Jarrah Research Articles

‘Ecological forestry’ and eucalypt forests managed for wood production in south-western Australia

The model of ‘ecological forestry’ has evolved as a part of the development of the concept of ecosystem management. ‘Ecological forestry’ emphasises that manipulation of a forest ecosystem should consider, and as far as practicable work within the limits of, natural disturbance patterns prior to extensive human alteration of the landscape. This paper evaluates the extent to which forest management practices in jarrah ( Eucalyptus marginata) and karri ( Eucalyptus diversicolor) forests of south-western Australia align with this view of the characteristics and appropriate silviculture of ‘ecological forestry’. Characteristics and appropriate silviculture of ‘ecological forestry’ are evaluated in relation to (i) the stand level decisions of stand structure and harvest timing and (ii) the landscape level decisions of harvest levels and age structures, and spatial patterns of harvest. Forest management in south-western Australia is found to align with appropriate silviculture under this model of ‘ecological forestry’. Additionally, the landscape triad of areas managed to ‘ecological forestry’ principles, conservation reserves and areas managed to production forestry is in place in the south-western forests of Australia. Strengths and weaknesses in the model of ‘ecological forestry’ and the ability to interpret consistency of practices in the forests of south-western Australia with the characteristics of ‘ecological forestry’ are identified.

In planta selfing and oospore production of Phytophthora cinnamomi in the presence of Acacia pulchella

This paper provides the first evidence of A2 type 1 and type 2 isolates of Phytophthora cinnamomi producing selfed oospores in planta in an Australian soil and in a potting mix. Oospores were observed in infected lupin ( Lupinus angustifolius) roots incubated for 7 d either in the substrate under potted Acacia pulchella plants, or in soils collected from under and near varieties of A. pulchella in jarrah ( Eucalyptus marginata) forest. The A2 type isolates varied in their ability to produce selfed oospores and none were produced by A1 isolates. The gametangial association was amphigynous and spores were predominantly spherical with diameters from 13–40 μm. The oospores were viable but dormant. Two A2 type isolates produced small numbers of selfed oospores with amphigynous antheridia axenically in Ribeiro's liquid medium within 30 d, and one A2 type 2 isolate produced oospores after mating with an A1 strain. Evidence is presented that the presence of roots of Acacia pulchella, and particularly A. pulchella var. glaberrima and var. goadbyi, enhances the production of oospores.

A new homothallicPhytophthorafrom the jarrah forest in Western Australia

A homothallic Phytophthora, isolated at irregular intervals since the 1980s from Western Australian jarrah (Eucalyptus marginata) forest sites, has been previously misidentified as P. citricola based on morphological characters. Based on rDNA sequencing, it has been shown to be an undescribed species that is provisionally designated ‘Phytophthora sp. WA2’ pending a full description. It has been associated with lower stem lesions and root necrosis on dying 1- to 2-year-old jarrah seedlings growing in rehabilitated open-cut bauxite mine pits.

Phytophthora inundatafrom native vegetation in Western Australia

Phytophthora inundata was found associated with a dead Xanthorrhoea preissii in Eucalyptus marginata (jarrah) forest in the south-west of Western Australia in January 2005. The isolate was sterile in pure culture and when paired with tester isolates of A1 and A2 mating types of other Phytophthora species. Mature sporangia were produced in 4 hours and discharged zoospores very soon after maturation. Some hyphal swellings were observed. Another isolate of P. inundata was isolated in 2005 from soil from Dandaragan on the sandplains north of Perth. Phytophthora isolates collected from dying native vegetation near the South Coast in 1986 and near Mount Barker in 1997 were also shown to be P. inundata. This is the first record of P. inundata from Australian natural ecosystems.

A stem injection of phosphite protectsBanksiaspecies andEucalyptus marginatafromPhytophthora cinnamomifor at least four years

Longevity of effectiveness of stem-injected phosphite against Phytophthora cinnamomi was determined in two ways. Injected and not injected Banksia grandis and Eucalyptus marginata were challenge inoculated with P. cinnamomi at different times over an 8-year period. The mortality of injected and not injected B. attenuata and B. grandis was monitored over a 16-year period on active disease fronts. Duration of phosphite effectiveness was determined from the time after stem injection to 50% inhibition of either lesion length or girdling following challenge inoculation with P. cinnamomi and time to 50% mortality following injection of trees in disease fronts. For both B. grandis and E. marginata, time to 50% inhibition of lesion length increased from 4–5 years for 50 g phosphite/L to at least 10 years for 200 g phosphite/L. Time to 50% inhibition of girdling was significantly less than that for lesion length. In B. grandis, time to 50% inhibition of girdling increased with phosphite concentration from 2.9 years for 50 g phosphite/L to 10 years for 200 g phosphite/L. Time to 50% inhibition of girdling in E. marginata was 4 years. Predicted response surfaces of the effect of phosphite concentration and time on inhibition of lesion length and girdling showed that there was a much more gradual decline in predicted inhibition in E. marginata than the more susceptible B. grandis. An injection of 100 g phosphite/L of Banksia trees on disease fronts delayed time to 50% mortality by 3 to 4.8 years (mean 4.1±0.6 years). At least 4 years of effectiveness of phosphite against P. cinnamomi in native communities is much greater than the ≲2 years found in agriculture. The effects of phosphate competition and adaptation to infertile environments on longevity of effectiveness of phosphite are discussed. Demonstration that the effectiveness of an injection of phosphite against P. cinnamomi will last at least 4 years in native flora confirms the practical utility of using phosphite injection for the control of P. cinnamomi in threatened communities. A greater understanding than available at present of the differences in phosphite uptake, within-plant distribution, loss and effectiveness between targeted plant species can optimise current phosphite prescriptions. Additional keywords: apparent mortality rate, host defence mechanisms, longevity, persistence, phosphonate, phytotoxicity.

The ecology of the rufous treecreeper in the jarrah forest of south-western Australia and implications for its conservation and management

Rufous treecreepers (Climacteris rufa) are common in southern jarrah forests of Western Australia, but nothing has been recorded of their ecology in the region. I investigated the foraging and nesting ecology of the species in the southern jarrah forests from January 1994 to April 1996. Rufous treecreepers foraged exclusively on two eucalypt species, jarrah and marri, and foraged on trees that were significantly larger and taller than random. Foraging on the ground, logs and fallen trees was relatively infrequent. Nest hollows were also located exclusively in jarrah and marri trees that were significantly larger and taller than random. The important foraging and nesting resources for the species in the southern jarrah forest appear to be large mature and overmature eucalypts. Anthropogenic impacts in the region, primarily logging, should aim to retain these resources in affected areas to improve the survival prospects of the species. When compared with studies in wandoo woodlands, the results of the present study indicate that the conservation of ground-layer habitat is likely to be of less importance in the jarrah forest. These habitat differences indicate that site-specific information is critical if the management and conservation of individual species is to be effective.

Application of phosphite in a high-volume foliar spray delays and reduces the rate of mortality of fourBanksiaspecies infected withPhytophthora cinnamomi

There were two experiments in which three phosphite concentrations were sprayed onto the foliage of either Banksia brownii, B. baxteri or B. coccinea naturally infected with Phytophthora cinnamomi in the Esperance Plains bioregion of Western Australia, or B. grandis artificially infected with P. cinnamomi in Eucalyptus marginata forest of south-western Australia. Plots were either sprayed with one of three concentrations of phosphite (2.5, 5 or 10 g phosphite/L) and penetrant-spreading agent or sprayed only with penetrant-spreading agent. Mortality of the Banksia species, understorey and crown health, plant height and soil inoculum at each site were the dependent variables. There were no significant differences in overstorey phytotoxic necrosis rating of B. brownii, B. baxteri and B. coccinea between phosphite treatments 2.7 and 4 years after the first spray. The greatest phytotoxic effect of phosphite application was the stunting of B. coccinea growth, which did not occur in B. brownii, B. baxteri and B. grandis. For naturally infested Banksia species, greatest mortality occurred in B. brownii and least in B. coccinea, with B. baxteri being intermediate between mortality for B. brownii and B. coccinea. There was a significant reduction in apparent mortality rate and increase in years to 50% mortality following foliar application of phosphite to the four Banksia species. Greatest reduction in mortality of the Banksia species occurred for concentrations between 5–10 g phosphite/L. Challenge inoculation showed that spray treatments of 5 g and 10 g of phosphite/L were effective in B. grandis, 2.2 years after spray. The proportion of positive P. cinnamomi soil samples from the top 3 cm of soil was significantly greater than the proportion positive from 30 cm below the soil surface in infested B. brownii and B. coccinea, but there was no significant difference in the proportion of positive P. cinnamomi soil samples between depth of sampling for B. baxteri. Phosphite had no significant effect on the frequency of isolation of P. cinnamomi from the soil of infested B. baxteri and B. coccinea. Determination of phosphite effectiveness against P. cinnamomi and phytotoxic responses between plant species will assist prescription optimisation for the most effective protection of threatened flora.

Comparison of colonisation byPhytophthora cinnamomiin detached stem tissue ofEucalyptus marginatain relation to site disease status

Eucalyptus marginata is the dominant tree of a forest community in south-western Australia. It is susceptible to infection by Phytophthora cinnamomi and is usually rare on long-infested sites. Ex situ stem inoculation was used to compare the susceptibility of E. marginata plants in long-infested sites and adjoining uninfested sites. Plants were found to be less susceptible on some long-infested sites but other factors may also be important in regulating regeneration and survival of E. marginata.

Hemispherical digital photographs offer advantages over conventional methods for quantifying pathogen-mediated changes caused by infestation ofPhytophthora cinnamomi

Estimates of canopy closure using hemispherical digital images, canopy cover using a point-intercept method, ground cover, number of plant species and total plant species cover were used to quantify the impact of Phytophthora cinnamomi in disease centres in Banksia shrubland, Banksia woodland and Eucalyptus marginata forest biomes of the South-West Botanical Province of Western Australia. Estimates of the time required to capture and analyse data and correlations were used to contrast the five methods. For canopy closure or cover, hemispherical digital images were on average, seven times faster to capture and analyse than the point-intercept method. For both canopy closure and ground cover, mean values from three point samples were not significantly different to mean values from transects across the disease front. Differences in canopy closure and ground cover between biomes and disease obtained from point sampling showed the same trends as transects. Canopy closure differed significantly between biome, being greatest for E. marginata forest, least for Banksia shrubland and intermediate for Banksia woodland. Ground cover was greatest for Banksia shrubland, least for E. marginata forest and intermediate for Banksia woodland. For all biomes there was significantly less canopy closure in diseased than adjoining healthy areas. There was no significant difference in ground cover between diseased and adjoining healthy areas of Banksia shrubland, but significantly less ground cover in diseased than adjoining healthy areas in the Banksia woodland and E. marginata forest. Canopy closure and ground cover are likely measuring different aspects of the impact of P. cinnamomi and, therefore, both should be measured when determining pathogen-mediated changes. Advantages of using hemispherical digital images over the other methods for determining temporal and spatial changes associated with P. cinnamomi infestation are discussed.

Field survival and growth of clonal, micropropagated Eucalyptus marginata selected for resistance to Phytophthora cinnamomi

Clones of jarrah ( Eucalyptus marginata), micropropagated from glasshouse-grown seedlings selected for resistance or susceptibility to Phytophthora cinnamomi, were planted in a former bauxite mine-site in the jarrah forest and inoculated with P. cinnamomi. Mortality after 13 years in resistant clones was 0–30%, while that of susceptible clones was 40–100%. Mean heights of resistant clones after 13 years were 7.8–13.6 m, while heights of surviving susceptible clones were 0.9–6.7 m. The resistance character of the seedling ortets was transmitted consistently to the clones. The field mortality of clones of some rare, apparently resistant seedlings selected from susceptible half-sib families was low after 1 year, but approached that of the susceptible clones after 2 years. The results show that Phytophthora-resistant jarrah ortets can be selected using stem-inoculation of glasshouse-grown seedlings; the resistance of the resulting clones has been validated in the field in an inoculation trial.

The effect of nitrogen source and concentration, medium pH and buffering on in vitro shoot growth and rooting in Eucalyptus marginata

This work examined the effect of nitrogen source and medium buffering on the micropropagation of Eucalyptus marginata Donn ex Sm. The number of shoots was increased when media contained 2-(N-morpholino) ethanesulfonic acid (MES) but this increase was minor and only applied to one of the two clones tested. Highest root production was obtained when the medium contained 7.5 mM nitrogen in a ratio of 2NO3−:1NH4+ and was buffered with 10 mM MES. In the rooting medium the pH was influenced most significantly by the nitrogen source, and then whether the medium was buffered. The media pH remained relatively constant when nitrate was the sole nitrogen source and this was assisted by the addition of 10 mM MES. Lower concentrations (<10 mM) of MES were less effective in buffering media over a four-week culture period in both shoot multiplication and rooting medium.

Gene flow of the canker pathogen Botryosphaeria australis between Eucalyptus globulus plantations and native eucalypt forests in Western Australia

Abstract The eucalypt plantation industry in Western Australia provides a unique opportunity to study the movement of pathogens between closely related host taxa. Eucalyptus globulus, a native to Tasmania and south‐eastern Australia, is the predominant species in Western Australian plantations, often being planted adjacent to native forest containing Eucalyptus marginata and Eucalyptus diversicolor. Since the commencement of the plantation industry 20 years ago, several fungal species, previously known only to eastern Australia or overseas, have been reported on E. globulus in Western Australia. Botryosphaeria australis is a newly described species, recently found causing cankers on Acacia spp. in eastern Australia. However, during a routine survey, B. australis was found to be the predominant species associated with E. globulus plantations and native Eucalyptus spp. in Western Australia. In this study, six short simple repeat markers were used to evaluate genetic diversity and gene flow between collections of B. australis from native eucalypt forest and E. globulus plantations at two locations in south‐western Australia. In both cases, there was no restriction to gene flow between the plantations and the adjacent native forest. Botryosphaeria australis has now been isolated from a wide range of hosts across south‐western Australia and was not isolated from E. globulus in Tasmania or South Australia. This extensive distribution and host range suggests B. australis is native to Western Australia. This study demonstrates the ability of a pathogen to move between plantation and forests.

Trunk invertebrate faunas of Western Australian forests and woodlands: Seeking causes of patterns along a west‐east gradient

Abstract Trunk‐associated invertebrates were sampled on marri trees (Eucalyptus (Corymbia) calophylla) along a transect from Karragullen, near Perth, through to Dryandra, 150 km to the south‐east. This represents a drop in annual rainfall from 1078 to 504 mm, which is accompanied by a change from jarrah (Eucalyptus marginata) forest to wandoo (Eucalyptus wandoo) woodland. Invertebrates were sampled by intercept traps, which collect invertebrates that attempt to land on the trunks, and bark traps, which collect invertebrates that move, or live, on the trunk. Trends are reported here at the ordinal level. The variety and abundance of invertebrates sampled was generally greater in the intercept than the bark traps. Invertebrate abundance, activity and biomass on bark were strongly seasonal, with greater numbers being found during the moister periods. Invertebrate abundances tended to be greater at the drier, eastern end of the transect, particularly on the three sites within wandoo woodland. These trends were analysed in terms of rainfall, soil nutrients and plant community composition. The analysis failed to detect an underlying influence of any of these factors, suggesting that the observed trends on marri trunks may be the result of invertebrate responses to the dominant tree species at the western and eastern ends of the transect, namely jarrah and wandoo respectively.

Effective concentration of phosphite in controlling Phytophthora cinnamomi following stem injection of Banksia species and Eucalyptus marginata

SummaryThe effect of phosphite concentration on lesion development by Phytophthora cinnamomi in stems and roots of Banksia grandis and Eucalyptus marginata and in stems of Banksia coccinea was assessed during a 4.3 year period after stem injection of phosphite. Lesion length 6 weeks after inoculation was significantly less in roots of B. grandis trees that had been stem injected with three concentrations of phosphite (50, 100 and 200 g phosphite/l) at two rates (1 and 2 ml/cm of stem circumference) compared with the not‐injected control. With the exception of B. grandis trees injected with 50 g phosphite/l, lesion length for the high rate was not significantly different to the low rate. In roots of E. marginata, lesion development in response to phosphite was different to that in roots of B. grandis; lesion length in roots did not differ significantly between phosphite concentration and rate. Lesion length and girdling in stems of B. grandis and E. marginata was significantly less in those injected with phosphite than in not injected stems. One year after injection, callus tissue had contained lesions in stems injected with phosphite. By 4.3 years after injection of both hosts there was a steep significant negative linear relationship between phosphite concentration and either lesion length or girdling, with greatest lesion development in not injected stems and least in stems injected with 100 g phosphite/l. Recovery of P. cinnamomi from lesion margins 1 year after injection, was significantly less in trees injected with phosphite than in not injected trees. The amount of plant death reflected containment of lesion extension and girdling, and reduction of recovery of P. cinnamomi with phosphite concentration; 4.3 year after injection there was a steep significant negative linear relationship between phosphite concentration and percentage of plant death. In contrast to B. grandis and E. marginata, there was a U‐shaped non‐linear relationship between phosphite concentration and effectiveness of phosphite in controlling lesion extension and girdling in B. coccinea. Containment of lesion extension and girdling with time was greatest for B. coccinea stems injected with 25 g phosphite/l, least for stems not injected, and intermediate in stems injected with 50 and 100 g phosphite/l. As in B. grandis and E. marginata, containment of lesion extension and girdling in B. coccinea with phosphite concentration was reflected in the amount of plant death. The non‐linear response to phosphite of some plant species indicated that injected concentration for B. coccinea should not exceed 50 g phosphite/l, whereas injected concentrations of up to 100 g phosphite/l could be recommended for B. grandis. Longevity of action of phosphite for 4–5 years in native plant species after one injection makes phosphite injection a practical control option for the control of P. cinnamomi disease front extension and the protection of threatened flora. Research into the effect of factors affecting longevity of action of phosphite would facilitate optimization of timing of injection.

State‐and‐Transition Successional Model for Bauxite Mining Rehabilitation in the Jarrah Forest of Western Australia

Abstract Alcoa World Alumina Australia has been rehabilitating bauxite mines in the jarrah (Eucalyptus marginata) forest of western Australia for more than 35 years. Completion criteria were developed in the 1990s for native species rehabilitation, with various desirable characteristics described as the rehabilitation ages. Successional models can be useful in mining rehabilitation for predicting whether sites are developing along the desired trajectory toward the rehabilitation objective. The current rehabilitation objective is to establish a self‐sustaining jarrah forest ecosystem, planned to enhance or maintain water, timber, recreation, and conservation values. The major objective of this study was to present a state‐and‐transition successional model that assists Alcoa to identify sites that will and will not meet identified completion criteria. Agreed completion criteria and vegetation data collected from native species rehabilitation from 9 months to 15 years old were used to construct a state‐and‐transition model. The model identified the various desired and deviated successional states and factors that cause transitions between these states. Five desirable and nine deviated states were identified and described in detail. Key indicators relating to desired and deviated states include eucalypt density, species richness, legume density, topsoil cover, vegetation structure, ripping depth, and tree health and form. Identified management manipulations to return deviated states to the desired successional trajectory include ripping, reseeding, replanting, weed control, and tree thinning. Some of the identified thresholds between desired and deviated states will require significant management input (e.g., reripping), whereas others require little or no input (e.g., recovery following wildfire). Of the 6,429 ha of native species rehabilitation undertaken between 1991 and 2002, 98% is on or above the desired successional trajectory. More than half of the rehabilitated area is regarded as being above the desired trajectory because of high tree density. Although these sites meet the existing completion criteria, management input may be required in the future, emphasizing the importance of identifying maximum and minimum completion criteria. The state‐and‐transition model of successional development is a practical but rigorous land management tool that has the potential to be applied in a wide variety of ecosystems and wide range of land uses.

Optimising smoke treatments for jarrah (Eucalyptus marginata) forest rehabilitation

Alcoa is undertaking rehabilitation in the jarrah (Eucalyptus marginata D.Don ex Sm.) forest of Western Australia, following bauxite mining. One of the methods used in the rehabilitation program is broadcasting seeds; however, about two-thirds of species require seed-dormancy-breaking treatments. Smoke overcomes dormancy and enhances the germination of many jarrah forest species. Smoke-application methods were investigated to find the best seed treatment for 64 jarrah forest species. The optimum duration of seed imbibition in aqueous smoke and dilution of the aqueous smoke product were also investigated. The method of smoke application was important. Smoke water enhanced the germination of 12% of species, whereas aerosol smoke enhanced the germination of 6% of species. Both Grevillea pilulifera (Lindl.) Druce and Velleia trinervis Labill. had germination enhanced by both smoke-application methods. Aerosol smoke inhibited the germination of Clematis pubescens Endl. and Hypocalymma angustifolium (Endl.) Schauer. A total of 78% of species did not exhibit significantly enhanced germination when smoke treated, including the two species inhibited by smoke treatment. Germination was equivalent following 1- and 12-h imbibition in the aqueous smoke extract. Dilutions of the aqueous extract Regen 2000 Smokemaster from 1 to 3% were optimal for the germination of Marianthus bicolor (Putt.) F.Muell and Stylidium amoenum R.Br., even after subsequent washing with water, demonstrating the irreversible nature of smoke treatments. For species that did not exhibit smoke-enhanced germination, other dormancy-breaking treatments may be required before a response to smoke is elicited. These results have application to a wide variety of natural managed lands, disturbed and designed landscapes.

In vitro pollen viability and pollen storage in Eucalyptus marginata (Myrtaceae)

Summary This study examines pollen germination in Eucalyptus marginata. In vitro pollen germination is best with a medium containing calcium and boron, such as the Brewbaker and Kwack medium (300 ppm hydrated calcium nitrate, 200 ppm hydrated magnesium sulphate, 100 ppm potassium nitrate and 150 ppm boric acid with 25% maltose). High levels of genotypic variability in pollen (10–60% viability) make it desirable to test the pollen quality of individual trees before use. Pollen of E. marginata has characteristics common to many other eucalypt species, but its adaptations to a relatively dry environment can be seen in its ability to germinate without prior desiccation, unlike pollen from cool temperate eucalypts. Daily changes in weather conditions have little effect on in vitro pollen germination in E. marginata. Pollen of E. marginata may be stored successfully at –20°C or -80°C for at least one year.

Congruence between phylogeographic patterns in cpDNA variation in Eucalyptus marginata (Myrtaceae) and geomorphology of the Darling Plateau, south-west of Western Australia

Phylogeographic patterns in the cp genome of Eucalyptus marginata Don ex Sm., a species common in the mesic region of south-western Australia, were investigated by using RFLP analysis. The chloroplast diversity was structured into two geographically distinct lineages and nested clade analysis inferred historical fragmentation as the major influence on the phylogeographic pattern. The lineages were separated along the geomorphological boundary of the Darling Scarp, which separates the Coastal Plain from the Darling Plateau. The divergence between the lineages is consistent with uplifting of the Darling Plateau in the late Neogene. Further geographic structuring in haplotype distributions was evident in the forest lineage on the Darling Plateau, where one sublineage was present in the central forest region and another was restricted to the south-eastern region. The level of divergence between these sublineages was similar to that between divergent lineages that have been identified in comparative phylogeographic studies of cpDNA variation in three species widespread throughout south-western Australia. In these species, divergence was attributed to the influence of significant changes in climatic oscillations across the semi-arid region during the mid-Pleistocene. The divergence identified in this study indicates that the influence of climatic change was widespread throughout south-western Australia, including the mesic, higher-rainfall region.

The abundance of a threatened arboreal marsupial in relation to anthropogenic disturbances at local and landscape scales in Mediterranean-type forests in south-western Australia

This study investigated associations between the relative abundance of the threatened ngwayir (western ringtail possum, Pseudocheirus occidentalis) and anthropogenic disturbances at local and landscape scales within the publicly-managed jarrah ( Eucalyptus marginata) forests of south-western Australia. Logging, fire, fox ( Vulpes vulpes) control and forest fragmentation were investigated in relation to the relative abundance of ngwayir at 90 sites within an area of 285,000 ha east of Manjimup; the location of the last remaining substantial population of ngwayir in jarrah forest. Overall, ngwayir abundance was greatest in areas with limited anthropogenic disturbance. At the local-scale, ngwayir abundance was negatively associated with greater fire intensity. At the landscape-scale, it was positively associated with fox control and negatively associated with forest fragmentation and distance from non-remnant vegetation (i.e., agriculture and tree plantations). Abundance was also greatest in predominantly unlogged landscapes and in forests that had been regrowing for an average of 40 years since the landscape was most recently logged, in other words, where logging was historically least intense. Interactions between fox control efforts and forest fragmentation were also important. This study emphasises the importance of conducting research at appropriate spatial scales and to account for the synergistic effects of the causes of decline. An adaptive management approach to the mitigation of the agents of decline is recommended. Indirect evidence indicates that high value habitat for ngwayir has in all likelihood been selectively cleared for agriculture, owing to its fertile and productive nature. Habitat loss is, therefore, also likely to be a major cause of the modern decline of the species. While many jarrah forest areas that support remaining high abundances of the ngwayir have been incorporated into reserves, conservation of ngwayir habitat and populations outside reserves also will be essential for the recovery and long-term viability of the species.

Do Eucalyptus plantations host an insect community similar to remnant Eucalyptus forest?

Abstract We examined the potential of forest plantations to support communities of forest‐using insects when planted into an area with greatly reduced native forest cover. We surveyed the insect fauna of Eucalyptus globulus (Myrtaceae) plantations and native Eucalyptus marginata dominated remnant woodland in south‐western Australia, comparing edge to interior habitats, and plantations surrounded by a pastoral matrix to plantations adjacent to native remnants. We also surveyed insects in open pasture. Analyses focused on three major insect orders: Coleoptera, Lepidoptera and Hymenoptera. Plantations were found to support many forest‐using insect species, but the fauna had an overall composition that was distinct from the remnant forest. The pasture fauna had more in common with plantations than forest remnants. Insect communities of plantations were different from native forest both because fewer insect species were present, and because they had a few more abundant insect species. Some of the dominant species in plantations were known forestry pests. One pest species (Gonipterus scutellatus) was also very abundant in remnant forest, although it was only recently first recorded in Western Australia. It may be that plantation forestry provided an ecological bridge that facilitated invasion of the native forest by this nonendemic pest species. Plantation communities had more leaf‐feeding moths and beetles than remnant forests. Plantations also had fewer ants, bees, evanioid wasps and predatory canopy beetles than remnants, but predatory beetles were more common in the understory of plantations than remnants. Use of broad spectrum insecticides in plantations might limit the ability of these natural enemies to regulate herbivore populations. There were only weak indications of differences in composition of the fauna at habitat edges and no consistent differences between the fauna of plantations adjacent to remnant vegetation and those surrounded by agriculture, suggesting that there is little scope for managing biodiversity outcomes by choosing different edge to interior ratios or by locating plantations near or far from remnants.