With the impending threat of climate change, greater understanding of patterns of species distributions and richness and the environmental factors driving them are required for effective conservation efforts. Species distribution models enable us to not only estimate geographic extents of species and subsequent patterns of species richness, but also generate hypotheses regarding environmental factors determining these spatial patterns. Projected changes in climate can then be used to predict future patterns of species distributions and richness. We created distribution models for most of the flightless ground beetles (Carabidae) within the Wet Tropics World Heritage Area of Australia, a major component of regionally endemic invertebrates. Forty-three species were modelled and the environmental correlates of these distributions and resultant patterns of species richness were examined. Flightless ground beetles generally inhabit upland areas characterised by stable, cool and wet environmental conditions. These distribution and richness patterns are best explained using the time-stability hypothesis as this group’s primary habitat, upland rainforest, is considered to be the most stable regional habitat. Projected changes in distributions indicate that as upward shifts in distributions occur, species currently confined to lower and drier mountain ranges will be more vulnerable to climate change impacts than those restricted to the highest and wettest mountains. Distribution models under projected future climate change suggest that there will be reductions in range size, population size and species richness under all emission scenarios. Eighty-eight per cent of species modelled are predicted to decline in population size by over 80%, for the most severe emission scenario by the year 2080. These results suggest that flightless ground beetles are among the most vulnerable taxa to climate change impacts so far investigated in the Wet Tropics World Heritage Area. These findings have dramatic implications for all other flightless insect taxa and the future biodiversity of this region.
Abstract. 1. Development of foliage cover and a layer of leaf litter are two factors considered important for the successful recolonisation of soil and litter arthropods during the early stages of rainforest restoration; however, this needs to be tested explicitly.2. We employed a manipulative field experiment to assess the effects of shading and litter depth on colonisation patterns of soil and litter arthropods in created habitat patches at five replicated sites within pasture adjacent to rainforest remnants on the Maleny plateau of subtropical eastern Australia.3. Habitat patches were created by adding sterilised mulch at two depths (shallow 3-5 cm, deep 10-15 cm) under three levels of shading (none, 50%, 90%). Responses of arthropods to treatments were analysed at two levels of taxonomic resolution: 'ordinal-sorted arthropods' (all arthropods sorted to order ⁄ class) and ant species (Hymenoptera: Formicidae).4. Shading, at both 50% and 90%, encouraged colonisation by arthropods characteristic of rainforest. Colonisation by pasture-associated arthropods declined progressively with increased shading. Effects of mulch depth were significant only for rainforest-associated ant species, which responded positively to shallow mulch within shaded plots.5. The results confirm that canopy cover is indeed one of the primary attributes influencing colonisation patterns of arthropods in restored vegetation. More widely spaced plantings may facilitate some colonisation by rainforest arthropods. However, in order to suppress invasion by pasture-associated arthropods, it may be necessary to establish a fully closed canopy.
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