Nematode diversity of native species of Vitis in California

From 1990 through 1992, nematodes were extracted from soil samples taken from the rhizosphere of native species of grapes from four areas of northern California and two areas of southern California. For comparison, samples from domestic grapes as well as a putative hybrid of Vitis californica and V. vinifera were also taken. Rhizosoil from California native grapevine contained many more species of nematodes than did soil obtained from cultivated forms of V. vinifera. Taxonomic and trophic diversity was much higher in nematodes from sampling sites from native grapes than in those from grapes maintained in vineyard situations. Ordination methods using correspondence analysis showed both similarities and differences in the faunal assemblages of nematodes from the different sampling sites, based on indexes of species and trophic groups. Collected data indicate that nematode communities with high trophic and taxonomic diversity have a lower numerical density of plant parasites.