Spatial fidelity of plant, vertebrate, and invertebrate assemblages in multiple-use forest in eastern Australia

The design of a protected areas network that contains or represents as many species as possible (maximum complementarity of areas) is a first step toward in situ conservation of species biodiversity. In the absence of complete species inventories, however, area selection mast employ surrogate data such as the distribution of plant or vertebrate species. The degree to which the use of these taxa results in a network of sites with maximum complementarity for others depends on levels of assemblage fidelity among taxa. Assemblage fidelity is defined here as the degree to which assemblages from different phylogenic groups co-occur in space and time. We examined the spatial fidelity of ground-active invertebrate (ants and several beetle families.' Carabidae, Scarabaeidae, Pselaphidae), vascular plant, and vertebrate assemblages (birds, small mammals, frogs, and reptiles) at 56 sites in a range of eastern Australian forest types. We used unlogged (n = 32) and logged (n = 24) forest sites. Assemblage fidelity was assessed by ordination and Mantel correlation, and patterns of species richness and species turnover that helped explain the findings were analyzed by simple correlation, cluster analysis, and two indices of β diversity. Our analyses revealed general assemblage fidelity among plant, vertebrate, and invertebrate assemblages, and results were consistent in both unlogged and logged forest. In several forest types, however, fidelity among invertebrates and plants was low due to high invertebrate turnover. Overall levels of species turnover were much higher for vascular plants and invertebrates than for vertebrates. Species richness patterns at individual sites were generally uncorrelated among taxa. Our findings suggest that (1) the exclusion of invertebrates from biodiversity surveys cannot be justified on the assumption that plant and vertebrate assemblages act as surrogates for invertebrate species-level biodiversity or on the basis of cost-efficiency; (2) both spatial fidelity and species turnover are useful for evaluating the role of selected taxa as surrogates for the species-level biodiversity of others; (3) the selection of sites for in situ biodiversity conservation should consider taxa that exhibit high levels of species turnover; and (4) the inclusion of invertebrates in biodiversity surveys may offer considerable cost savings and be more representative of species biodiversity than conventional plant and vertebrate surveys.