] that feed on bacteria and fungi." This finding, according to Mueller et al., suggests that "climate change could alter soil functioning in semiarid grasslands," which alteration could well be positive. For as the team of researchers further state, "the lower abundance of plant-feeding nematodes could facilitate positive effects of elevated CO2 and warming on plant productivity" (emphasis added). And that they apparently did, as the authors note elsewhere in their paper that "warming and elevated CO2 tended to have positive, but sub-additive effects on the number and length of fine roots," citing the work of Carrillo et al. (2014) and unpublished data from their study.

Reference
Carrillo, Y., Dijkstra, F.A., LeCain, D., Morgan, J.A., Blumenthal, D., Waldron, S. and Pendall, E. 2014. Disentangling root responses to climate change in a semiarid grassland. Oecologia 175: 699-711.

Posted 25 January 2017