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Hollow-using fauna are thought to be particularly vulnerable to timber harvesting, and habitat for these species is often managed by retaining single hollow-bearing trees or patches of hollow-bearing trees within the harvested area. This study examined tree retention, survival and use by arboreal mammals in 27 small clumps of trees (0.04–0.21 ha) retained at ten partial harvest sites and 24 clumps of trees in nearby unharvested sites in Tasmania, Australia. Harvested sites were assessed on three occasions (1999, 2005–06 and 2014) and unharvested sites on two occasions (2005–06 and 2014). Of the retained clumps in harvested areas, 96% contained at least two habitat trees at the time of first survey (one year after harvest) which is the minimum required under the Tasmanian Forest Practices Code. Loss of retained trees in clumps between 2005–06 and 2014 was higher in harvested sites (average of 11.7% of all trees and 1.5% of habitat trees per clump) than unharvested sites (average of 2.8% of all trees and 0.3% of habitat trees per clump), but was comparable to or lower than rates of loss in many other studies. Trees were more likely to fall if they were dead and had little burn damage at the time of last survey. Factors found to influence tree death included the interaction between burn damage and the size of the tree, with the likelihood of a heavily burnt, average sized tree dying being twice that of an unburnt tree. Scratch marks from arboreal mammals were more prevalent in large trees with visible hollows, particularly in the clumps in harvested areas. In conclusion, the Tasmanian Forest Practices Code provisions were generally implemented as required and the evidence suggests the retained clumps of trees survive and are effective to some degree at providing habitat and promoting recolonisation by fauna in partial harvest coupes. However, further work is required to assess the adequacy of the clump provisions, when combined with management for other values in production forests, for maintaining hollow-using fauna throughout their range. [ABSTRACT FROM AUTHOR]

We assessed rates of organic matter (OM) processing in coarse gravel and fine benthic sediment, along with water temperature, in four clearfell harvested and two undisturbed headwater streams flowing through wet eucalypt forest in southern Tasmania, Australia. Clearfell forestry in Tasmanian wet eucalypt forest involves felling of all timber followed by a high intensity regeneration burn to provide a receptive mineral seedbed for seedling growth. Bacterial carbon production and cellulose decomposition potential (together referred to as OM processing) were measured seasonally 3-5 years before and 2-4 years after harvesting in each stream. We employed a staircase design (staggered harvesting treatments) within a multiple before-after control-impact design to distinguish harvesting effects from natural variation. Clearfell harvesting raised the yearly mean water temperature by between 0.25 °C and 0.94 °C, and raised the maximum water temperature by between 0.84 and 1.6 °C. Rates of cellulose decomposition were not significantly correlated with sediment temperature but bacterial carbon production showed weak, significant correlations with temperature in fine (r = 0.20, P = 0.01, n = 137) and coarse gravel sediment (r = 0.39, P < 0.001, n = 137). The response in OM processing to clearfell harvesting differed between years and among benthic habitats. In coarse gravel habitat, there was a significant decrease in rates of cellulose decomposition potential in the 2nd and 4th year after harvesting, and a significant decrease in bacterial carbon production in the 3rd year after harvesting. However, we found a significant increase in rates of bacterial carbon production of fine sediment habitat in the 2nd and 4th year after harvesting. The contrasting response of OM processing between habitats indicates that habitat-specific changes occur after clearfell harvesting, which inhibit attempts to quantitatively predict downstream cumulative effects. Scaling up the habitat-specific responses will not only require estimates of the relative abundances of the distinct habitats, but may also require research into how different spatial configurations of habitats may affect reach- and catchment-scale estimates of OM processing. [ABSTRACT FROM AUTHOR]

Abstract: The distribution of hollow-using fauna is frequently related to forest type. If hollow occurrence varies with forest type, the use of generic prescriptions for managing the hollow resource may be inappropriate. This study examined the relationship between the occurrence and abundance of tree hollows and site and tree attributes in wet and dry Eucalyptus obliqua forest in Tasmania, Australia. A total of 388 trees at 39 sites were examined before and after being felled. Evidence of invertebrate damage contributing to hollow formation was more common in wet forest than either dry or damp forest. Evidence of hollow formation by fire and fungi was more prevalent in drier than wetter forest. There was no difference among forest types in the proportion of hollows showing evidence of limb breakage. Examination of the site and tree factors related to hollow presence and abundance was done using Classification Trees, Random Forests and generalised linear models. The variables found to be most practical for predicting hollow occurrence were the number of hollows observed before the tree was felled, tree diameter and the amount of dead wood in the canopy. Tree age, an important variable to consider when planning harvest rotations, was strongly associated with hollow presence but had less bearing on hollow abundance. The size of hollows that were found in a tree was related to greater senescence. Although significantly more hollows of all sizes were found in wet forest than either dry or damp forest, the age at which trees began to produce hollows was similar among the different forest types. The models predicted that trees needed to be at least 100 years old before they are likely to contain a hollow and that medium-sized hollows rarely occur in trees younger than 140 years old. Trees grow slightly more slowly in dry forest than wet which means that smaller diameter trees were found to contain hollows in dry forest than wet and that even the largest trees may not contain large hollows in wet forest. Despite this, no differentiation between the forest types was found in the predictive models. It is recommended that trees retained for faunal habitat be at least 100cm in diameter. [Copyright &y& Elsevier]

The use of predictive habitat distribution models by land managers in the conservation management of threatened species is increasing. Few models, however, are subsequently field-checked and evaluated. This study evaluates the statistical strength and usefulness for conservation purposes of three predictive habitat models developed for a threatened stag beetle, Hoplogonus simsoni, found in the wet eucalypt forests and mixed/rainforests of north-east Tasmania. The relationship between various environmental variables for which spatial (GIS) information was available and the density, frequency of occurrence and presence/absence of the species was investigated using generalised linear modelling. Models developed were coupled with the GIS data to develop maps of predicted occurrence within the species’ range, grouped into categories of habitat quality. The models found that altitude, aspect, slope, distance to nearest stream and overstorey tree height were significantly associated with the occurrence of the species. Evaluation of the statistical strength of the models with independent data of species’ occurrence collected at 95 sites found that the density model performed poorly with little correlation between predicted and observed densities of the species. The frequency of occurrence model, however, showed a moderate ability to predict both species’ abundance and presence/absence. The presence/absence model had a similar discriminatory ability in predicting presence or absence of H. simsoni, but also showed some potential as an indirect predictor of species’ abundance. Assuming a correlation between relative abundance and habitat quality, the frequency of occurrence predictive model appeared to be the better and more direct discriminator of high quality habitat relative to the other models. The value of species’ habitat models and the need to evaluate their utility in the development of conservation strategies are discussed. [Copyright &y& Elsevier]