Forest health and biosecurity in a changing world

Australia’s forest industry faces significant challenges to ensure it is prepared to meet existing, emerging and new forest health and biosecurity threats in a changing world. Increasing volumes and diversification of trade and travel are escalating the risk of exotic pests establishing in Australia, and climate change is predicted to affect host susceptibility to pests and pathogens and increase the frequency and intensity of droughts and fires, which can cause significant forest losses. Yet, as these risks are increasing, Australia’s technical capacity in forest health and biosecurity is declining. Together, this substantially weakens our ability to identify and respond to biosecurity threats, solve emerging forest health issues and manage ongoing pest risks – all crucial for sustainable forest productivity and market access. The papers presented in this themed edition of Australian Forestry address key issues relating to these broad topics.

Changing climate

Increases in drought and heatwaves, and drought-driven pest outbreaks, have resulted in large-scale forest mortality worldwide (Raffa et al. 2008; Allen et al. 2010). In Australia, climate-change predictions suggest a greater intensity and severity of droughts and heatwaves, likely leading to increased tree mortality in plantations (Pinkard et al. 2014). The interactive effects of climate change, including increasing host susceptibility and expanding pest distribution and abundance, are likely to amplify impacts (Pinkard et al. 2014). Forest managers need to prepare to adapt to a changing climate (Pinkard et al. 2014), with adaptation to the effects of climate change recently identified as a priority for governments, industry and communities in Australia (CSIRO 2022).

In this issue, Carnegie, Kathuria et al. (2022) used two decades of forest health surveillance data to develop a model of the risk of drought-induced mortality in Pinus radiata D.Don plantations in New South Wales, Australia, under current and future climates. The study produced geographical information system maps at 100 m resolution, providing managers with operational-scale outputs to manage potential drought impacts, for example by using targeted thinning and lower stocking and by planting drought-tolerant genotypes. Under climate change, weather extremes such as high rainfall could also increase the impacts of pathogens, such as dothistroma needle blight in P. radiata plantations (Pinkard et al. 2014). Ensuring that optimal management strategies are in place is essential for mitigating future impacts. In this issue, Carnegie and Kathuria (2022) report on a trial illustrating the effectiveness of the aerial application of cuprous oxide in controlling dothistroma needle blight. This research is timely given the severe outbreaks of dothistroma needle blight in New South Wales and Victoria observed in 2022 following higher-than-average rainfall, with almost three times the area requiring control compared with previous years (A. Carnegie, pers. obs., 2022; D. Smith, pers. comm., 2022).

Increasing pest risk

Risks to Australia’s native forests and plantations from exotic pests are increasing (Lawson et al. 2018). Despite strong biosecurity measures, on average two new pests establish each year in Australian forests and about 20% have moderate-to-high impacts (Nahrung and Carnegie 2020). Many of these pests were not predicted in biosecurity risk analyses (Carnegie and Nahrung 2019), and our current risk assessment methods may not adequately capture future threats (Nahrung and Carnegie 2022). Further, Australia’s eradication success in forestry is less than half the world average (Carnegie and Nahrung 2019).

The aim of the National Forest Biosecurity Surveillance Program, scheduled to commence in late 2022, is to improve early detection of forest pests to increase the likelihood of successful eradication (Carnegie, Tovar et al. 2022). The presence of amenity trees in urban areas may facilitate forest pest invasions (Paap et al. 2017), so public engagement – one of the pillars of the new program – is paramount across the biosecurity continuum. The public is already responsible for the second-highest rate of new post-border forest pest detections in Australia (Carnegie and Nahrung 2019) and, as reported in this issue, stakeholder biosecurity awareness and training led to the recent detection of an exotic disease in a P. radiata production nursery in New South Wales (Carnegie, Callaghan et al. 2022). Although the subsequent response was efficient and effective, it led to questions about whether the industry is fully prepared for a significant exotic pest threat like pine pitch canker, with the pine pitch canker response plan now more than two decades old. Further work is required to better understand the risks, pathways and potential management strategies of exotic pests in Australian forests.

Our understanding has improved of forest pest threats at each invasion stage (prediction, arrival, establishment, spread and impact) and corresponding pre-border, border and post-border biosecurity measures through a series of analyses across the biosecurity continuum (Carnegie and Nahrung 2019; Nahrung and Carnegie 2020, 2021, 2022). Asian- and European-origin species account for two-thirds of non-native forest pests established in Australia and are equivalently represented numerically, temporally and compositionally (Nahrung and Carnegie 2020). However, those originating in Asia feed on a broader range of hosts and have established in northern Australia more often than species from elsewhere, presumably reflecting climatic similarity, geographic proximity and host plant suitability. Over 95% of the non-native forest pests in Australia are invasive elsewhere in the world (Nahrung and Carnegie 2020; Horwood et al. 2022), illustrating the role of ‘bridgehead’ populations in invasions (Nahrung and Carnegie 2021, 2022) and the importance of shared biosecurity responsibility between countries (Ricciardi et al. 2021; Nahrung et al. 2022). Tran et al. (2022) highlight a recent example of this kind of invasion pattern through the Asian-origin and highly polyphagous granulate ambrosia beetle, Xylosandrus crassiusculus. They show that there have been at least two independent invasions of this beetle in Australia, with a potentially related introduction to New Zealand.

Looking beyond our shores is a critical aspect of Australia’s response to forest health threats, with international engagement key to developing biosecurity capacity beyond borders. Here, Australia already has experience, detailed in this issue by Healey et al. (2022), who review Australia’s track record of supporting research into pests and diseases in eucalypt and acacia plantations established across Southeast Asia. This work is important development support for Australia’s neighbours and it also contributes to the understanding of these key Australian genera and their health risks, builds critical sentinel surveillance capacity for protecting Australia’s forests from new threats, and creates a neighbourhood of biosecurity-capable countries with the capacity for biosecurity risk management and coordination essential in this trade-rich region. Healey et al. (2022) also find that there has been a gap in attention on the social (economic, policy, governance and cultural practices) aspects of research and capacity building in forest biosecurity in the region. Critically, Australia will be unable to contribute as strongly to building regional capability if our own capacity is diminished.

Loss of capacity is described in this issue by Horwood et al. (2022), who review insect pests associated with timber-in-service and their management and future risks. They also highlight that the forest industry (growers and processors) has no recourse on how exotic pests of timber-in-service are responded to when detected. Furthermore, repealing legislation to protect timber from insect pests and recent changes to state government programs for the West Indian drywood termite, the world’s most invasive termite species, have likely increased the risk to timber-in-service. Also in this issue, Haigh et al. (2022) summarise our understanding of West Indian drywood termite and outline the research needed to improve its detection and management following the cessation of state government management programs. These papers highlight the impacts of timber-in-service pests, yet there is currently no mechanism for forest industry involvement following their detection under national biosecurity mechanisms because they do not meet the definition of an ‘emergency plant pest’ in the Emergency Plant Pest Response Deed (Plant Health Australia 2022).

Declining capacity

Australia has a strong track record in successfully responding to and managing established and new forest health threats. Examples include extensive research and development in a biological control program for sirex woodwasp (Bedding 1993; Carnegie and Bashford 2012), development of an integrated pest management program for chrysomelid leaf beetles (Candy et al. 1992; Elliott et al. 1992), and research to quantify the impact of the Monterey pine aphid and introduce a biocontrol agent (May and Carlyle 2003; Kimber et al. 2010). Many of these successes brought together industry practitioners with multidisciplinary research teams (Pinkard et al. 2014).

Hardwood plantation expansion in the 1990s (Gerrand et al. 2003) saw an increase in entomologists and pathologists employed by government agencies to conduct forest health surveillance and research on emerging issues (Carnegie 2008). However, with the privatisation of plantation estates (Gerrand et al. 2003) and the re-prioritisation of previous ‘public good’ research and service, there has been a significant reduction in structured and systematic forest health surveillance in Australia (Carnegie et al. 2018) and a subsequent decline in technical capacity.

This has mirrored declines in plantation research capacity (Australian Forest Product Association 2013), access to taxonomic expertise (Weaver 2017), forest research capacity (Turner and Lambert 2012), and plant pathology and entomology capacity more broadly (Howie 2012), such that Australia’s forest health and biosecurity technical expertise is vanishing fast (Figure 1). Two decades ago, almost all state primary-industry departments and state-owned growers had at least one senior forest entomologist and senior forest pathologist, with several junior staff-in-training. This was true also for the Australian Government, including CSIRO, and there were also nationally recognised forest health experts in several universities. Since 2010, however, many retiring entomologists and pathologists have not been replaced, CSIRO disbanded its forest health section, the long-running Forestry Cooperative Research Centre (CRC) program ceased, universities significantly scaled back undergraduate training in entomology and pathology, and some state governments moved away from providing operational support to the forest industry. Furthermore, universities placed increasing emphasis on ‘research excellence’ focused on publication output and international benchmarks, with operational research that leads to improved industry practices becoming less appealing to university researchers (Keenan 2010).

Figure 1. Decline in technical expertise in forest health and biosecurity in Australia, as represented by membership on the peak national technical expert committee: Research Working Group 7 (2000–2010), Subcommittee on National Forest Health (2011–2015), Forest Health and Biosecurity Subcommittee (2016–present). Projected beyond 2022 (dashed line) based on current personnel, likely future retirements and no new recruitment. We acknowledge that not all experts in Australia are members of this committee, but membership is representative of the capacity of technical expertise actively engaged in forest health and biosecurity at an operational and policy level

An ongoing decline in Australia’s technical expertise will lead to a collapse in our ability to promptly detect change and risks to our native forests and plantations, potentially threatening the Australian forest industry’s sustainability, productivity and trading ability. Many states once had formal forest health surveillance programs – primarily of state-owned plantation estates – with forest entomologists and pathologists actively in the field to detect threats (Carnegie 2008). Forest health surveillance is an important component of internationally recognised forest management certification standards (Carnegie et al. 2018), and it enables prompt diagnosis of causal agents and the provision of recommendations for reducing impacts and monitoring to evaluate the remedial actions undertaken (Phillips 2008). The aim of forest health surveillance is to detect outbreaks of pests and diseases at an early stage while damage is still confined to small areas and before severe adverse impacts occur (Carnegie 2008).

General surveillance in urban areas for the early detection of exotic pests (by local councils, arborists and public groups) is also vital (Carnegie and Nahrung 2019; Carnegie, Tovar et al. 2022), but it requires specialised diagnostic capacity to follow up reports and highly trained technical experts in the field to respond to detections with surveillance and monitoring and to participate in eradication and containment if required. General surveillance is covered, in part, in the new National Forest Biosecurity Surveillance Program (Carnegie, Tovar et al. 2022), but sustainable funding for adequate technical expertise is lacking.

Rebuilding capacity – a shared responsibility

The sharp shift away from investing in research capacity in surveillance and damage assessment over the past decade (FWPA 2020) runs counter to the need to strengthen capacity in the face of increasing risks from exotic pests and climate change. To address this, Forest and Wood Products Australia developed an investment plan to guide collaborative research, development and extension in forest health and biosecurity. The Damage Agents Investment Plan (FWPA 2020) has a strong focus on developing tools and systems at the national level to support the industry in forest health surveillance. The shift towards nationally supported systems should accelerate industry access to applications using newly developed technologies and more accurate risk models by detecting and observing events at the subnational and national scales.

Australia needs to significantly upscale its current biosecurity system to cope with increasing risks, and it needs to invest in transformational technologies to increase efficiencies and effectiveness (CSIRO 2020). A recent (2022) review of the Damage Agents Investment Plan highlighted this growing need for transformational technologies, such as remote sensing and artificial intelligence to optimise forest health surveillance (e.g. Stone and Mohammed 2017) and to improve pest detection and diagnostic systems with genomic biosurveillance technologies (e.g. Hamelin and Roe 2020). With the decline in technical capacity, such technologies are essential for industry to effectively and efficiently detect and map damage in plantations and to detect and diagnose pests quickly and accurately during forest health and biosecurity surveillance. Early detection and accurate diagnosis are key for effective intervention (e.g. eradication or pest management). New research in Australia in these areas shows promise for biosecurity surveillance (Carnegie et al. under review) and pathogen diagnostics (Trollip et al. 2022) but does not replace the need for experts nor compensate for the ‘taxonomic impediment’ that can significantly hamper the ability to respond to new invasions (Ricciardi et al. 2021).

Our ability to respond to forest pest threats is predicated primarily on funding for technical experts. There are opportunities for industry to invest in the training of postgraduate students, including through the purpose-designed frameworks of Australian Research Council Training Centres and CRC programs in partnership with universities, but a whole-of-industry and government partnership approach is needed to maximise returns on investment in postgraduate students by providing ongoing professional positions, which will reverse declining capacity. Australia’s forest industry has relied heavily on PhD students to conduct forest health research, particularly through Forestry CRC models between 1991 and 2011. However, very few PhD students who completed their studies in forest health or biosecurity in the past two decades are currently employed in this discipline because few positions are available. Traditionally, and for larger industries like grains and horticulture, biosecurity scientists are employed predominantly by state agencies, where their expertise can be accessed and leveraged by the government and multiple industries. For the forest industry, this is now only the case in some states. Moreover, there are no forest health experts in some states nor evidence of recent succession planning in any states except Queensland.¹

Since 1999, the forest industry in Western Australia has jointly funded its own forest health researcher. A decade after South Australia’s previous state technical expert retired, the forest industry in the Green Triangle employed its own technical-expert-in-training, funded by multiple growers. A new levy was recently approved by the forest industry to fund the National Forest Biosecurity Surveillance Program to improve early detection at national borders (Carnegie, Tovar et al. 2022) and to fund a Forest Biosecurity Manager role in the Australian Forest Products Association. However, there is potential for a partnership model between regional forest industry groups and state governments to share responsibility for ensuring ongoing capacity that will benefit both – that is, technical experts who can provide operational needs and policy advice for plantations, conservation and native production forests and amenity trees. Essential to this is experiential learning, such that knowledge and experience from current technical experts are passed on. There is an urgent need to ensure that Australia will have access to forest health and biosecurity technical experts in the future to safeguard Australia’s forests – public and private, urban, commercial, multiple-use and conservation – from the compounding predicted risks of climate change and the increasing prevalence of exotic pests.

Notes

¹ As this editorial was going to press, the NSW Department of Primary Industries had secured a position for a recent PhD graduate as part of succession planning in forest health and biosecurity technical expertise.