Forests Of South-western Australia Research Articles

Mechanisms by which growth and succession limit the impact of fire—A comment on Zylstra et al.'s model

Abstract Zylstra et al. (2023) hypothesise that ecological controls contribute to a decline in the potential behaviour and severity of fires burning in tall open eucalypt forests unburnt for multi‐decadal periods (>52 years). They model potential flame height in forests dominated by Eucalyptus jacksonii in southwestern Australia and argue that self‐thinning of understorey shrubs leads to a decline in suspended litter (woody necromass), which in turn leads to reduced flame heights in older fuels. Forest floor and suspended litter were not sampled as part of their field survey, and instead they describe the dynamics of these fuel components by fitting equations to data reported from previous studies. The form of equation they use to describe the accumulation of suspended litter does not account for the contributions of woody necromass other than from understorey shrubs. In particular, twig fall from the forest overstorey is likely to make an important contribution to suspended litter and is much slower to decompose than leaves and necromass from understorey shrubs. Their assumption of a decline in suspended litter is inconsistent with published research on fuel dynamics in tall open forests in southwestern Australia, which demonstrates that dead fine fuel loadings do not decline when the forest remains unburnt. In the absence of field data to support their assumption of decline in suspended litter, the broader conclusions of Zylstra et al. (2023) regarding changes in potential behaviour and severity of fires in E. jacksonii dominant forest unburnt for >52 years remain open to question. Read the free Plain Language Summary for this article on the Journal blog.

Birds pre-adapted to a road in a heterogeneous and contiguous old-growth forest: a point transect study

Roads are present globally across all habitats and their negative impacts on the landscape are being increasingly reported. Yet often more is known about the identity of roadkill than how avian assemblages are impacted by roads. This study used 100 paired point counts by the road and 400 m into the forest interior to assess if the assemblages were different and determine what species may be impacted by the road. The study was undertaken along a highway cut through one of the world’s tallest forests – old-growth karri (Eucalyptus diversicolor) forest of south-western Australia. There was no overall significant difference in species richness and abundance between road and forest interior sites, although a small number of species (4.3%) did demonstrate preferences. Overall, we suggest that the limited significant differences resulted from: (1) the narrowness of the road with the forest canopy frequently extended fully across and (2) the natural variation found in eucalypt forests, which has aided the birds as a pre-adaptation to the presence of this road – because eucalypt forests are a heterogeneous array of streams and forest heterogeneity.

Impact of braconid wasps on larval performance of longhorned borer Coptocercus rubripes Boisduval (Coleoptera: Cerambycidae) in Eucalyptus forest of southwestern Australia

AbstractIn southwestern Australia, outbreaks of cerambycids have been associated with infestation of drying and stressed trees. Felled timber provides an abundant habitat for a variety of subcortical beetles where their development can be modified by attack from natural enemies, including parasitoids. There are a variety of parasitoid wasps of cerambycids native to Australia, yet their effectiveness in controlling the larval performance of borers has been little studied. Approximately 700 Eucalyptus trees felled to realign a forest road provided an opportunity to determine how a mass of drying logs influences borer infestation rates and whether parasitoid wasps were effective in controlling borer survival. The native borer Coptocercus rubripes (Coleoptera: Cerambycidae) caused an extensive infestation of fallen trees at the clearfell site. These infestations were subsequently limited by the direct effect of parasitism from the native braconid wasps Callibracon limbatus and Syngaster lepidus emerging from a single hole in a white cocoon. The effects of parasitism showed inverse density dependency where high borer larval densities increased the chances of borer larval survival. The absence of parasitism in caged logs promoted high borer larval densities and greatly improved adult borer survival, and while this increased the demand for sapwood resources, it promoted early adult borer emergence. Control by native braconid wasps of high infestations of Co. rubripes borers attacking drying and stressed trees limits adult borer emergence and has the potential to partially regulate borer populations.

Detecting plant spatial pattern change after disperser loss: A simulation and a case study

AbstractDisruption of seed dispersal processes may affect plant population spatial structure. We used a spatial simulation model and an empirical case study to assess the conditions under which the loss of seed dispersers has a detectable effect on a species' spatial pattern. Our simulation experiments suggested that detecting spatial change following disperser loss will be difficult, except when rates of fruit removal are initially high and then completely disappear. To contextualize the simulation modeling, we used spatial point pattern analyses to characterize the spatial pattern of two large‐seeded species (Leucopogon nutans, a fire‐killed seeder shrub and Macrozamia riedlei, a long‐lived, resprouting cycad) in the jarrah (Eucalyptus marginata) forests of southwestern Australia. The plant species' primary disperser, the emu (Dromaius novaehollandiae), was absent from one of the sites we considered, but present at the other two. There was no detectable difference for either plant species in the strength of aggregation between sites with and without emu. However, even if disperser loss may not greatly affect local spatial structure for most plant species, it is likely to be important for long distance dispersal and genetic structuring of populations, so accurate characterization of the dispersal kernel is critical, especially in terms of plant emigration.

Habitat features act as unidirectional and dynamic filters to bat use of production landscapes

Conserving global biodiversity requires careful management of production landscapes, especially in this era of rapid environmental change. The habitat filtering framework has been used for predicting species responses to land-use changes. Habitat filters are essentially features that may slow, or limit, species use of certain habitats. We wanted to determine if this framework could identify habitat and landscape filters that predicted bat use of restored forest at the species-specific and trait group levels. We surveyed bat activity, vegetation structure, and landscape characteristics at 64 sites over two years in restored northern jarrah (Eucalyptus marginata) forests of south-western Australia. Filters to use of restored forest were present for all bats, other than the open space group. We detected dynamic filters to use of restored forest by the open space edge group and unidirectional filters for the closed space edge and closed space groups. Filters to bat use of restored forests were species-specific and related to habitat, rather than landscape, features. In landscapes with relatively low patch-matrix contrast, such as the northern jarrah forest, management actions to reduce filters should focus on habitat features. To manage for the persistence of specific species within restored forest patches, tree density and midstory cover should aim to be at, or close to, reference forest levels.

Does population distribution matter? Influence of a patchy versus continuous distribution on genetic patterns in a wind‐pollinated shrub

AbstractAimUniform spatial population distributions are predicted to result in lower among‐population genetic differentiation and higher within‐population genetic diversity than naturally patchy distributions, but there have been surprisingly few attempts to isolate this effect from confounding factors. We studied the widespread wind‐pollinated shrub Allocasuarina humilis that is common in a geologically stable landscape characterized by long‐term population persistence to test the influence of semi‐continuous versus patchy population distributions on genetic patterns. We also investigated whether A. humilis shows the high population connectedness and genetic diversity typically associated with wind pollination, a relatively uncommon and little‐studied syndrome in this landscape.LocationHeath‐shrublands (‘heath’) and forests of south‐western Australia.MethodsPopulations were sampled from heath and forest regions, which respectively exhibited semi‐continuous and patchy population distributions. Genetic structure and diversity were assessed for 27 populations using eight nuclear microsatellite markers and three chloroplast regions. Phylogeographical history was examined using Bayesian phylogeny reconstruction, parsimony analysis and tests of expansion.ResultsHigh haplotype diversity is consistent with long‐term population persistence across most of the species’ range. Nuclear markers showed low overall population differentiation and no geographical structure over c. 900 km, reflecting extensive pollen dispersal. For both marker types, patchily distributed forest populations were substantially more differentiated with significantly lower within‐population diversity than semi‐continuous heath populations. Phylogeographical analysis revealed evidence for earlier colonization of heath than forest and recent expansion into wetter forests, consistent with progressive long‐term climatic drying.Main conclusionsHigh population connectedness and genetic diversity probably resulted from wind pollination in combination with dioecy and long life span. Patchy population distributions appear to have influenced genetic structure and diversity through lower pollen and seed dispersal, lower effective population sizes and greater genetic drift. Our approach illustrates the value of minimizing confounding variables by testing the effect of a variable ecological trait within a single species.

The responses of a critically endangered mycophagous marsupial (Bettongia penicillata) to timber harvesting in a native eucalypt forest

Mycophagous bioturbators provide ecosystem services that can be important for the resilience and restoration of ecosystems. Among the Australian mammals, mycophagy is most prevalent within the Potoroidae (bettongs and potoroos). However, proportionally more species of Potoroidae are either recently extinct or currently threatened than any other mammalian family in Australia, and they are among the least studied. The critically endangered woylie, or brush-tailed bettong (Bettongia penicillata), is a mycophagous, ground dwelling ‘ecosystem engineer’ that was one of Australia’s most abundant and widely distributed potoroids prior to European settlement. After substantial range contraction, however, the remaining indigenous populations are now restricted to eucalypt forests in south-western Australia. Using an experimental approach, we investigated the population responses of the woylie to timber harvesting in these forests. Nine treatments, including varying logging intensities and unharvested controls, were applied at 22 sites. The abundance of the woylie in the harvested areas, in unharvested stands between logged areas, and in extensive unharvested stands outside the harvest management area were compared using a replicated before-after-control-impact (BACI) repeated measures design and capture-mark-recapture modelling. A total of 5860 captures of 815 individuals were recorded during 35 trapping sessions over 16years (one year preceding, two years during, and 13years after disturbance). Capture rate was a good index of abundance for this species and woylie abundance, survivorship and recruitment were not adversely affected by silvicultural practices in the jarrah (Eucalyptus marginata) forest. On the contrary, the harvested areas may have afforded some localised protection when an unrelated, species-wide decline began three years after harvesting disturbance ended; woylie numbers declined by up to 77% and 95% in harvested and unharvested areas, respectively. Thus the nature and spatial extent of the timber harvesting regimes investigated in this study were not a major threatening process for this species. However, ongoing monitoring and evaluation are necessary to ensure that timber harvesting activities remain benign in the face of a changing climate, possible increased mortality from introduced predators, disease, and further declines in the abundance of this critically endangered marsupial.

Successional changes in feeding activity by threatened cockatoos in revegetated mine sites

Context Provision of key habitat resources is essential for effectively managing species that have specific ecological requirements and occur in production landscapes. Threatened black cockatoos in the jarrah (Eucalyptus marginata) forest of Western Australia have a wide range, so their conservation requires support from all land tenures, not just reserves. Mining in the jarrah forest temporarily removes cockatoo feeding habitat, so it is important to understand how cockatoos exploit revegetated areas for food resources. Aims We aimed to determine whether there were successional patterns in cockatoo feeding activity in revegetation aged from 4 to 23 years at three mine sites in the jarrah forest in south-western Australia. Methods We surveyed 232 plots in revegetation to document (1) structural and floristic variation in vegetation across mine sites and revegetation ages, (2) differences in cockatoo feeding activity across mine sites and revegetation ages on the basis of feeding residues and (3) any edge effect reflecting preferential use of vegetation at the interior or exterior of mine pits. We also documented the frequency of occurrence of cockatoo food plants and feeding residues in 480 plots in unmined forest to compare with revegetated areas. Key results Marri (Corymbia calophylla) and jarrah were commonly consumed in unmined forest and Banksia and Hakea species were also fed on to a lesser extent. Revegetated mine pits provided food within 4 years and continued to do so up until the oldest plots studied (23 years). The relative importance of food plants shifted from proteaceous species in young revegetation to myrtaceous species in intermediate to older revegetation. However, extent of feeding on myrtaceous species in older revegetation did not equate to feeding rates in unmined forest, with lower frequencies recorded in revegetation. Conclusions Black cockatoos fed in revegetation at all three mine sites, despite variations in vegetation age, structure and floristics. Feeding on proteaceous and myrtaceous food plants occurred within 4 and 7 years of revegetation being established, respectively, indicating that some food resources are restored quickly after mining disturbance of the jarrah forest. Implications Our results emphasise the importance of monitoring fauna recolonisation over appropriate time scales, to understand how successional processes in revegetation influence fauna population persistence in production landscapes.

Recovery of Tall Open Eucalypt Forest in South-Western Australia following Complete Crown Scorch

AbstractWe investigated the response of overstorey and mid-storey trees in tall open forest of Eucalyptus diversicolor F. Muell., Eucalyptus jacksonii Maiden, and Corymbia calophylla (Lindl.) K.D. Hill & L.A.S. Johnson over an eight-year period following complete crown scorch by high intensity fire in March 2001. More than 90% of E. diversicolor and E. jacksonii and 85% of C. calophylla remained alive four years after fire, having replaced their crowns by re-sprouting from epicormic buds on the stems and larger branches. Mid-storey trees were more severely affected by fire with almost one third of Allocasuarina decussata (Benth.) L.A.S. Johnson stems and all above-ground stems of Agonis flexuosa (Willd.) Sweet killed back to ground level. Abundant seedling regeneration of E. diversicolor and E. jacksonii developed in the year following the fire but seedling density and stocking declined progressively over subsequent years. Survival of E. diversicolor seedlings was higher than for E. jacksonii seedlings, consistent with findings of earlier research. For both species, initial seedling densities were significantly greater within 25 m of potential seed trees, but seedling density was otherwise unrelated to the basal area of surrounding forest. Eight years after the fire, 38% of sample quadrats (4 m2) were stocked with one or more eucalypt saplings, with saplings of E. diversicolor and E. jacksonii having a mean height of 5 m. Saplings established following the 2001 fire could add a further age class to the stand provided that this cohort persists during subsequent fires. The results of our study provide further evidence to support the view that tall open eucalypt forests in south-west Western Australia rarely experience complete stand replacement even following intense fires, and that multi-aged stands are common.

Fire‐stimulated reproduction in the resprouting, non‐serotinous conifer Podocarpus drouynianus (Podocarpaceae): the impact of a changing fire regime

AbstractSpecies with fire stimulated reproduction (fsr) are common in Mediterranean climate ecosystems. We investigated how season of, and time since, fire affects seed production in Podocarpus drouynianus F. Muell., a dioecious resprouting coniferous shrub endemic to the jarrah (Eucalyptus marginata Sm.) forests of southwestern Australia, and if the now largely managed fire regime in these forests poses a risk to its persistence. We hypothesised that, like other species showing fsr, seed production in P. drouynianus would be limited to the first few years following fire and seed set would be lower after spring burns. Mature plants regenerated rapidly from buried stem tissue (lignotuber) after fire, producing abundant sporophylls in autumn 12–18 months later. Stands burnt in autumn showed peak seed production 1 year later, while for those burned in spring, peak seed production was delayed until the second autumn after fire. Limited seed production occurred for up to 3 years following fire, but no seed production was observed in longer unburnt (>10 years since fire) stands. While we did not observe a significant impact of fire season on seed production, seed weight and viability were lower for spring‐burnt plants. Population‐level effects associated with plant density may also have negative impacts on P. drouynianus demography, with females within a small population burnt in autumn producing very few seeds 12 months following fire. Interactions between climate change, fire regimes and fire management practices need to be considered in order to best safeguard the long‐term persistence of this conifer species.

Study of seed dispersal by Emu (Dromaius novaehollandiae) in the Jarrah (Eucalyptus marginata) forests of south-western Australia through satellite telemetry

Global positioning system (GPS) technology for tracking wildlife continues to evolve at a remarkable pace. As animal movement is increasingly recognised as being critical for several ecological processes, advanced telemetry technology permits collection of a high volume of data across short time intervals that was previously unobtainable. Here we describe the use of GPS telemetry to track the movements of five tagged Emus (Dromaius novaehollandiae Latham) released within the Jarrah (Eucalyptus marginata Sm.) forests of south-western Australia. The Emu plays a significant role as a seed disperser for many species. Describing the movement patterns of this species is a key requirement in refining the extent and significance of its contribution to seed dispersal, both locally and over long distances. We found that Emus followed a typical correlated random walk pattern and that each bird demonstrated a variable response to the landscape in terms of behaviour, extent of movement and habitat selection. From a methodological perspective, 50% of our devices detached before 30 days of GPS locations could be collected, reflecting a need for device refinement for future studies on large ratites. Nevertheless, our preliminary data provide useful insights into the movements of the Emu and potential impacts on seed dispersal within the Jarrah forests.

Regeneration failure threatens persistence of Persoonia elliptica (Proteaceae) in Western Australian jarrah forests

The severe disruption of herbivore relationships can result in catastrophic, demographic consequences for plant populations. We investigated the potential roles of herbivory, fire and their interaction, in the observed long-term regeneration failure of Persoonia elliptica R.Br. (Proteaceae), an understory tree species of fire-prone jarrah (Eucalyptus marginata Sm.) forests in southwestern Australia. Seed production, storage and viability were assessed, as was seedling recruitment in both the presence and absence of fire (a potential germination cue), using experimental herbivore exclosure plots. We also sought to determine the ‘herbivory zone’ (height) within which P. elliptica was susceptible to browsing. Herbivores, primarily the western grey kangaroo, preferentially consumed leaves of P. elliptica up to a browsing height of 1.5 m. Viability of fresh seeds was low at ca. 39 % and rapid viability loss was observed in the soil seed bank, with only ca. 5 % of seeds remaining viable for >1 year. Germination was restricted almost solely to burned areas and survival of recruits to the confines of herbivore exclosures. We suggest that an increase in the primary herbivore, combined with low viable seed supply, is the likely cause of continuing regeneration failure in this species. The slow growth of the species suggests that without intervention, seedlings and juvenile plants will be unable to escape the herbivory zone. Management actions to facilitate recruitment might best focus on the combination of managed fires to break seed dormancy, followed by fencing to protect seedlings from large herbivores.

Sudden forest canopy collapse corresponding with extreme drought and heat in a mediterranean-type eucalypt forest in southwestern Australia

Drought and heat-induced forest dieback and mortality are emerging global concerns. Although Mediterranean-type forest (MTF) ecosystems are considered to be resilient to drought and other disturbances, we observed a sudden and unprecedented forest collapse in a MTF in Western Australia corresponding with record dry and heat conditions in 2010/2011. An aerial survey and subsequent field investigation were undertaken to examine: the incidence and severity of canopy dieback and stem mortality, associations between canopy health and stand-related factors as well as tree species response. Canopy mortality was found to be concentrated in distinct patches, representing 1.5 % of the aerial sample (1,350 ha). Within these patches, 74 % of all measured stems (>1 cm DBHOB) had dying or recently killed crowns, leading to 26 % stem mortality six months following the collapse. Patches of canopy collapse were more densely stocked with the dominant species, Eucalyptus marginata, and lacked the prominent midstorey species Banksia grandis, compared to the surrounding forest. A differential response to the disturbance was observed among co-occurring tree species, which suggests contrasting strategies for coping with extreme water stress. These results suggest that MTFs, once thought to be resilient to climate change, are susceptible to sudden and severe forest collapse when key thresholds have been reached.

Ecology of black cockatoos at a mine-site in the eastern jarrah-marri forest, western Australia.

Three threatened black cockatoos inhabit the Jarrah Eucalyptus marginata-Marri Corymbia calophylla forest of southwestern Australia: Baudin’s Cockatoo Calyptorhynchus baudinii, Carnaby’s Cockatoo C. latirostris, and Forest Redtailed Black Cockatoo C. banksii naso [FRTBC]. Their local ecology in relation to anthropogenic disturbance is poorly known, hampering effective conservation management. Therefore we studied their group size, site occupancy patterns, habitat use, and food plants at a mine-site and its surrounds in the eastern forest over three years. FRTBC showed similar group sizes and occupancy across seasons, suggesting year-round residency and no marked seasonality in movements and grouping patterns. In contrast, Carnaby’s Cockatoos were up to twice as abundant in spring and summer, indicating migrating or transient flocks and some year-round residents. Few Baudin’s Cockatoos were present in summer, but their abundance increased at other times. All three cockatoos were observed in modified or humanmade habitats such as mine-site rehabilitation, farm paddocks, and pine plantations. Carnaby’s Cockatoos used the broadest habitat range. We documented feeding on 16 plant species, with Carnaby’s Cockatoos eating at least 10. Examination of feeding residues as well as observations of behaviour were essential to obtain a complete picture of feeding. Current mine-site rehabilitation protocols provide food for all three black cockatoos within a decade and should continue to do so long-term if Marri is maintained in the seed mix. However, because climate change scenarios predict declining rainfall over much of southwestern Australia, the plant species used to revegetate mine-sites and other landscapes may need to be reconsidered. For areas that do not specify restoring a jarrah forest landscape, the selective use of exotic or non-endemic flora better adapted to lower rainfall conditions may be an option.

Disconnection of groundwater from surface water causes a fundamental change in hydrology in a forested catchment in south-western Australia

In south-western Australia, significant declines in annual rainfall in recent decades have been accompanied by even greater declines in annual streamflow. The disproportionate decline in annual streamflow is perplexing and while there has been speculation about the causes, the mechanisms responsible for the disproportionate decline have not been demonstrated. This study seeks to clarify the role of groundwater in the disproportionate decline in annual streamflow in a small catchment in the jarrah forest by examining records of annual streamflow, stream salinity and groundwater which progressively declined from 1976 to 2011. The records span the transition from connected groundwater–surface water systems to disconnected. This provided a unique opportunity to differentiate the groundwater contribution to streamflow for two reasons. Firstly, because the change in streamflow following disconnection can be largely attributed to streamflow that was previously generated because groundwater was connected. Secondly, because groundwater was the main source of stream salinity and hence stream salinity was a natural tracer which indicated the presence and relative proportion of groundwater in streamflow. Disconnection occurred around 2001 and was signalled by a change in the annual stream salinity signature from moderately high and variable, to low and constant, and by the transition in piezometric levels at the catchment outlet from mostly above ground, to mostly below ground. Following disconnection, the average runoff coefficient which had been slowly declining, abruptly fell by more than half and subsequently remained relatively low and constant. This indicated that whilst groundwater was connected it played a key role in streamflow generation. The contribution by groundwater to streamflow generation was non-linear and was dominant at higher rainfalls. The annual stream salinity signature indicated that direct groundwater discharge to the stream was a relatively minor component, especially at higher rainfalls. Hence connected groundwater contributed to streamflow generation mostly indirectly, thus amplifying other streamflow-generating processes, by facilitating additional surface runoff and/or throughflow which were relatively fresh. As groundwater levels, and hence connectivity, declined, the amplifying effect of groundwater-facilitated streamflow generation also declined. We suggest that the large disparity between the rates of decline in annual rainfall and inflow into reservoirs elsewhere in the forests in south-western Australia mostly reflects the aggregate loss of connectivity in the catchments of streams contributing inflow into the reservoirs.

Overstorey and juvenile response to thinning and drought in a jarrah (Eucalyptus marginata Donn ex Sm.) forest of southwestern Australia

Aims: Forest thinning is expected to affect tree water use and carbon assimilation, but the related influence from climate variability is little known. Recent forest thinning in the Wungong catchment coincided with a record dry year following the thinning, which provides a rare opportunity to understand the climate influence on the thinning effect. Methods: A field experiment was conducted to examine changes before and after thinning, especially the rainfall, soil moisture, leaf water status, tissue isotope signature (13 C and 15 N) and N concentration of overstorey and understorey juvenile trees of Eucalyptus marginata (Donn ex Sm.). Results: Despite the post-thinning drought, surface soil was moister and juvenile jarrah plants were less water stressed, attributable to reduced rain interception and transpiration as a result of less canopy cover. The overstorey was under stress but mainly due to drought rather than by thinning. The concentration of N declined in both tree stems and juvenile leaves along with available N in soil, suggesting a soil N limitation. No treatment effects were detected from leaf relative water content and tissue isotope signature (13 C and 15 N). Conclusions: The drought effects were superimposed over the thinning effects on overstorey growth, with stemwood δ13C being a major indicator of water stress. The water relations and carbon assimilation of understorey juveniles were however dependent more on topsoil moisture, and the wetter soil during the year following thinning enhanced growth activity and hence the depletion of 13 C (more negative δ13C) in juvenile leaves.

Hydraulic traits and water use of Eucalyptus on restored versus natural sites in a seasonally dry forest in southwestern Australia

Eucalyptus is a globally important genus for reforestation but eucalypt growth in non-native environments has uncertain ecohydrological consequences. This study investigated the hydraulic structure and function of juvenile (2.5–10m height) Eucalyptus marginata on restored mine sites and forest sites in a seasonally dry climate in southwestern Australia. We measured sap flow, leaf area, sapwood area, leaf water potential, stomatal conductance and weather variables and applied a simple model of plant water use to examine hydraulic traits across chronosequences of trees (using height as an index of age) in each environment. Younger trees on restored sites grew three times faster and used four times more water per unit leaf area (0.53kgm−2day−1) than forest trees, consistent with greater light, water and nutrient availability on restored sites. To maintain hydraulic homeostasis, trees on restored sites reduced leaf area/sapwood area ratio by 25%, increased sapwood permeability by 20%, and reduced stomatal conductance and transpiration by 50% to counterbalance fourfold increases in height and leaf area. In contrast, forest trees reduced leaf area/sapwood area ratio by 33% but increased sapwood permeability by 100% and stomatal conductance and transpiration by 50% in response to increased water availability, in addition to increased height and leaf area. A linear relationship between leaf area and water use for forest trees was indicative of hydrological equilibrium, whereas a curvilinear relationship for trees on restored sites suggested transition from high to lower water availability. Young eucalypts are likely to develop traits that are hydraulically compatible with their climate and substrate, but they may also adjust their architecture and physiology over time in response to changes in water availability. Trees in reforested landscapes with modified soils and initially abundant soil moisture may develop hydraulic architectures that are more efficient than found in native forests, which may pose risks if they can only access a fixed volume of soil. The long-term sustainability of such systems is likely to depend on trees eventually developing appropriate hydraulic architectures to cope with regimes of water availability more akin to native forests, especially in drought-prone environments.

An exploratory study of community expectations regarding public forests in Western Australia

Summary For much of the 20th century the management of public forests in Western Australia focused on timber production and economic outputs. Shifts in environmental attitudes over the last four decades have contributed to a much broader set of community expectations. This paper analysed these expectations regarding public forests in south-western Australia at the start of the 21st century. A two-stage survey approach included a face-to-face interview followed by a questionnaire. The questionnaire consisted of a comprehensive list of 176 items that forests potentially provide, such as conservation, scenery, bushwalking and timber products, and respondents were asked to indicate the extent of their support for each. Those surveyed covered a range of ages and affiliations including academia, conservation, forestry, primary production, Indigenous interests and young people. Clearly evident was strong support for the aesthetic values of these forests and their natural environment, with weaker but still notable support for using forest resources. The comprehensive list of items in the questionnaire provides a novel, rapid means of assessing community expectations, with potential benefits for forestry planning and policy development.

First report of Phoma clematidina the cause of leaf spot-wilt disease of Clematis pubescens in Australia

Leaf lesions and wilt of Clematis pubescens were observed in the Jarrah (Eucalyptus marginata) forest of South-Western Australia in 2009. A Phoma sp. was consistently isolated from the infected tissues and its morphological characteristics were determined. The identity of the fungus was confirmed by sequencing of the internal transcribed spacer (ITS) region of the rDNA operon and Phoma clematidina was identified. A pathogenicity test was conducted and Koch’s postulates were fulfilled by re-isolation of the identified fungus. This is the first report of P. clematidina causing leaf lesions and wilt of Clematis pubescens in Australia.

Home Range Size and Micro‐habitat Density Requirements of Egernia napoleonis: Implications for Restored Jarrah Forest of South Western Australia

Compared to natural forests, coarse woody debris (CWD) is typically scarce in restored forests due to the long time it takes to develop naturally. In post‐mining restored forests in the Jarrah forest of south western Australia, CWD is returned at densities of one log pile per hectare. We tested the adequacy of these densities for meeting the micro‐habitat requirements of Napoleon's skink (Egernia napoleonis), a species rarely found within restored sites. Home range size and overlap, and micro‐habitat densities used by skinks, were measured by radio‐tracking 12 individuals in natural, unmined forest. Napoleon's skinks had small home ranges (0.08 ± 0.02 ha), based on 8 individuals with sufficient fixes. All skinks overlapped in home ranges, with average overlaps of 43.5 ± 8.6%. Ten of the 12 skinks shared micro‐habitats and 4 shared them simultaneously, which indicates some social tolerance. This will influence as to how many micro‐habitats are required. Micro‐habitats were used at high densities: logs at 49.2 ± 8.8 ha−1 and woody debris piles at 12.4 ± 4.8 ha−1. Based on these densities, it is recommended that CWD is returned to restored forests at densities of 60 ha−1, which should provide sufficient micro‐habitats for multiple skinks. Due to the infeasibility of returning such CWD densities across large areas of restored forest, CWD could be preferentially returned as patches, large enough for numerous home ranges, adjacent to unmined forest, or as corridors between unmined forest. These recommendations for returning micro‐habitats should be tested for effectiveness in encouraging recolonization of restored forest by Napoleon's skink and other species.