Are Collembola useful as indicators of the conservation value of native grasslands?

Twenty two predominantly native grassland sites of varying levels of disturbance and community type were sampled for Collembola using a suction sampler in spring. Specimens were identified to species and composition and abundance of the collembolan fauna at each site compared using a number of methods. Different analyses did not produce a similar ranked order for the sites except that the most pristine site, of highest conservation value, always ranked highly and the three most weed infested disturbed sites were always at the bottom of the rankings. The ranking method which conformed most closely to ranked weediness values was that based simply on species richness and species abundance of both exotic and native species considered separately. No congruence was found between rankings of sites based on species richness of ants, carabid beetles and Collembola indicating that caution should be applied when using surrogate taxa. The cluster analysis indicated that grassland type was the most important factor determining the composition and abundance of collembolan faunas. It is concluded that the intrinsic variation in these ecological systems is too great for a linear response to disturbance to be shown by the invertebrates studied here which makes it unlikely that a single, reliable indicator can be found.