Effects of variable-intensity logging on mammals, reptiles and amphibians at Waratah Creek, southeastern New South Wales

Abstract

Populations of arboreal marsupials, small ground-dwelling mammals, reptiles and amphibians were assessed in forest before and after logging. Different levels of canopy retention were specified to estimate the effect of varying intensities of logging on these fauna. The logging treatments imposed were; unlogged, and the retention of approximately 72%, 58% and 30% of the original canopy cover. This corresponded to 62%, 52% and 21 % retention of the original tree basal area on each logged area. The objectives of the study were to determine the sensitivity of species to logging, both in terms of the intensity of the initial impact and in terms of the time to recovery following disturbance, and to develop methods for managing areas within wood production forests where special wildlife values have been identified. A total of 53 species was recorded in the 500 ha study area, only 18 (34.0%) of which were abundant enough for assessments to be made about the effects of logging. The arboreal marsupials, in particular the Greater Glider Petauroides volans, were among the species more sensitive to logging disturbance. The small, ground-dwelling mammals and the reptiles that were sampled adequately in this study appeared to be relatively unaffected by logging or they recovered quickly (most within eight years, and probably all within 10?15 years) following logging. Despite a large survey effort, insufficient data were available to assess the effects of logging on most species of frogs, although two species may have been advantaged. The species requiring management consideration include those that declined as a result of logging, but which had not recovered within eight years (the Greater Glider, the Yellow-bellied Glider Petaurus australis, the Sugar Glider P. breviceps, and the skink Niveoscincus coventryi), the species that declined in both logged and unlogged areas (the frogs Pseudophryne bibronii, Limnodynastes peronii, Geocrinia victoriana and Heleioporus australiacus), and the species for which the data were too sparse to make any assessments. It is unclear when the species most disadvantaged by integrated logging, that is, the large gliding possums, will recolonize the logged areas. The persistence of these gliders was attributed to the retention of unlogged forest within and adjacent to logged areas. This highlights the role of riparian reserves ("wildlife corridors") and filter strips in retaining residual populations of the Greater Glider and the Yellow-bellied Glider until the logged areas are suitable for recolonization, and the importance of determining the effective size for these unlogged reserves. The data were not sufficient to determine conclusively whether reduced logging intensity at the levels applied was a better option than standard logging practices for managing populations of gliding possums in these forests. The results of this study, which was conducted in a forested landscape that was multi-aged but predominantly unlogged, may not be comparable to intensively-managed forests in which there is a lower proportion of unlogged forest and where multiple logging events have occurred.