Humans activity such as land transformation through urbanization, deforestation and agricultural intensification is the principal driving force behind loss of biodiversity. In addition, human influence is rapidly changing the climate by emission of greenhouse gases. Global air temperature is predicted to increase by 2–5 °C in the next 50–100 years. An increase in air temperature results in increased soil temperature. Soil is a dynamic system in which organisms interact with each other and form complex food webs. Nematodes are at the center of the soil food web because they represent multiple trophic levels. Nematodes are categorized to different trophic levels based on their feeding habits and different colonizer-persister (CP) classes based on life history characteristics. Nematode community structure provides good information on the condition of the soil food web and serves as an indicator of environmental disturbances. Therefore, a soil warming experiment was conducted to determine the response of nematode food webs to increasing temperatures in an agricultural ecosystem at Knoxville, TN, USA. The soil warming system maintained a temperature difference of 5° C between warming and control plots by use of heating cables and dataloggers. Thermocouples and watermarks were installed to measure temperature and moisture.
Results/Conclusions
Nematode richness in warmed soils was consistently low compared to control treatments, whereas abundance in the warmed soils was higher compared to control treatments. These results indicate that some nematodes increase in numbers with increasing temperature; but the abundance of others decreases. Nematode richness and abundance were analyzed by trophic group and CP class. Soil warming gradually decreased the richness and the abundance of higher trophic groups such as predators and omnivores, and higher CP classes (CP-4, CP-5) nematodes. On the other hand, warming increased the abundance of lower trophic groups such as bacterivores and plant feeders. Increases in soil temperature may enhance microbial activity, resulting in increased abundance of bacterivores. However, soil warming decreased both abundance and richness of higher trophic and CP classes, which are critical for the maintenance of a full suite of soil ecosystem services.