NEMATODE DIVERSITY OF NATIVE SPECIES OF VITIS IN CALIFORNIA

From 1990 through 1992, nematodes were extracted from soil samples tak en from the rhizosphere of native species of grapes from four areas of northern California and two areas of southern California. For compari son, samples from domestic grapes as well as a putative hybrid of Viti s californica and V. vinifera were also taken. Rhizosoil from Californ ia native grapevine contained many more species of nematodes than did soil obtained from cultivated forms of V. vinifera. Taxonomic and trop hic diversity was much higher in nematodes from sampling sites from na tive grapes than in those from grapes maintained in vineyard situation s. Ordination methods using correspondence analysis showed both simila rities and differences in the faunal assemblages of nematodes from the different sampling sites, based on indexes of species and trophic gro ups. Collected data indicate that nematode communities with high troph ic and taxonomic diversity have a lower numerical density of plant par asites.