STRUCTURE OF THE NEMATOFAUNA IN SPANISH MEDITERRANEAN CONTINENTAL SOILS

We studied the nematofauna in cultivated Luvisols in the Spanish Centr al Region in terms of multivariate statistical relationships between n ematode groups and environmental variables (habitat, hosts, soil textu re, and quantitative edaphic variables). Three large nematode associat ions were recognized, one group being characteristic of the region's r otational crops (Pratylenchus, Ditylenchus, Helicotylenchus, Tylenchor hynchus, Rotylenchus, other Dorylaimidae, Plectus, and Tylenchus), a s econd group related to cereal monoculture and wild gramineae associate d with bush formations (Heterodera, Criconemoides, Discolaimus, and ot her Rhabditidae), and a third group characteristic of uncultivated soi ls (Paratylenchus, Xiphinema, Hemicycliophora, Mononchus, Tripyla, and Alaimus). Paratylenchus and Tylenchus species were shown to have an i ndicator value for certain edaphic properties, especially soil texture , and may be regulated by the clay content of the soil.