VARIATION IN SPECIES RICHNESS OF PLANTS AND DIVERSE GROUPS OF INVERTEBRATES IN 3 CALCAREOUS GRASSLANDS OF THE SWISS JURA MOUNTAINS

mSpecies richness and abundance of vascular plants and several groups of invertebrates (spiders, oribatid mites, diplopods, grasshoppers and bush crickets, ground beetles, butterflies and terrestrial gastropods ) were recorded in three calcareous grasslands (Nenzlingen, Movelier a nd Vicques) in the northwestern Swiss Jura mountains. Species richness varied both between taxonomical groups and between sites (species ric hness ranges: 96-116 vascular plants, 60-66 spiders, 18 oribatid mites at each site, 1-7 diplopods, 10-16 grasshoppers and bush crickets, 19 -21 ground beetles, 32-46 butterflies and 15-21 terrestrial gastropods ). Species overlap (number of species that occurred at all sites) was relatively large in terrestrial gastropods (59.1%), butterflies (56.5% ), vascular plants (53.8%) and grasshoppers (47.1%), but relatively lo w in oribatid mites (32.3%), spiders (25.0%), ground beetles (18.4%) a nd diplopods (12.5%). Diversity expressed by the Shannon-Wiener index (H') was compared for five groups of invertebrates. Diversity was larg est in spiders and ground beetles and lowest in terrestrial gastropods . Different taxonomical groups had their maximum diversity at differen t sites: each grassland had the highest diversity in at least one grou p. The three sites also varied in the abundance of different invertebr ate groups. Most groups had the highest densities in Nenzlingen and th e lowest densities in Vicques. All three sites contained a high propor tion of species listed in the Red Data Book of Switzerland with values averaging 49.5% in grasshoppers and bush crickets, 28.9% in butterfli es, 18.9% in vascular plants, 11.2% in terrestrial gastropods, and 6.7 % in ground beetles. One spider species (Oxyptila pullata) and two mit e species (Epilohmannia cylindrica minima and Pergalumna myrmophila) w ere recorded for the first time in Switzerland.