Does coarse woody debris density and volume influence the terrestrial vertebrate community in restored bauxite mines?

Coarse woody debris (CWD) is a critical functional and structural component of forest and woodland ecosystems, providing habitat for many species, and is an important consideration in forest and woodland restoration. CWD is very slow to develop naturally so, to accelerate the return of CWD-dependent species to restored areas, CWD is commonly returned manually. However, few studies have tested the effectiveness of such a strategy. We investigated whether the provision of CWD, heaped into 'habitat piles' of varying density (0.4-5.7 piles ha−1), was effective in accelerating recolonisation by reptiles, frogs and mammals into 3-year old restored bauxite mine-pits in south-western Western Australia. Both reptile and mammal communities, and the abundances of some individual species, differed significantly between unmined and restored forest but the provision of CWD had only a weak effect in accelerating recolonisation. Acritoscincus trilineatus abundance showed a weak positive relationship with habitat pile density and both Cryptoblepharus buchananii and Christinus marmoratus, species that are very rare in restoration, were recorded adjacent to habitat piles in two and one mine-pits respectively. The weak effects of CWD in accelerating recolonisation were likely due to the differences in vegetation between unmined and restored forest, resulting in restored forests being primarily inhabited by generalist species that did not require CWD, and the highest habitat pile densities being ⩽6% of log densities in unmined forest, suggesting that CWD-dependent species perceived all mine-pits as having similarly low levels of CWD, compared to unmined forest. Our results suggest that the provision of CWD in restored areas is critical to accelerate recolonisation of CWD-dependent fauna, but this will require consideration of both CWD spatial connectivity and temporal continuity. Spatial connectivity would be best achieved through CWD densities that approximate those in reference ecosystems, whereas temporal continuity will be harder to achieve, particularly in systems where CWD is slow to develop, and will require the development of innovative techniques and long-term management. However, ensuring the spatial connectivity and temporal continuity of CWD in restored areas should greatly increase their biodiversity value.