This paper examines the distribution of terricolous lichens at a regional scale across seven landscape types over 60 000 km2 in western New South Wales. Data are also presented on the distribution of lichens within a geomorphic sequence of runoff and runon zones on a red earth soil near Cobar. On a regional scale, 48 taxa from 23 genera were collected 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, Peltula and Xanthoparmelia) accounted for 57% of species. Landscape type was a poor predictor of lichen floristics or crust cover. Instead, a core group of species comprising Collema coccophorum, Heppia despreauxii, Endocarpon rogersii, E. simplicatum var. bisporum, E. pallidum, Psora decipiens, Peltula patellata ssp. australiensis, Catapyrenium squamulosum and Synalissa symphorea, occurred in all landscape types. Plains 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 earths yielded the greatest number of species (38). Across all sites, crust 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 difference in total number of species across a sequence of geomorphic zones, crust cover was significantly greater in the interception zones (79.0%) compared with either the run-on (6.6%) or run-off (24.0%) zones. These distributional data are compared with other published and unpublished studies from similar areas in Australia. The role of terricolous crusts as indicators of ecosystem health, and the influence of land management on crust cover and subsequent landscape stability are discussed.
The influence of the funnel ant (Aphaenogaster barbigula) on water infiltration was studied on an aeolian soil in a semi-arid Callitris glaucophylla woodland in eastern Australia. At the study site at Yathong Nature Reserve, densities of up to 37 nest entrances m-2 were recorded in some areas, equivalent to a density of 88 000 entrances ha-1 over small areas or 0.9% of the surface area of the landscape. Seventy-two per cent of the entrances were actively being used by the ants. Steady-state water infiltration on soils with entrances averaged 23.3 mm min-1 which was about four times that on entrance-free soils. As the diameter of the nest entrance increased, water penetrated deeper into the soil. The results provide further evidence that ants have a marked influence on redistribution of water in semi-arid environments.
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