Previous research has shown that changes in aboveground diversity can drastically alter the diversity of belowground communities. Less is known about the reciprocity of this relationship, however it is likely that changes in belowground diversity can have serious consequences for aboveground communities. This interaction is particularly important when combined with the process of agricultural domestication. Because most plant domestication occurred hundreds to thousands of years ago, little is known about the early effects of the plant domestication process on belowground communities. However, the domestication of Switchgrass (Panicum virgatum) in North America began less than 100 years ago, and provides an excellent opportunity to investigate these changes. Focusing on belowground nematode communities, we asked: How has the recent domestication of Switchgrass affected the community structure of soil nematodes? To answer this question, we analyzed soil nematode communities under Switchgrass in natural prairie systems and in domesticated Switchgrass monocultures. Knowing how the structure of soil nematode communities is affected by Switchgrass domestication may help us better understand the mechanisms by which high numbers of a few herbivorous species of nematodes are achieved, dramatically decreasing plant production in almost every domesticated crop plant on earth.
Results/Conclusions
Seven remnant prairies and 8 field monocultures of Switchgrass were identified and sampled in Eastern Nebraska. In a comparison of a pair of sites, one in a well-preserved remnant prairie and the other in a 20-year-old monoculture of Switchgrass, morphology-based taxonomic analysis of a subsample of the nematode communities shows that nematode genus diversity is higher in the prairie site with high plant richness than in the monoculture site. In the prairie site, a Switchgrass stand having an estimated area of 6.75 m2, 9 plant species including Switchgrass were present. Among the 161 randomly selected nematodes from a soil sample in this site, 29 genera were identified. In the monoculture site of equal area, 1 plant species was present. Among the 158 randomly selected nematodes from this site, 17 genera were identified. A dramatic increase in the abundance of a particular herbivorous nematode genus, Basiria, was also noted. These initial results indicate significant structural changes in the nematode community under a domesticated Switchgrass monoculture, highlighted by an increase in abundance of herbivorous nematodes. More rigorous investigations into the mechanisms that cause this change in nematode community structure are important.
