Avifaunal ecology and responses to post-fire succession of buttongrass moorlands in the Tasmanian Wilderness World Heritage Area
thesisposted on 2023-05-26, 04:24 authored by Chaudhry, TA
Fire management has become an increasingly critical issue in areas of high conservation value such as the pyrogenic buttongrass moorlands in the Tasmanian Wilderness World Heritage Area. The moorland avifauna is depauperate, comprised of only three cryptic, ground-dwelling resident species that depend exclusively upon moorlands in the study area. These include the Southern Emu-wren (Stipiturus malachurus), Striated Fieldwren (Calamanthus fuliginosus), and Ground Parrot (Pezoporus wallicus), in addition to a small number of species that are typically associated with adjacent forested habitats. This thesis is the first comprehensive study of the buttongrass moorland avifauna and investigated responses to post-fire succession primarily to help guide fire and conservation management. The replicated space-for-time study included sites in low productivity, blanket moorlands at Lake Pedder (n = 12; 2-54 years post-fire) and in moderate productivity, eastern moorlands at Lake St Clair (n = 14; 1-44 years post-fire). Avifaunal diversity, density, and habitat use over three seasons were quantified and analysed in relation to fire age, soil productivity and composition, structure, and spatial characteristics of habitats at both locations. Observed patterns of avifaunal diversity, density, and habitat use across the two chronosequences were complex and revealed high levels of inter-specific and inter-site variation in relation to habitat variables. Overall, mean densities of the resident species at Lake Pedder increased across the chronosequence, whereas at Lake St Clair they peaked 2-8 years post-fire. Mean densities of the non-resident species did not exhibit any consistent trends in relation to fire age. Observations of habitat use demonstrated that the resident and non-resident species used riparian and edge habitats disproportionately to their availability at both locations when compared to the moorland matrix. Surveys of potential arthropod prey resources conducted in matrix and riparian habitats at Lake St Clair indicated that mean abundance and mean energy content across orders were greater in riparian habitats and mid-seral sites, respectively. Thus, patterns of habitat selection by insectivorous species at Lake St Clair also appeared to reflect the differing availabilities of potential arthropod prey. Lastly, a paired before-after-control-impact study conducted at Lake St Clair (n = 4) indicated that hazard-reduction burning in moorlands may result in overall reductions in resident avian densities and increases in non-resident densities in the short-term (< 1.5 years post-fire). The implications of these findings are discussed in relation to current fire management practices and recommendations are provided to facilitate the conservation of critical resources for the moorland avifauna across the landscape and over time.
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