DISTRIBUTION AND FLORISTICS OF TERRICOLOUS LICHENS IN SOIL CRUSTS IN ARID AND SEMIARID NEW-SOUTH-WALES, AUSTRALIA

This paper examines the distribution of terricolous lichens at a regio nal scale across seven landscape types over 60000 km(2) in western New South Wales. Data are also presented on the distribution of lichens w ithin a geomorphic sequence of runoff and runon zones on a red earth s oil near Cobar. On a regional scale, 48 taxa from 23 genera were colle cted from 282 sites in semi-arid and arid eastern Australia, Of these, 74% were crustose or squamulose, and the remainder (26%) were foliose . Six genera (Acarospora, Endocarpon, Catapyrenium, Diploschistes, Pel tula and Xanthoparmelia) accounted for 57% of species. Landscape type was a poor predictor of lichen floristics or crust cover. Instead, a c ore group of species comprising Collema coccophorum, Heppia despreauxi i, Endocarpon rogersii, E. simplicatum var. bisporum, E. pallidum, Pso ra decipiens, Peltula patellata sap. australiensis, Catapyrenium squam ulosum and Synalissa symphorea, occurred in all landscape types. Plain s with red earths had the greatest mean number of species per site (11 .2) and the greatest mean crust cover (27.7%). Plains of calcareous ea rths yielded the greatest number of species (38). Across all sites, cr ust cover was a poor predictor of lichen species richness. However, on landscape types with non-calcareous soils, mean crust cover explained 88% of the variation in mean number of species. Whilst there was no d ifference in total number of species across a sequence of geomorphic z ones, crust cover was significantly greater in the interception zones (79.0%) compared with either the run-on (6.6%) or run-off (24.0%) zone s. These distributional data are compared with other published and unp ublished studies from similar areas in Australia. The role of terricol ous crusts as indicators of ecosystem health, and the influence of lan d management on crust cover and subsequent landscape stability are dis cussed.