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Understanding the effects of logging and fire on forest soil communities is integral to our knowledge of forest ecology and effective resource management. The resulting changes in soil biota have substantial impacts on forest succession and associated ecosystem processes. We quantified bacterial and fungal abundance, diversity and community composition across a logging and burn severity gradient, approximately one month after fire, in temperate wet eucalypt forests in Tasmania, Australia. Using amplicon sequencing and real‐time quantitative PCR of the bacterial 16S rRNA gene and fungal ITS1 region, we demonstrate that (i) burn severity is a strong driver of soil microbial community composition, (ii) logging and high severity burning substantially reduce the biomass and diversity of soil bacteria and fungi, and (iii) the impacts of logging and burning on soil microbial communities are largely restricted to the top 10 cm of soil, with weak impacts on the subsoil. The impacts of disturbance on microbial community composition are greater than the effects of site‐to‐site edaphic differences. Fire also drives more divergence in community composition than logging alone. Key microbial taxa driving differences in severely burnt soils include bacterial genera implicated in plant‐growth promotion and producing antifungal compounds as well as saprotrophic fungi that are also capable of forming ectomycorrhizal associations. Our research suggests that low‐moderate severity burns are important for maintaining diversity and biomass in soil microbial communities but having a range of burn severities across a site contributes to the overall diversity of habitat conditions providing for both microbial and plant diversity. [ABSTRACT FROM AUTHOR]

Tree hollows provide critical habitat for many species worldwide. The conservation of hollow-bearing trees presents a particular challenge for forest managers, partly due to difficulties in predicting their occurrence across a landscape. We trialled a novel approach for assessing relative hollow availability, by remotely estimating mature crown cover and senescence from aerial photographs in Tasmania, Australia. These estimates were tested against plot-based field assessments of actual occurrence of hollow-bearing trees. In dry forest we conducted ground-based surveys of hollows for all mature trees (>50 cm dbh) in 37 half-hectare plots. In wet forest, we conducted helicopter-based surveys of hollows for all mature trees in 45 oldgrowth plots (0.29-4.63 ha). Aerial photographs (1:10,000-1:25,000) were used to classify the senescence and cover of mature crowns in each plot. Regression analysis showed that, in dry forest, hollow-bearing tree densities were strongly related to the remote assessment of mature crown cover, with an 8% increase in variability explained if senescence was also included ( R = 0.50). In wet forest, mature crown cover alone was the best model ( R = 0.53 when outliers were removed). Assessing senescence was less important in dense wet forests than dry forest because trees take longer to form mature-shaped crowns and so mature-shaped crowns are more likely to have hollows. These results suggest that, with skilled photo-interpretation, aerial photographs can be useful for remotely assessing the relative density of hollow-bearing trees. This approach has the potential to greatly improve conservation planning for hollows and hollow-dependent fauna. [ABSTRACT FROM AUTHOR]

Abstract: The Warra Silvicultural Systems Trial (SST) in Tasmania, Australia provides a framework for investigating the responses of beetles (Order: Coleoptera) to three alternative systems in lowland wet eucalypt forest: aggregated retention; dispersed retention; and understorey islands retained in clearfelled areas. Beetles from three families known to be sensitive to forest management, the families Carabidae (ground-beetles), Curculionidae (weevils) and Leiodidae (fungus-beetles), were collected with pitfall traps prior to harvest, and in the first and third years post-harvest. The retained aggregates in the aggregated retention system maintained beetle assemblages reasonably typical of mature forests, at least in these early years following harvesting. These aggregates appear to provide a stable habitat, with similar species composition in the first and third years post-harvest. In contrast, the harvested areas of the aggregated retention system contained low numbers of beetle species affiliated with mature forest, as did the understorey islands and the dispersed retention system. Relative to clearfelling, all alternative silvicultural systems appeared to be of some benefit to beetles affiliated with mature forest, but aggregated retention retained far greater numbers of these beetles compared to the other systems in Tasmanian wet eucalypt forest. [Copyright &y& Elsevier]

• Bacterial communities in burnt soils recover lost abundance and diversity over time. • Logging and burn impacts on fungal abundance and diversity persist. • Both beneficial and antagonistic microbes negatively impacted by burning. • A range of burn severities help promote diverse soil communities post-logging. Globally, forest ecosystems are increasingly impacted by natural and anthropogenic disturbances including fire, timber harvesting and land clearance. Understanding how soil bacteria and fungi are impacted by logging and burning is important for resource management, as these microbiota underpin many essential ecosystem processes such as nutrient cycling and soil formation. Using amplicon sequencing and qPCR of the bacterial 16S rRNA gene and fungal ITS1 region, we quantified the abundance, diversity, and composition of soil bacterial and fungal communities in undisturbed forest and adjacent logged and burnt sites, which included a mosaic of burning severities (unburnt, low severity and high severity burns). Our study was conducted over a 12-month time series post-burn, in the temperate wet eucalypt forests of Tasmania, Australia. We found that over this 12-month period i) after high severity burns, total abundance and diversity returned to pre-disturbance levels in bacterial communities but not in fungal communities and ii) for each disturbance severity, the composition of bacterial communities became more similar to the undisturbed reference communities over time, while fungal communities did not. We also characterised the succession of disturbance responsive taxa in logged and burnt communities, with the relative dominance of copiotrophic bacteria and fire-associated Ascomycota fungi shifting towards oligotrophic bacteria and fire-associated Basidiomycota fungi by 12-months. Further, we highlight specific taxa that respond positively or negatively to the impacts of fire disturbance and discuss the ecological implications of our findings for forest management. [ABSTRACT FROM AUTHOR]

Abstract We derive a formula for correcting the weight of food eaten by an animal for natural weight loss (or gain) of the food, such as through moisture loss and food respiration. The formula is derived using a differential equation to model the loss in fresh weight based on a constant consumption rate and assumptions about the form of the function for weight loss over time of the aliquot. The standard formula is shown to over-estimate the weight of eaten food compared to our theoretically derived formula. This over-estimation is negligible (< 0.2%) for moisture loss below about 10% but increases sharply to 8% when moisture loss is 50%. We illustrate the application of these two formulae using a laboratory study of consumption rate by larvae of a phytophagous insect: the Tasmanian eucalyptus leaf beetle, Chrysophtharta bimaculata (Olivier) (Coleoptera: Chrysomelidae). [ABSTRACT FROM AUTHOR]

Abstract The native Eucalyptus leaf beetle Chrysophtharta bimaculata (Olivier) (Coleoptera: Chrysomelidae) has become a pest of the introduced, plantation species, Eucalyptus nitens Maiden in Tasmania, Australia. However, in the field it prefers to oviposit on the Tasmanian native species, E. regnans F. Muell. This laboratory study found that the performance of C. bimaculata larvae was superior on foliage of E. nitens compared with E. regnans . Larval development was 4 days shorter on E. nitens than on E. regnans foliage. Total food consumption per larva and relative consumption rates were about 30% lower while relative growth rates and weight of emergent adults were more than 25% higher on E. nitens than E. regnans . Efficiency of conversion (ECI) of fresh food into larval wet weight was 0.26 on E. nitens compared with 0.14 on E. regnans . Mortality of larvae feeding on E. nitens (23%) was only one third of that on E. regnans (69%), a result of high first instar mortality on E. regnans . Although the amount of foliage consumed per larva was lower on E. nitens (0.23 g vs 0.32 g), the differential mortality meant that the amount of E. nitens consumed per egg batch was 60% more than that of E. regnans . If these results occurred in the field, then the same monitored population of C. bimaculata eggs may result in heavier defoliation of plantation E. nitens than of E. regnans . These data show that the reported oviposition preference of C. bimaculata for E. regnans in the field cannot be explained by selection of host factors related to superior larval performance. [ABSTRACT FROM AUTHOR]

• Large, old trees with hollows provide important habitat for hollow-using species. • Retention forestry can help retain habitat trees in harvested areas. • Aggregated retention retained more habitat trees than other silvicultural systems. • Aerial and ground-based surveys gave similar estimates of habitat tree abundance. • Helicopter surveys are a rapid, cost-effective approach for post-harvest assessment. Habitat trees (mature live and dead trees with hollows) are a keystone habitat in Australian eucalypt forests where tree hollows typically occur in large, old trees. These trees provide potential habitat for hollow-using birds, bats and arboreal marsupials, including many threatened species. Habitat trees may be felled during forest harvesting and can also be negatively affected by wildfires. Shortages of habitat trees in harvesting landscapes can be a limiting factor for populations of hollow-using vertebrates. Retention forestry systems are expected to retain a greater number of habitat trees within sites than traditional clearcutting silviculture, but there is a need to quantify how the pattern of retention (dispersed trees vs. retained clumps) will affect the numbers and types of trees retained. The method of assessment (ground-based vs. aerial surveys) may influence the estimated numbers of habitat trees. We investigated habitat tree retention at the Warra Silvicultural Systems Trial in Southern Tasmania, Australia. This trial was instrumental in developing alternatives to clearcutting in tall, wet, old-growth eucalypt forests. Our research has two objectives. Objective 1 is to assess the numbers of habitat trees retained in various alternatives to clearcutting by comparing: unlogged control areas, 0.5–1 ha clumps retained within a harvested matrix (aggregated retention), trees scattered throughout the harvested area (dispersed retention), and small ~0.08 ha machinery exclusion zones where trees were retained if they were not of commercial value (clearcutting with understorey islands). Objective 2 is to compare ground-based to aerial, helicopter-based, assessment of large live and dead trees. Although low replication of harvest treatments precluded statistical comparison of silvicultural systems, the results, based on 1,260 trees, were clear. Of the various alternatives to clearcutting, aggregated retention retained the greatest proportion of all classes of habitat trees, primarily because of higher retention targets, but possibly also because of greater survival with reduced wind exposure in aggregates. Substantially fewer habitat trees were retained with dispersed retention, and virtually none with understorey islands in clearcutting. Aerial and ground-based assessment methods provided similar estimates of numbers of trees with visible hollows in aggregates and understorey islands (R2 = 0.95). Choice of method for future studies should consider available resources and objectives, since there were advantages and disadvantages of each approach. In conclusion, aggregated retention was found to be the preferred silvicultural system for retaining habitat trees within sites for hollow-using vertebrates, and helicopter surveys provide a rapid alternative to traditional ground-based assessment. [ABSTRACT FROM AUTHOR]

Background: Variable retention harvesting using aggregated retention (ARN) has been applied in some Tasmanian wet eucalypt forests for > 15 years. Implementation of ARN in Tasmania differs from most other regions, as forest influence (or the proximity of harvested areas to long-term retention) is primarily used to distinguish ARN from clearfelling rather than retention level, and broadcast burning is used as a regeneration treatment, resulting in a preference for edge aggregates instead of isolated retained islands. Clear emphasis on site-level retention of biological legacies and forest influence to facilitate re-establishment of mature forest species ensures that ARN coupes achieve the ecological objectives associated with retention forestry. Results: Spatial and survey data collected from operational ARN coupes illustrates the development of this silvicultural practice over time and allows comparisons with conventional clearfelling. Over 90% of ARN coupes have met the forest influence target of > 50%. The number of ARN coupes harvested per year has varied, but mean retention levels (29%) and the mean area harvested per coupe (24 ha) have remained the same. Forest influence in ARN coupes has decreased over time, as have perimeter-to-area ratios, largely due to a decrease in the number of island aggregates. Although these measures of complexity have decreased, ARN coupes still have much greater forest influence, retention, and perimeter-to-area ratios when compared to conventional clearfell, burn and sow (CBS) coupes. The observed decrease in boundary complexity should facilitate regeneration burning in ARN coupes, although no increase in the proportion of burnt seedbed was observed. The proportion of burnt seedbed is strongly correlated with eucalypt seedling stocking and density in ARN coupes, and these attributes were all significantly lower in recent ARN coupes compared to clearfells. These differences appear to be due to achieving better burns in recent CBS coupes, rather than poorer ones in ARN coupes. Conclusions: Although the area that can feasibly be harvested by ARN is limited by the requirement for regeneration burning, ARN provides clear biodiversity benefits and satisfactory silvicultural outcomes and is now firmly embedded as a viable alternative to clearfelling in Tasmanian wet eucalypt forests. [ABSTRACT FROM AUTHOR]