Nematodes as bioindicators of dry pasture recovery after temporary rye cultivation

Soil and plant parasitic nematodes were sampled from the top 10 cm of a luvisol in dry grassland north of Madrid (Central Spain). A natural pasture and two grazed pastures which had been cropped with rye 1 and 6 yr before, respectively, were compared by multivariate statistical analysis of the nematode fauna. Results from stepwise discriminant analysis demonstrated the influence of agricultural management on the abundance of the nematode community of these pasture soils. Specifically, it was found that Paratylenchus and Rhabditidae can have a discriminative value of the recovery of these soil ecosystems. Among the indices used to analyze the abundance, diversity and maturity of the nematode community, only plant parasite index (PPI) detected significant differences among pastures, decreasing its values as recovery time after human intervention increased, with the significantly highest value in the recently cropped (C) pasture. It is concluded that length of time after cropping influences the abundance more than the diversity of the nematodes present in pastures of these areas, and that multivariate statistical analyses are the most useful tests to detect differences. The role of nematodes as biological indicators of the degree of recovery of these soils after human disturbance is noted.