Hostile environments, terminal habitat, and tomb trees: the impact of systemic failures to survey for mature-forest dependent species in the State forests of New South Wales

Species distributions and threats posed by intensive logging in NSW

Both the GGCS (Box 1) and YBGSE (Box 2) may occur wherever there are suitable habitat components (i.e. stands including HBTs) in the two CIFOAs under consideration in this paper. Thus, we show the distribution of these two species in relation to CIFOA boundaries and tenure based on over 30,000 Atlas of Living Australia (ALA) records for the GG and 25,000 records for the YBG (Fig. 1a, b). The extensive gap in the distribution of both species throughout the alpine region covered by the southern CIFOA largely coincides with a lack of, or limited tree cover, and with areas gazetted as National Park.

Logging is a key threat to arboreal marsupials (Eyre and Smith 1997; Lindenmayer et al. 2020) through depletion of large mature trees (McLean et al. 2015), and loss of canopy connectivity and denning/food resources that these provide (Kavanagh 1987; Kavanagh and Lambert 1990). Like the GGCS, the YBGSE prefers old growth forest containing a high abundance of HBTs, in comparison to regrowth forest or forest subject to selective logging rotations (Lindenmayer et al. 1999; Incoll et al. 2001). The YBGSE can persist in areas impacted by logging, provided that old trees are preserved within riparian zones and unlogged forest patches and corridors are retained adjacent to logged land (Goldingay and Kavanagh 1991, 1993; Kavanagh and Bamkin 1995; Eyre and Smith 1997; Kavanagh and Webb 1998), but occurrence decreases with increased logging intensity (Smith et al. 1994; Wormington et al. 2002; Eyre 2007).

Logging interacts with fire to compound the impact of bushfires on HBTs (Lindenmayer et al. 2012; McLean 2012). Thus, intensive logging of eucalypt forests makes them more likely to experience crown fire; and changes microclimates, stand structure and species composition (Lindenmayer et al. 2009; 2022a, 2022b; Price and Bradstock 2012; Taylor et al. 2014; Lindenmayer and Zylstra 2024). Such changes make these forests more prone to ignition and increased fire severity (Lindenmayer et al. 2009; Attiwill et al. 2014; Taylor et al. 2014; Wilson et al. 2018; Lindenmayer and Taylor 2020; Bowman et al. 2021; Furlaud et al. 2021; Lindenmayer et al. 2021; Zylstra et al. 2021; Lindenmayer and Zylstra 2024). HBTs are also threatened by post-fire salvage logging (Noss and Lindenmayer 2006; Lindenmayer et al. 2008; Wardell-Johnson et al. 2024). The threats posed to these once common, but now threatened species (see Lindenmayer et al. 2011a) are increasing. Therefore, their survival under climate disruption caused by global warming depends on effective and reliable survey linked to meaningful management outcomes. The CIFOA protocols appear to reflect this imperative.

Forestry operations and associated survey and conservation protocols for gliders

As at December 2023, CIFOA survey methodology and effort required that FCNSW detect all den trees in the operational area (and potentially within 100 m around it). The CIFOA provided (in conjunction with the definition of ‘den’), among other things, that a 50-m radius exclusion zone (i.e. 0.78 ha) was to be retained around any den tree identified in the broad area habitat search, or previously mapped or recorded. Thus, surveyors must look for, identify and record (among other things) ‘nest, roost or den trees’. A den (specifically in relation to Petaurus australis, Petaurus norfolcensis (Squirrel Glider), and Petauroides volans (collectively, gliders)) includes but is not limited to a tree-hollow, crevice, or fissure in a tree where a glider is seen entering or leaving.

According to the definition, entry or exit of a glider is an indicator of a den. However, it is not the only indicator and the definition does not restrict or qualify the indications that can be relied upon by a surveyor to reach a conclusion that it is likely that a given hollow, crevice, or fissure in a tree is used as a den site. The area within 100 m of the base net area of the area where a forestry operation will occur or is occurring, must be surveyed for den trees where it ‘is known or likely’ that they will exist there. Thus, forestry operations must not be conducted unless an effective den tree survey (among other surveys) is conducted within the whole of the operational area.

Den trees are a subset of the HBTs in a site. HBTs are defined by the EPA (Environment Protection Authority 2014) as dominant or co-dominant living trees with visible hollows, holes, or cavities or are likely to have them. Hollows are not always visible from the ground but may be apparent from the presence of rounded knotty growths, protuberances, or broken limbs, or where the top of the tree has broken off. While HBTs are any trees with hollows (including those suitable as nesting sites for small hollow requiring species (see Gibbons and Lindenmayer 2002), not all such trees are suitable as den sites for the GGCS and YBGSE. These species require large hollows that usually take at least 150 years to form (Box 1, 2).

In addition to safeguarding den trees and associated buffers, FCNSW was required (up until February 2024) to retain eight HBTs per ha, though can log up to the base of these trees. Under changes to EPA protocols (from 9 February 2024, as reviewed by Lindenmayer and Ashman (2024)), the 50-m exclusion zone around known recorded locations of glider dens remained but surveys were no longer required. Instead, loggers were then compelled to protect 14 HBTs per ha in high density glider areas and 12 per ha in low-density areas, as well as future HBTs. These requirements were again changed from 16 February 2024, under GGCS site specific biodiversity conditions (SSBCs) whereby FCNSW were then required to undertake nocturnal surveys for GGCS dens (in addition to previous requirements). On 27 May, the EPA amended the conditions to ensure FCNSWs search and surveys were conducted at night, with the first transect commencing within 30 min of sunset. They were then also required to implement a 25-m logging exclusion zone (approximately 0.2 ha) around any tree where a GGCS is sighted during search and survey.

However, it should be noted that SSBC requirements were only for glider records detected by FCNSW and does not extend to community or citizen science records. Further, the minimum requirements for FCNSW to conduct ‘pre-harvest’ GGCS surveys enabled FCNSW to search for GGCSs across less than 10% of the available operational logging area. The EPA also explained that the February SSBCs did not reflect the shared understanding of the EPA and FCNSW that only the first part of the search and survey had to commence within the first hour of sunset.

We initially consider survey effectiveness based on protocols instigated by the EPA up until 9 February 2024. However, we consider in discussion the implications of these additional protocols for survey success and glider conservation.

EPA Native Forestry map viewer data

Pre-logging surveys carried out by FCNSW include considerable documentation on what was done, when, and by whom. Thus, excerpts from the EPA Native Forestry map viewer show FCNSW operational maps and publicly available planning documents, the history of forestry activity and severity of the 2019/2020 Black Summer bushfires, the status and the location of the State Forest and compartment, location and immediate surroundings of the relevant compartment, assessed patch boundaries and assessed bird nest, roost or den and associated exclusion zone layers. They also show records of retained trees in the compartment and its surrounds, and colour coded attributes of retained trees (and second-tier attributes).

Maps are also provided of survey tracklogs by FCNSW staff in the compartment and its surrounds and GGSC and YBG detections, overlaid on the FCNSW Operational map for the relevant compartment or compartments (with label coloured yellow for detections 2020 or later). Further, maps which zoom in on the relevant detections show the location ID for each detection; and data tabulated to show observation date for each of the detections in the preceding maps, together with the underlying data extracted from NSW Bionet. Maps of individual assessed patches in the vicinity of glider detections recorded in the preceding maps include tracklogs by FCNSW staff in the patch and associated data relating to the patch and retained trees. This is accompanied by a table showing the date, start and end time, and distance of each tracklog by FCNSW staff carrying out the surveys.

We interrogated these data and included active compartments known to include recent detections of GGCSs or YBGSEs within 10 State forests for evaluation (Table 1). These data were downloaded from the EPA Native Forestry map viewer during April 2024 and are a subset of the data available from this map viewer. We used these data to compile a summary of the characteristics of these compartments, survey efforts by FCNSW staff, and the resultant decisions concerning protection efforts for gliders in the context of planned logging operations (Table 1) . A point-based shapefile of all assessed and retained trees in both the southern and northern CIFOA was acquired from the FCNSW Open Data Site. HBTs were extracted using SQL (where TreeType = 3 orTreeType2 = 3 or TreeType3 = 3) within ArcGIS PRO 3.0 (ESRI 2020). A raster grid with a 100-m resolution (i.e. 1 ha) was overlaid onto the point-based data and the number of points that fell within each totalled, providing a surface of HBTs per ha. Locations that had not been assessed were set to null to avoid artificial deflation of the summary statistics (mean and s.d.) extracted and included in Table 1.

CIFOA protocols and conservation of gliders in intensively logged compartments

All listed compartments within the 10 areas of State forests have records of either YBGSEs and/or GGSCs, including very recent records (Table 1). This is despite no apparent attempt to identify any species of glider during surveys (all surveys were conducted in daylight hours). These compartments also have abundant records of HBTs, as demonstrated by some retention, although usually at lower levels than designated (Table 1). Note that some or many of these designated HBTs may be relatively small or contain only very small hollows, unsuitable as den trees for these gliders.

Surveys for HBTs were conducted in each of the compartments in each of the 10 areas of State forests assessed. However, it was not possible to say from the records whether one or other of the retained (or logged) HBTs is or is not a glider den tree. It should be noted that Bionet records show some to many YBGSEs or GGSCs in (or in very close proximity to) each of these compartments (Table 1). Therefore, it is virtually certain that numerous glider den trees occur (or occurred) in each of the compartments in these 10 State forests (Table 1). Nevertheless, no den trees for either species were reported and no den tree and associated 50 m buffer was foreshadowed to be retained during and after logging of these compartments.

More recent protocols instigated by the EPA

Effort by FCNSW to survey for den trees throughout the operation of the CIFOA to February 2024 was carried out in daylight hours, preventing identification of glider den trees. While protocols instigated by the EPA on 9 February 2024 removed the need for survey, these were reintroduced soon after (16 February 2024), along with the requirement to survey within 1 h following sunset (27 May 2024). While no difference in conservation outcome could be expected by the implementation of EPA requirements introduced in early February 2024 (although retention of 14 HBTs per ha is a considerable increase in retained HBTs and in basal area over the prior rate) subsequent amendments recognised that gliders tend to leave their dens to forage within about an hour of sunset. Thus, more recent requirements to commence survey at dusk provides an improved opportunity to detect gliders and their dens.

CIFOA protocols and conservation of gliders in intensively logged compartments

The data (April 2024) suggests that no serious attempt was made to detect glider den trees in the compartments in the 10 State forests assessed to that time. Further, we have not seen any evidence of follow-up surveys used to relate glider sightings with HBTs, or evidence of spotlight (with or without playback) survey data, radio tracking data, or drone survey data in these compartments that could have provided evidence of glider den trees. Thus, surveys appeared not to be compliant with any methodology, survey protocols, or minimum survey effort requirement in relation to detecting glider dens. In other words, surveys for glider dens appear to have been ineffective, invalid, and unreliable scientifically (see Green 1979; Shrader-Frechette and McCoy 1993; Peters 1995). It is therefore reasonable to assume that by April 2024, glider den surveys were not actually carried out or not reported if they were.

Therefore, it could be concluded that the requirement in Condition 57.2 (c) of the CIFOA ‘that a broad area search be conducted that will, among other things, identify glider den trees’ was not complied with. While many HBTs were identified, FCNSW recognised the inadequacy of their survey efforts concerning locations of glider dens (see FCNSW 2023). However, recent efforts by FCNSW reported in ‘The National Tribune’ (see below) also appear inadequate.

If glider conservation is to be a consideration in forest management, then follow-up field work is required to ascertain whether these HBTs are (or are not) glider dens. It would therefore be appropriate to carry out surveys at night using spotlight protocols (see Chick et al. 2020; Cripps et al. 2021; Wardell-Johnson and Robinson 2023), radio tracking, or appropriate drone surveys (with appropriately developed protocols – see below).

Indeed, more recent work carried out by FCNSW and by Forest Alliance NSW (2024) in four of these State forests (i.e. Tallaganda, Tuggolo, Bulga, and Styx River; see Fig. 1) demonstrates an apparent inability for FCNSW to detect gliders or den trees that are readily detected by citizen scientists. Thus, community surveys (see Forest Alliance NSW 2024) detected 170 den trees, while FCNSW detected just 15 in compartments in these State forests. Further, community surveys detected 825 GGSCs, while FCNSW found 229. Thus, Forest Alliance NSW (2024) concluded that less than 1% of den trees are found by FCNSW using most recent requirements of the SSBC. Forest Alliance NSW (2024) concluded that the number of records of GGSCs is positively correlated with the number of surveys conducted, and that FCNSW apparently recognises that it is not in their interest to find GGSC or their den trees. This is because each record reduces the immediate logged area. Regardless, the failure to detect gliders or den trees when they are present has profound conservation implications.

Outcomes for gliders in intensively logged compartments not surveyed for den trees and therefore without appropriate measures to safeguard them

Recent detections of gliders (GGSC or YBGSE) in each of these compartments by parties independent of FCNSW (both to December 2023, and more recent detailed surveys) occurred despite FCNSW’s failure to detect den trees or gliders. The likely outcome of the failure to ‘conduct broad area searches that will, among other things, identify glider den trees’ is to permanently reduce these glider populations. Initially, the logging operation as planned would kill all or most of the GGSC in the compartment, either during the logging operation or soon thereafter (from predation, starvation, or exposure (see Tyndale-Biscoe and Smith 1969). The logging operation then renders the environment hostile to this species and unsuitable for other MFDS for upwards of 50 years (see Wardell-Johnson and Robinson 2023). However, by this time, most areas are scheduled to be relogged (Fig. 2a). Therefore, these environments are designated to remain permanently hostile to gliders.

Fig. 2.

Hostile environments, terminal habitat, and tomb trees in the State forests of NSW. Memorial trees in an area twice intensively logged within 60 years in (a) Nullica State Forest, (b) isolated hollow-bearing and habitat trees killed by high-intensity fire in Yambulla State Forest, (c) hostile environments for gliders (areas logged less than 50 years previously) burnt in the 2019/2020 wildfires, Nullica State Forest, and (d) tomb tree Tallaganda State Forest. All photos: Grant Wardell-Johnson.

GGSCs using den trees that have not been detected and that will be felled will most likely die directly because of the logging operation, either at the time of the operation or soon thereafter. Thus, the fate of individuals of this species following intensive logging has been well-known for over 50 years (i.e. since the pioneering work of Tyndale-Biscoe and Smith 1969). In the meantime, both the GGSC and YBGSE have shown dramatic declines in abundance associated with intensive logging carried out extensively, exacerbated by recent (2019/2020) large-scale fire events (see review by Driscoll et al. 2024).

Individual gliders using den trees that are retained as HBTs, but without the requisite buffer, are likely to be very similar to those whose den trees are removed. Thus, they are severely exposed to predators and a lack of food after the logging and burning operation. Therefore, it is likely that den trees that were not protected by a buffer of 50 m would no longer serve as den trees following the intensive logging operations. Further, recently exposed individual trees are much more prone to windthrow (see Sinton et al. 2000) or being impacted by wildfire events (e.g. Fig. 2a, b) than trees within a retained buffer (Lindenmayer and Taylor 2020). This has important implications concerning eventual recovery of stand structure.

Thus, retained HBTs (and any associated glider) without a buffer face an extreme form of edge effect (Nelson et al. 1996; Youngentob et al. 2012). These isolated retained HBTs (some of which may have been den trees) will therefore effectively serve as tomb trees (Fig. 2d) to any glider present at the time of the logging operation. While tomb trees serve as crucial components in the redevelopment of stand structure (e.g. Manning et al. 2006; Fischer et al. 2010), they also denote the loss (potentially permanently) of gliders through intensive logging in that compartment.

Unfortunately, based on operational activities elsewhere in NSW, logging return times are foreshadowed to be less than 60 years (see Wardell-Johnson and Robinson 2023). Therefore, these sites are effectively rendered permanently hostile to gliders. The evidence suggests that this constitutes serious and irreversible damage to these gliders and their environment (see Wardell-Johnson and Robinson 2023; Wardell-Johnson et al. 2024). It should be noted that many areas are now being (or have recently been) intensively logged for the second time since the commencement of woodchipping in NSW in 1968 (e.g. Fig. 2a). Initially, clearfelling without HBT retention was the usual practice (see Routley and Routley 1974). On the second rotation, isolated HBTs have been retained (despite no gliders now being present). Therefore, these HBTs serve as memorials (e.g. Fig. 2a) to populations of gliders that previously occupied the area (i.e. secondary tomb trees).

GGCS occupy home ranges of between 1.3 and 4 ha, with home ranges being larger in poorer quality habitat. Unfortunately, a 25-m logging exclusion zone (approximately 0.2 ha) around any tree where a GGSC is sighted during search and survey provides only a small area of suitable habitat within their home range, surrounded by hostile environments. This situation continues for at least 50 years (or permanently as a consequence of further logging rotations). This situation therefore condemns individual gliders to terminal habitat, as they will most likely be predated at the edges of this zone. Considering their high sensitivity to edge effect, nothing less than protection of the home range of GGCS is likely to provide opportunity for their conservation (see Environment East Gippsland Inc v VicForest (No 4) 2022 VSC668). The islands of terminal habitats for gliders formed by intensive logging are not akin to ecological (Mason et al. 2018) traps since individuals are not induced to them. Rather, they become trapped in them when the habitat around them is transformed or destroyed (as in landscape traps – Lindenmayer et al. 2011b, 2022a).

Thus, the evidence suggests that there is a real threat of serious or irreversible damage to the environment from industrial-scale logging without a prior understanding of the locations of either glider home ranges or of glider den trees. This understanding can only be achieved by effective survey (see for example Environment East Gippsland Inc v VicForest (No 4) 2022 VSC668). The methodology of this survey should be both reliable (i.e. be able to do the job asked of it) and be valid scientifically (i.e. be able to be repeated by other observers elsewhere given the same wherewithal). The approach to February 2024 was ineffective as it was apparently neither valid nor reliable. Further, survey efforts based on recently introduced protocols have apparently provided little improvement to the situation.

Alternative approaches of survey to conserving gliders

Knowing the whereabouts of individuals of species or of vital habitat features known to be impacted by logging operations is essential for wildlife conservation (Gibbons and Lindenmayer 2002; Crane et al. 2008, 2010). It is even more important where the conservation of these species at the compartment (and thus landscape and region) level is dependent on their retention during intensive logging operations (or other forms of disturbance). Given the requirement to conserve populations of threatened fauna in the context of intensive logging, one might enquire as to how this might best be done. Two approaches may be used: one that is directed towards the target animal; and the other directed towards target resources. In Victoria, the target animal approach was found to be efficacious. However, decades of research have provided ample knowledge of both the species and their requirements to allow either approach to be viable with current knowledge. Thus, in the context of resource extraction, the commitment (or otherwise) of agencies to constructively engage in surveys to enable appropriate adjustment of operational plans effectively determines the long-term sustainability of glider populations.

Compromises to enable logging and the conservation of endangered gliders

Without effective survey, strategic planning and specific management prescriptions, there is potential for native forests to no longer support MFDS such as endangered gliders at the compartment scale, and therefore to compromise conservation at the block or landscape scale (Lindenmayer et al. 2020; Smith 2020; Wardell-Johnson and Robinson 2023), thereby further reducing the function and values of forests. As a result, recent court cases (e.g. Environment East Gippsland Inc v VicForests (No 4) (2022) VSC 668) have argued that the scale and nature of the industrial-scale logging activity carried out in two Forest Management Units in the State of Victoria has led to serious and irreversible environmental damage to gliders and other MFDS. That is why retention of the home ranges of GGs, stream zones (100 m total width on all streams) and 60% basal area in logged areas were all considered necessary to provide opportunity for conservation of gliders there. This situation also applies in NSW.

Thus, it has been recognised in law in one Australian State that if MFDS are to be provided with opportunity to persist, serious strategic planning and conservation attention is required in the context of timber production. Thus, in coups foreshadowed to be logged in two Forest Management Units in Victoria, the whereabouts of high conservation values must be known (and located by the most appropriate means) so that their habitat can be protected. Further, within areas logged, a substantial reduction in the intensity of the logging operation is required.

As recognised in Victoria, it is easier to locate gliders than to locate their den trees. Thus, the targeting of species rather than their resources is more viable when the aim is to conserve populations of threatened species in the context of efficacy and reliability in survey. Regardless, where there is an apparent lack of will to achieve conservation outcomes within the agency (e.g. in Victoria, Environment East Gippsland Inc v VicForests (No 4) (2022) VSC 668), such outcomes require effective legislation and monitoring for compliance following intervention through the court process.

Thus, when ‘resource’ supply commitments lead to known (even if contested) irreversible environmental damage, there are more important considerations for conservation in the application of survey protocols than determining whether survey focus should be on the resource or the species. Regardless of a resource-led or species-led focus, it is difficult to imagine a process to ensure conservation within an organisation that places immediate resource supply ahead of sustainability (see Ludwig et al. 1993; Hilborn et al. 1995). To date, the evidence suggests that the numerous additional protocols provided by the EPA to FCNSW during 2024 have not improved outcomes for glider conservation.

Doubt concerning a commitment to conservation by FCNSW is highlighted by a recent judgement in the NSW Land and Environment Court (Cox 2024) brought by the NSW EPA. In this case, Justice Pepper fined FCNSW A$360,000 for offences related to illegally logging 53 trees in an environmentally significant forest near Eden (in the state’s south), after the 2019/2020 bushfires. Here, the court accepted an EPA submission that the agency had ‘a pattern of environmental offending, has not provided any compelling evidence of measures taken by it to prevent its reoffending, and does not accept the true extent of harm that it has caused by its offending’. Thus, Justice Pepper agreed that any penalty imposed on FCNSW ‘must serve to deter it from future criminality’. The court found an affidavit filed by FCNSW chief executive, Anshul Chaudhary, ‘constitutes no more than a bare expression of contrition and remorse’ and that FCNSW had not taken steps to remediate the harm it had caused.

Given the generality and magnitude of the impact of repeated industrial-scale logging on gliders, a case involving 53 trees near Eden, NSW is reminiscent of Inspector Clouseau and the blind beggar (Edwards 1975). Nevertheless, it does suggest a broader pattern of behaviour and seems commonplace in forestry, both nationally (e.g. Environment East Gippsland Inc v VicForest (No 4) 2022 VSC668) and internationally (e.g. Bosselmann 2010: Dancer 2021; Meriläinen and Lehtinen 2022; Nunes et al. 2024; Rohmy et al. 2024). Thus, it is necessary for oversight to be more generally mandated in the community and this oversight to be enforceable in law should conservation be considered a priority for society in the context of resource extraction. Where government agencies are responsible for oversight (even where separate or answerable to different Ministers), political capture, resource constraints, and conflicts of interest are inevitable. Thus, conflict of interest becomes a particular concern when the agencies responsible for resource extraction are also responsible for the research and monitoring of that activity, especially when not answerable to a wider body.

Scientific suppression in Government departments whereby staff are ‘rewarded or penalized on the basis of complying with opinions of senior staff regardless of evidence’ has been demonstrated (Driscoll et al. 2021). These rewards and punishments are highly consequential, defining the success or failure of individual careers subject to Government funding (Martin 1999, Driscoll et al. 2021; Zylstra and Wardell-Johnson 2024). This situation demonstrates the difficulty of enforcing conservation in an agency responsible for short-term supply commitments, even when these commitments lead to irreversible environmental harm.

Perhaps more consequential than ‘rewards and penalties’, Weberian understanding (see Bullock and Trombley 1999) suggests that people become rule-bound and uncreative in organisations and bureaucracies as they pursue narrow, specialised tasks, preventing effective oversight. Thus, extensive documentation of inconsequential activity is encouraged, driving decision making to the detriment of broader societal interest. Max Weber introduced the concept of the ‘iron cage’ to describe the increased rationalisation inherent in social life, particularly in Western capitalist societies (Baehr 2001). This ‘iron cage’ traps individuals in systems based purely on teleological efficiency, rational calculation and control at the expense of contemporary social values (Wardell-Johnson et al. 2019). Thus, Weber’s ‘polar night of icy darkness’ (Lassman 1994) becomes a rationalisation of bureaucratic processes rather than for species conservation.

Until the influence of bureaucracy and the culture of scientific suppression and Government influence on research and monitoring can be addressed, mandated requirements via third parties effectively supported in law remains the only viable oversight to enable effective conservation outcomes. Thus, even if the best possible protocols were in place, independence in the survey process itself is the most essential characteristic of the survey.