Ecology of the corticolous lichens on Pinus radiata at five sites of increasing age near Linton, Victoria, Australia



Abstract Thirteen lichen species were studied on trunk segments of Pinus radiata D.Don between 1.0 and 1.5m above-ground from five plantings of known, different ages near Linton, Victoria. Significant frequency and size-class differences were found for most species between sites. These parameters generally increased up to 32 years, and then either declined or showed evidence of recolonization by small thallus size-classes in some species. Nevertheless, only relict populations for any species were present at 52 years. Most species had no aspect preferences; only three species had a significant majority of their thalli on the western trunk face. Site-species association frequency analyses clustered, as pairs, the 11 and 52, and 16 and 39 year old sites. These site patterns were correlated with a number of environmental factors as well as species abundance at the sites, but there is also a possible response by the community to bark shedding, seen after 32 years, with a return to earlier colonization states in the system. This cyclic pattern is similar to a competitive hierarchy succession, although due to accelerating chronic disturbance (bark shedding) the system may be subject to secondary succession and, ultimately, to severe degradation.