Lichen Populations on Arid Soil Crusts around Sheep Watering Places in South Australia

Microbiotic soil crusts - a review of their roles in soil and ecological processes in the rangelands of Australia

“…In a similar study of piospheres, Rogers and Lange (1971) found that stocking pressure caused a differential destruction of lichen species close to the watering point. Unlike vascular plants, all lichens were affected to a certain extent, and decreased in frequency as stocking intensity increased.…”

“…As they require a stable substrate on which to develop, stabilization of the surface by algal filaments is a precursor to their development. The growth of lichens results in marked increases in the capability for nitrogen fixation (Shields et al 1957;Rogers et al 1966;Rogers and Lange 1971;Rogers 1974). Where a strong grass canopy develops, overtopping and competition for sunlight, moisture and nutrients, and possible allelopathic effects of litter may lead to reductions in non-vascular cover.…”

A Field Guide to Biological Soil Crusts of Western U.S. DrylandsA Field Guide to Biological Soil Crusts of Western U.S. Drylands

“…Reduced quadrat size is also useful if a goal of the study is to observe greater detail in biological crust composition in relation to environmental variation within the site. For example, Rogers and Lange (1971) used 15 x 20-cm quadrats to examine changes in crust floristics related to stock watering points in semi-arid and subtropical Australia. Other Australian studies have employed 0.5 m 2 subplots within larger plots to assess cover and frequency of crustal organisms (Eldridge and Bradstock 1994;Eldridge 1996 Daubenmire 1959) for estimating biological crust cover (Rosentreter 1986;Ponzetti et al 1998).…”

“…Lichens use a combination of adaptive thallus structures and pigments (Blum 1973;Galun et al1982), water storage capacities, tolerance of frequent and/or prolonged inundation, and/or an ability to fix atmospheric nitrogen to increase resistance to disturbance. For example, Rogers and Lange (1971) showed that lichens Collema coccophorum and Heppia lutosa (H. despreauxii) were the least affected by sheep trampling around a watering point compared to other taxa. These lichens are able to fix atmospheric nitrogen and to store greater amounts of water than stratified green lichens (Galun et al 1982).…”

“…In a comparison of species inside and outside a grazing exclosure, vagrant foliose lichens Chondropsis semiviridis and Xanthoparmelia convoluta, crustose lichens Diploschistes scruposus and Caloplaca spp., and the squamulose lichens Peltula imbricata were associated with ungrazed sites (Table 4. 1;Crisp 1975;Eldridge and Koen 1998). The gelatinous lichen Collema coccophorum was the most tolerant of livestock trampling (Rogers and Lange 1971;Eldridge 1996).…”