ABSTRACT Loss of arboreal connectivity can be detrimental to many forest-dependent species. Mitigation efforts focus on restoring opportunities for movement of arboreal mammals via rope bridges and other crossing aides and structures. These have been tested for major roads, but there is limited research regarding the effectiveness of rope bridges as road crossing aids for arboreal mammals in forested areas, subject to timber harvesting. Here we present a study where single rope bridges (100 mm in diameter) were placed in managed forests of the Central Highlands of Victoria, Australia. These were monitored using remote cameras for a period of up to 30 months. We recorded bridge visit data to assess rope bridge use. We found that range of species utilising the bridges, with passerine birds making up 68% of our observations. Both volant and non-volant mammals were also observed, including the first report of the endangered southern greater glider (Petauroides volans) utilising a rope bridge. Our results show that single rope bridges over forest roads can aid faunal occurrence and movement around and across forest roads.

ABSTRACT Determining the climatic requirements of tree species is essential for their effective management under climate change. Ideally this requires analysis of both native and introduced occurrences. A 2023 ‘TreeGOER’ paper has estimated the climatic and edaphic requirements of 48 129 tree species. Here we show how the climatically suitable areas for any of these species can be mapped on a global five-minute resolution grid using freely available resources. For nine eucalypt species, widely planted outside Australia, we compare the TreeGOER-based maps with those based on previous ‘climatic mapping’ analyses of climatically suitable areas. The two methods identify some similar climatically suitable areas, but the comparisons also highlight major differences and some limitations of both methods. Care is particularly needed in using ex situ data from the Global Biodiversity Information Facility. Greater availability of results from trials outside species native distributions would improve both TreeGOER and ‘climatic mapping’ analyses. The development of a global tree trial database would facilitate these improvements.

ABSTRACT Corymbia citriodora subsp. citriodora has a long history of cultivation as a multipurpose tree in China and many other countries in Southeast and South Asia. Despite this history and longstanding interest in the species, published studies examining genetic variation among and/or within provenances/seed sources are scarce. Recognising this and to initiate an improvement program for this species, a field trial was established in southern coastal China in 2015 with 171 open-pollinated single mother-tree family seedlots representing five natural-stand seed sources in Australia and six planted seed sources in China. Large significant variation was found among seed sources for pest and disease resistance, survival, growth and stem form up to age 81 months. Australian seed sources were generally superior to Chinese ones for most traits. Phenotypic correlations among traits, at both the individual tree and seed-source mean levels, were favourable, with the strongest individual tree correlations found between disease susceptibility at 10 months and various tree growth traits. Overall, the variation observed in this field trial indicates the potential gains in this species from seed-source selection and ongoing breeding.

ABSTRACT The radiata pine tree improvement program in Australia estimates breeding values for selection criteria traits (SCTs) such as diameter at breast height and height, as measured in progeny trials. The data in each trial are standardised so that estimated breeding values (EBVs) are expressed in units of additive genetic standard deviations. EBVs for harvest-age breeding objective traits (BOTs), such as stand volume mean annual increment (VMAI), are predicted from the SCT EBVs and expressed in measurement units. BOTs are not routinely measured in progeny trials because it would prolong the generation interval. However, the slope of the relationship between VMAI and BOT EBV provides an estimate of the scale of VMAI EBVs. This slope was estimated using 26 block-plot realised-gain trials with stand total produced basal area (TPBA) measurements near age ten years and 11 trials with final VMAI measurements between 15 and 25 years extrapolated to a harvest age of 25. In all trials, EBVs were positively correlated with growth, demonstrating substantial realised genetic gains. At age ten years, on average, one standard deviation of BOT EBV corresponded to a realised gain in TPBA of 3.7 m2 ha−1 and an additive coefficient of variation (CVA) of 11.2%. At the harvest age of 25 years, one standard deviation in EBV corresponded on average to realised gains in VMAI of 4.2 m3 ha−1 y−1 and a CVA of 15.0%. Methods for incorporating estimated genetic gains into growth and yield modelling and forest valuations are discussed.

ABSTRACT Drought is a regular feature of Australian landscapes, and its intensity and frequency are likely to increase in a changing climate. Land managers are grappling with managing the impacts of drought, with large-scale die-offs occurring more frequently in forests globally. Drought-induced tree mortality has caused major impacts in Pinus radiata plantations in New South Wales, Australia, with extended drought, heatwaves and pest and disease attacks all recognised as predisposing, inciting or contributing factors. The extent and severity of drought-induced tree mortality has been mapped across the Pinus plantation estate in New South Wales annually since 1996. In this study, we used this long-term empirical data to develop a model of drought risk for P. radiata plantations. Using random forest, we identified site index, annual temperature, annual rainfall, elevation and increasing number of hot days (above 20°C and 35°C) as the influencing variables associated with drought-induced tree mortality. We then used this model to look at the risk of drought-induced tree mortality under climate-change scenarios in 2050 and 2070. Although forest managers already understand the drought risk in their estates, we developed an empirical model and produced GIS layers at high resolution (100 m) to assist in more accurately and effectively managing drought. The accuracy and precision of our model (overall accuracy 89.2%, kappa 0.75) enables forest managers to include it in their decision-making in the management of the potential impacts of drought on the current plantation estate (e.g. via modified silvicultural regimes) as well as in the future (e.g. modified silvicultural regimes or planting drought-tolerant genotypes).

ABSTRACT Early detection of exotic pests is key to a timely response for enabling options for eradication and future management. It is widely recognised that engaging the public and industry in general surveillance significantly increases the chance of detecting newly arrived pests and pathogens. Once a new pest or pathogen is detected, Australia has guidelines to follow via the Emergency Plant Pest Response Deed and PLANTPLAN. This paper describes the detection of unusual symptoms in a Pinus radiata production nursery in New South Wales, Australia, and the subsequent response. The unusual symptoms were detected in early January 2021 by nursery staff and reported immediately to biosecurity authorities. The nursery was placed under quarantine as a precaution. Within five weeks, Fusarium commune was diagnosed from the samples, a known pathogen of conifers not previously recorded in Australia. Formal biosecurity processes were enacted immediately to determine whether the pathogen was an emergency plant pest and whether eradication was necessary and technically feasible. Quarantine and movement restrictions continued, such that no seedlings could leave the site other than for ongoing diagnosis and under biosecure protocols. Tracing was conducted to determine the distribution of the pathogen and a potential source, including ongoing sampling in production nurseries, diagnosis of planting media and seed, and diagnosis of root and soil eDNA samples collected in previous years. Fusarium commune was recovered at a very low frequency from two nurseries, primarily in association with healthy seedlings. Root and soil samples collected from nurseries and plantations between 2019 and 2020 tested negative for the presence of F. commune using F. commune-specific primers. Pathogenicity tests revealed that F. commune did not cause wilting or significant disease on tested seedlings. Overall, evidence suggested that F. commune did not pose a serious threat to the P. radiata industry. The Consultative Committee on Emergency Plant Pests determined that F. commune was not a significant pathogen and that no further action was warranted. The affected nursery was allowed to resume operations in mid-May 2021, in time for the winter planting season. Here we discuss the lessons from this response, including the benefits of a quick and timely response, cross-institutional collaboration, the potential threat to the forest industry, and the need to encourage greater general surveillance. These lessons can help in the event of an incursion of a serious pathogen such as F. circinatum (pine pitch canker).

ABSTRACT ‘Timber-in-service’ consists of tree components prepared for use in building and carpentry and other wooden infrastructure such as bridges, pylons and power poles. About 70% of timber used in Australia goes into building and construction and 15–20% goes into furniture, and 50 000 electricity poles are produced annually. Timber-in-service pests are a threat to such material throughout its service life. In this review, we identify native and non-native insects associated with timber-in-service in Australia and their impacts and current management. Border and post-biosecurity interception data of insects associated with wood and wood products are analysed to assess future risks, and key biosecurity threats (i.e. exotic timber-in-service pests) are identified. We review current biosecurity systems and processes related to the mitigation of potential threats to timber-in-service and provide examples of how detections of exotic timber-in-service pests are managed in Australia. We conclude with recommendations on how to improve biosecurity and management of timber-in-service pests.

ABSTRACT Although studies in mainland states of Australia and overseas show that the conversion of native forests to plantations can reduce carbon (C) stocks in soils, no studies have been undertaken in Tasmania to assess how plantations affect soil C stocks. To address this knowledge gap, we compared soil C concentrations and C stocks to 30 cm depth in native ‘mixed’ eucalypt forests and adjacent Eucalyptus nitens plantations on Ferrosols in north-west Tasmania, using a factorial sampling strategy. Mean soil C and nitrogen (N) concentrations were significantly lower in plantations than in mixed forests; however, because the soils in plantations had higher bulk density, mean soil C stocks under the two treatments (114 Mg ha−1 and 116 Mg ha−1, respectively) were not significantly different. It is concluded that machine removal of 5–6 cm of topsoil into windrows during land clearing for plantations would be sufficient to explain why C concentrations were lower in plantations than in mixed forests and that, apart from this physical effect of land preparation, 17–21 years of plantation growth on Ferrosols in north-west Tasmania has not significantly affected soil C stocks in mineral soil. This result can be partly explained by the ability of Ferrosols to form stable complexes between organic matter, sesquioxides and clays.

ABSTRACT Dead trees can occur throughout an urban forest and need to be managed. Standing dead trees that have been made ‘safe’ through regular inspection and the removal of unstable and decaying material are called ‘totem trees’ by Transport Canberra and City Services in Canberra, Australia. This paper is a pilot case study of totem trees in Canberra, employing an innovative mixed-methods approach, which includes silvicultural assessment, focal sampling, ad libitum sampling, in situ observation of evidence for fauna presence, and public questionnaires. It demonstrates that totem trees have significant habitat value because they provide perching, nesting, vocalisation, habitation and feeding sites for birds and arboreal mammals, as well as habitation and food for reptiles, insects and fungi. Totem trees with greater structural complexity appear to be preferred by fauna. The questionnaire findings, from park users and nearby park residents, indicate a generally positive attitude towards totem trees, with most participants perceiving them as valuable habitat for fauna and appreciating their aesthetic appeal. This highlights an important juxtaposition of management priorities: the need to balance structural complexity with providing safe trees. The findings of this study underscore the need to maintain and enlarge the totem tree population given their significant habitat value and social functions. Freestanding, structurally complex dead trees with numerous hollows, branches and bark should be prioritised for conservation. Additionally, the raising of public awareness is recommended to address any ongoing public uncertainty regarding the safety of totem trees.