Surrogates for cryptogam conservation - associations between mosses, macrofungi, vascular plants and environmental variables

Cryptogams are rarely included in conservation planning and management. This study aims to improve the data available for cryptogam conservation by focusing on two groups of cryptogams, mosses and macrofungi, to test the usefulness of vegetation type, vascular plants and environmental variables, including substrate, as surrogates for cryptogams in achieving satisfactory conservation outcomes. Sites from four vegetation types (wet forest, heathy woodland, grassy woodland and alpine heath) in the Hobart region of Tasmania were surveyed over a period of several years for vascular plants, mosses and epigeous macrofungi using permanent plots. Repeated sampling of the macrofungi ensured that a reasonable proportion of the taxa likely to be present were recorded. A total of 284 vascular plants, 71 mosses and 233 macrofungi were recorded. Ordination and analysis of similarity both showed that the four vegetation types were significantly different from each other; this pattern occurred for vascular plants, mosses and macrofungi. Congruence between the three taxonomic groups was tested using Partial Mantel tests; all pairwise associations were highly significant, showing highly predictive r-values. Significant and predictive associations occurred between environmental and substrate variables and biotic groups (vascular plants, mosses and macrofungi, and their various subsets). Canopy cover was the best single predictor of most biotic groups. Particular combinations of significant environmental variables had higher correlations with biotic groups than single variables, for example the combination of altitude, canopy cover and geology had higher r-values than any of these factors individually. Mosses and macrofungi exhibited high substrate fidelity across time and space. Substrate preferences of macrofungi did not vary among vegetation types, but mosses in wet forest occurred on a wider range of substrates than the same species in other vegetation types. Iterative, optimisation, fully random and stratified random methods were compared for their effectiveness in the selection of sites for the conservation of vascular plants, mosses and macrofungi. When 10% of sites were selected for reservation there was little commonality in site selection between the three taxonomic groups. When 30% of sites were selected, at least 48% of all taxa were reserved by all approaches tested. The most useful data sets for selecting sites representative of the three taxonomic groups were vascular plants, named species from all three taxonomic groups and sites selected randomly with equal proportions of each vegetation type. The results suggest that coarse scale conservation of vegetation types with reservation of at least 30% of their area should conserve common mosses and macrofungi. However, at the site scale, uncommon taxa (i.e. taxa only found on a single site) of mosses and macrofungi are not concordant with vascular plants. Associations of moss and macrofungal species with particular substrates and microhabitats may assist with site selections for reservation. For adequate management, further research is required on the occurrence and substrate and habitat specificity of rare taxa.