Jarrah Forest Of South-western Australia Research Articles

Soil Characteristics and Fertility of the Unique Jarrah Forest of Southwestern Australia, with Particular Consideration of Plant Nutrition and Land Rehabilitation

The jarrah forest is a natural ecosystem with significant endemism in the flora and fauna. The forest stands on the western edge of the ancient Great Plateau of Western Australia on the granitic shield of the Yilgarn craton (2.5 Gya). The long-term migration of soluble iron and aluminium led to the formation of bauxite ore. The regolith ore is bound by surficial topsoil and deep pallid zone kaolinite clays, primarily used in land rehabilitation. We investigated the chemical fertility of the substrates, along with key physical properties. We found the capacity of these soils to provide a stable growth medium differed considerably in their ability to retain and supply nutrients. These substrates are deficient in nitrogen, phosphorus, and micronutrients. In the topsoil, 15% of total P is plant-available, while in the pallid zone layer, only 1% of total P is available. 31P-NMR showed no organic P in the pallid zone, whereas the topsoil had significant organic P and, consequently, a supply of phosphate ions. This shows the importance of organic P in the topsoil for ecosystem nutrition when inorganic fertilisers are not applied in state-of-the-art restoration schemes.

Temporal longevity of unidirectional and dynamic filters to faunal recolonization in post‐mining forest restoration

AbstractUnderstanding the factors, or filters, that preclude the recolonization of, and population persistence in, restoration areas by fauna is important for maximizing the biodiversity benefits of restoration. We investigated filters through a long‐term study examining reptile and mammal recolonization of, and population persistence in, post‐mining restoration in the northern jarrah forest of southwestern Australia. Neither mammal community composition, nor individual mammal species, differed between unmined forest and restoration but reptile communities did and some reptile species were significantly less abundant in restoration than in unmined forest. We concluded that there were no filters to mammal recolonization and persistence but that there were both unidirectional (decreasing gradually over time) and dynamic (fluctuating over time) filters to reptile recolonization of post‐mining restoration that influenced both recolonization and population persistence of some reptile species. Low volumes of coarse woody debris appeared to be a unidirectional filter that will slow recolonization by some reptile species for decades or even centuries. Canopy cover appeared to be a dynamic filter that fluctuated over a period of >7 years and precluded population persistence of some reptile species that had already recolonized the post‐mining restoration. A dearth of studies made it difficult to generalize how widespread these filters were in restoration areas but studies of thinning and burning in natural forests suggested they were likely to be widespread. Although management techniques to reduce the effect of unidirectional and dynamic filters remain poorly developed, their development and adoption will improve the ability of restoration to facilitate fauna recolonization and persistence and better contribute towards biodiversity conservation.

A standardised Landsat time series (1973–2016) of forest leaf area index using pseudoinvariant features and spectral vegetation index isolines and a catchment hydrology application

Remotely-sensed imagery from Landsat dating back to 1972 is now available from the United States Geological Survey free-of-charge as a level 1 terrain corrected product. However, to take full advantage of the time series requires that the earlier multispectral scanner (MSS) imagery be integrated with the later thematic mapper (TM), enhanced thematic mapper (ETM+) and operational land imager (OLI) imagery. Here we describe a simple, generic approach to processing Landsat scenes to develop a standardised time series of leaf area index, a key biophysical attribute of forests, for a study region in the northern jarrah forest of south-western Australia. The five-step approach utilised the main features in near infra-red (NIR)-red space of a dark point, soil line and a radiating set of ratio index isolines. Firstly, digital numbers were converted to top of atmosphere reflectance. Secondly, the red and NIR bands of all scenes were atmospheric corrected using long-established deep water supply reservoirs within the study region as invariant ‘dark objects’. Thirdly, adjustment of the NIR band such that the soil line was consistently located on the 1:1 line in NIR-red space across scenes both from the same sensor and from different sensors, taking advantage of a >40 year record of bauxite mining operations to identify pseudo-invariant bare-ground targets. Fourthly, an inter-sensor calibration of spectral vegetation indices (SVIs) to ensure that SVI isolines from different sensors were consistent. Finally, application of a relationship between SVIs and an extensive multi-year dataset of ground-based LAI measurements to generate a time-series of leaf area index (LAI). We demonstrate a simple application of the LAI time-series by investigating the relationship between rainfall, forest LAI as affected by different land use activities, and streamflow in the study region in the south west of Australia. The time-series could be used to improve prediction and modeling of hydrological changes in the region resulting from changes in catchment forest cover.

Conserving reptiles within a multiple-use landscape: determining habitat affiliations of reptile communities in the northern jarrah forest of south-western Australia

Disturbed landscapes can provide habitat for a variety of species; however, for fauna, a strong understanding of their habitat affiliations is critical both to detect species and to develop management prescriptions to maintain their populations. We assessed habitat affiliations of common, uncommon and rare reptile species in a multiple-use landscape, the northern jarrah forest of south-western Australia. To identify predictors of reptile occurrence, we related reptile presence/absence, or relative abundance, to habitat, climatic and seasonal variables. Because the reptiles studied have cryptic behaviours and low numbers of detections, we used a combination of analyses including non-metric multi-dimensional scaling, occupancy and regression models. We identified specific habitat affiliations for the most common species and potential linkages with vegetation structure for most uncommon species. There were insufficient detections to determine habitat affiliations accurately for most rare species. Often species were detected too infrequently to determine specific habitat variables that influence occupancy and detection, and altering survey time and scale may increase detections so that habitat affiliations can be determined. However, in highly speciose landscapes, like our study area, we may not be able to wait until we have enough detections to define the habitat affiliations of all reptiles before we make management decisions. Therefore management activities that maintain habitat heterogeneity and complexity is likely to be the best strategy to conserve the most reptile species.

Outbreak of Phoracantha semipunctata in Response to Severe Drought in a Mediterranean Eucalyptus Forest

Extreme climatic events, including droughts and heatwaves, can trigger outbreaks of woodboring beetles by compromising host defenses and creating habitat conducive for beetle development. As the frequency, intensity, and duration of droughts are likely to increase in the future, beetle outbreaks are expected to become more common. The combination of drought and beetle outbreaks has the potential to alter ecosystem structure, composition, and function. Our aim was to investigate a potential outbreak of the native Eucalyptus longhorned borer, Phoracantha semipunctata (P. semipunctata), following one of the most severe droughts on record in the Northern Jarrah Forest of Southwestern Australia. Beetle damage and tissue moisture were examined in trees ranging from healthy to recently killed. Additionally, beetle population levels were examined in adjacent forest areas exhibiting severe and minimal canopy dieback. Severely drought-affected forest was associated with an unprecedented outbreak of P. semipunctata, with densities 80 times higher than those observed in surrounding healthier forest. Trees recently killed by drought had significantly lower tissue moisture and higher feeding damage and infestation levels than those trees considered healthy or in the process of dying. These results confirm the outbreak potential of P. semipunctata in its native Mediterranean-climate Eucalyptus forest under severe water stress, and indicate that continued drying will increase the likelihood of outbreaks.

Early Differential Responses of Co-dominant Canopy Species to Sudden and Severe Drought in a Mediterranean-climate Type Forest

Globally, drought and heat-induced forest disturbance is garnering increasing concern. Species from Mediterranean forests have resistance and resilience mechanisms to cope with drought and differences in these ecological strategies will profoundly influence vegetation composition in response to drought. Our aim was to contrast the early response of two co-occurring forest species, Eucalyptus marginata and Corymbia calophylla, in the Northern Jarrah Forest of southwestern Australia, following a sudden and severe drought event. Forest plots were monitored for health and response, three and 16 months following the drought. Eucalyptus marginata was more susceptible to partial and complete crown dieback compared to C. calophylla, three months after the drought. However, resprouting among trees exhibiting complete crown dieback was similar between species. Overall, E. marginata trees were more likely to die from the impacts of drought, assessed at 16 months. These short-term differential responses to drought may lead to compositional shifts with increases in frequency of drought events in the future.

Feeding activity of threatened black cockatoos in mine-site rehabilitation in the jarrah forest of south-western Australia

Land clearing threatens three black cockatoo species (forest red-tailed black cockatoo, (Calyptorhynchus banksii naso), Carnaby’s cockatoo (Calyptorhynchus latirostris), and Baudin’s cockatoo (Calyptorhynchus baudinii) endemic to south-western Australia, so revegetation is important to their recovery. Over three years we studied cockatoo activity in 7–14-year-old mine-site rehabilitation in the region’s jarrah (Eucalyptus marginata)–marri (Corymbia calophylla) forest to give the most detailed description to date of the use of rehabilitation by the birds. Pits varied floristically and structurally (despite similar rehabilitation prescriptions), but interior and exterior plots (100 m2) were similar within pits. Using feeding traces (e.g. chewed husks), and behavioural observations we confirmed feeding within eight years of revegetation. Plots containing feeding trace were similar to plots without, so factors determining black cockatoo feeding may not be apparent at small scales. Returning food resources reflected vegetation succession, with regenerating marri and fast-maturing proteaceous species providing most food. Carnaby’s cockatoo ate Banksia and Hakea seeds and Baudin’s cockatoo and the forest red-tailed black cockatoo consumed marri seeds. Banksia squarrosa, Hakea undulata, H. prostrata and marri were common foods in all years. Revegetation efforts elsewhere should consider these species, within the constraints of rehabilitation protocols addressing multiple aims.

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.

English

Over the last 20 years, mining companies throughout Australia have increasingly adopted an objective of establishing sustainable native ecosystems following mining. A significant area of risk associated with mine closure is the question of completion criteria for native ecosystem rehabilitation - what standards will regulators and the community accept as part of an overall mine closure plan, which if met, will result in lease relinquishment? Two examples from mines located in forest and woodland habitat in different parts of Australia illustrate how companies have adopted an innovative approach to the development of ecological completion criteria. Alcoa World Alumina Australia mines bauxite in the jarrah forest of south-western Australia. Shallow mining (~4 m) occurs in isolated pods averaging 10 ha in size. The overall objective of rehabilitation is 'to restore a self-sustaining jarrah forest ecosystem, planned to enhance or maintain water, timber, recreation and conservation values'. Completion criteria were developed after extensive liaison with stakeholders. The criteria are assessed at five different stages, ranging from planning (prior to mining) to late (10-15 years). More than 25 years of research data enabled Alcoa to set criteria that include a range of biodiversity and ecosystem function measures. Wesfarmers Curragh Mine in central Queensland is located in a woodland environment. The open-cut coal mine produces large spoil areas that are reshaped and planted to an open woodland/grassland community. A recent study recommended completion criteria which state (in part) that 'The objective of rehabilitation following mining at Curragh is to establish a stable, self-sustaining native ecosystem that fulfils designated land uses including protection of water resources and nature conservation, and which.is similar in composition and function to that occurring in representative unmined reference sites'. Compared to those of Alcoa, the Curragh criteria reflect differences in the pre-mining environment, climate, and the mining operation. This paper describes the similar approach used to develop completion criteria at the two mines, and illustrates how the issue is being addressed in Australia.

The life history of Trichosurus vulpecula hypoleucus (Phalangeridae) in the jarrah forest of south-western Australia

The common brushtail possum (Trichosurus vulpecula) is noted for its morphological, biological and ecological variability across its range. Despite having suffered substantial population declines since European settlement, relatively little has been published on the south-western Australian subspecies, the koomal (T. v. hypoleucus). This study reports morphological, reproductive and general life-history data from an 18-month study of a population in the southern jarrah (Eucalyptus marginata) forest at Chariup (part of Perup), near Manjimup, in south-western Australia. As one of the smallest subspecies, adult males of T. v. hypoleucus averaged 1616 g and females averaged 1470 g. Sexual dimorphism also occurred with head length and pes length, but not tail length. A single autumn breeding season occurred in both 2002 and 2003, in which all adult females bred and produced a single young between February and May. The onset of autumn births was associated with the end of the summer drought. Unlike many other Trichosurus populations, no spring breeding pulse or ‘double-breeding’ events were observed. At least 83% of pouch young survived to pouch emergence. The growth rate of offspring was initially linear, but became curvilinear and approached an asymptote after ~5 months. Most females bred for the first time when they were 1 year old. On the basis of testis size, males also matured at 1 year old. The body condition of adult males, but not adult females, changed significantly over time and followed an apparently seasonal pattern in which their condition was poorest in winter and best in summer. While many of the life-history traits of the Chariup population were similar to those of other south-western Australian populations of T. v. hypoleucus, the most striking variations included age at maturity, extent of spring breeding pulse and female fecundity. Further comparisons with conspecifics elsewhere in Australia and New Zealand also highlight the variability exhibited by T. vulpecula across its range. Some aspects of the biology of T. v. hypoleucus were particularly similar to those observed for T. v. arnhemensis in northern Australia.

The life history of Pseudocheirus occidentalis (Pseudocheiridae) in the jarrah forest of south-western Australia

Life-history attributes are described for the threatened ngwayir or western ringtail possum (Pseudocheirus occidentalis) in inland jarrah (Eucalyptus marginata) forest east of Manjimup, south-western Australia. Data on 81 individuals were collected over 18 months. There was no sexual dimorphism and body size was similar to that found in other P. occidentalis populations, but larger than the closely related P. peregrinus in eastern Australia. Breeding at Chariup was more strongly seasonal than that of coastal populations, with 77% of births in May–June and the remainder in October–November. All neonates were singletons except for one instance of non-viable twins. No females bred twice in the same year. The growth rate of the head length of pouch young (<5 months of age) was 0.245–0.362 mm day–1 and curvilinear toward an asymptote thereafter. Temporal variations in body condition, coat condition and ectoparasites were significant. Mortality was highly seasonal (84% of deaths were April–September) and predominantly caused by predation, mainly by fox (Vulpes vulpes) and cat (Felis catus). More effective and strategic control of introduced predators prior to and during autumn/winter, could therefore improve the viability of jarrah forest populations. Nutrition appears to influence many of the life-history traits of P. occidentalis. Nutrition also may partly explain the differences in size, life history and conservation status between P. occidentalis and P. peregrinus.

Grazing by Kangaroos Limits the Establishment of the Grass Trees Xanthorrhoea gracilis and X. preissii in Restored Bauxite Mines in Eucalypt Forest of Southwestern Australia

Abstract This study examined factors affecting germination, survival, and growth of the grass trees Xanthorrhoea gracilis and X. preissii on newly rehabilitated bauxite mine pits in the jarrah forest of southwestern Australia. Grazing by kangaroos (Macropus fuliginosus) was the major factor in reducing survival and growth of both species during the first 2 years. Provision of artificial grazing protection increased survival and growth (plant mass) of both species by 3‐fold. Grazing by native vertebrates has not previously been identified as affecting mine restoration in Western Australia. Initial germination rates from sown seeds of X. preissii at eight replicate sites ranged from 25 to 64% with a mean of 42%. Corresponding figures for X. gracilis were 5–42% with a mean of 17%. Germination of X. gracilis was greater on heavier, moister soils, but X. preissii germinated better on sandier soils. High levels of initial germination did not ensure high survival. Plants of both species grew bigger and survived better on the lighter, sandy soils. Xanthorrhoea seedlings located in the depressions created by the ripping process grew larger than seedlings on the slopes of the riplines. The presence of plants of other species did not have a significant effect on survival. However, these plants facilitated the growth of both species when artificial grazing protection was unavailable. Plants of other species reduced the growth rates of Xanthorrhoea seedlings where artificial grazing protection was provided. Artificial shade by itself had no significant effect on growth of either species. In rehabilitated bauxite mines in the jarrah forest, the provision of grazing protection is recommended to ensure successful establishment and early survival of Xanthorrhoea spp.

Long‐Term Trends in Faunal Recolonization After Bauxite Mining in the Jarrah Forest of Southwestern Australia

Abstract Fauna serve a key role in many forest ecological processes. Despite this, few studies have considered long‐term faunal recolonization after mining and rehabilitation of forest ecosystems. In the jarrah forest of southwestern Australia, permanent fauna monitoring sites have been established in bauxite mined areas rehabilitated in 1990 and in a range of representative unmined forest control sites. At each site mammals, birds, reptiles, and ants were surveyed in 1992, 1995, and 1998. The aims of the monitoring were to develop a better understanding of faunal recolonization trends, to produce recommendations for promoting fauna return, and to consider which techniques and fauna groups are best suited for monitoring recolonization. The results showed that successional trends varied between fauna groups. Generalist foraging mammals recolonized rapidly, whereas small predators took longer. Feral mice were initially abundant and then declined. Birds gradually recolonized, and after 8 years bird communities were very similar to those in unmined forest sites. Reptile species took longer, and after 8 years numbers of species remained lower than in unmined forests. Species richness and diversity of ants in 8‐year‐old rehabilitation were comparable with those of unmined forest in some rehabilitated sites but were lower in others. The composition of ant communities was still different from that of unmined sites. Ant species that only use disturbed forest declined rapidly in abundance as rehabilitation aged. The results suggest that although the rates of faunal recolonization will vary, with time most or all mammal, bird, reptile, and ant species should inhabit rehabilitated bauxite mines. The densities of many are likely to be similar to those in unmined forest, but for others it is too early to know whether this will be the case. Techniques for promoting fauna return are discussed. This study demonstrates that no single fauna group is suitable for use as an overall “indicator” of faunal recolonization; different fauna species and groups reflect different aspects of faunal succession.

Long-term trends in avifaunal recolonisation of rehabilitated bauxite mines in the jarrah forest of south-western Australia

Alcoa of Australia Limited rehabilitates areas in the jarrah forest of south-western Australia following bauxite mining. One of the aims of the company's rehabilitation programme is to re-establish the faunal communities which existed prior to mining. In the summers of 1981, 1987 and 1993, company biologists conducted bird surveys as part of a case study to determine the extent of avifaunal recolonisation in representative mined areas. Analysis of monitoring data collected during the three surveys of the same areas showed considerable variation in the avifaunal communities of three rehabilitated sites. Numbers of bird species and bird diversity in a site seeded with dense understorey continued to increase, and by 1993 all avifaunal community parameters measured in this site were equal to or greater than those recorded in healthy unmined forest. Bird species numbers increased in a site given fresh topsoil but not seeded between 1981 and 1987; however, all parameters showed little further change by 1993. The oldest site, which was not seeded or given fresh topsoil, showed the greatest degree of change. In 1981, it supported only one bird species, but by 1993 all bird community parameters were similar to those recorded in the site which received fresh topsoil but no seed. Species composition of all rehabilitated sites' avifauna also changed. The similarity of bird community composition increased over time. By 1993, the healthy forest communities were more similar to those of some rehabilitated sites than to those of forest degraded by dieback disease. The study demonstrated that development of the vegetation community is a key factor controlling the composition of bird communities in rehabilitated mine sites. Recommendations are given to further promote avifaunal recolonisation following mining.

Diet and foraging behaviour of brush-tailed phascogales (Phascogale tapoatafa) in the jarrah forest of south-western Australia

The diet and foraging behaviour of an arboreal marsupial, the brush-tailed phascogale (Phascogale tapoatafa tapoatafa), was examined in the jarrah forest of south-western Australia. Radio-tracking was used to confirm the species’ nocturnal foraging habit and to make direct observations of foraging behaviour. Eleven stomachs, and a collection of 45 scats obtained during summer and autumn, were microscopically examined for content. The availability of major prey items (invertebrates found on or under the bark of tree trunks) was quantified. Phascogales proved to be foraging generalists, and their diet predominantly consisted of invertebrates. Some invertebrate taxa appeared to be preferred but few taxa were avoided. Active pursuit of vertebrates was negligible. However, the species appears opportunistic, and scavenging of vertebrates may contribute to the diet. Nectar was also taken, appearing to be a particularly prized but rare and patchy food source. It is suggested that the current and former distributions of this species have been constrained by both the seasonal reliability of rainfall and the diversity of food resources.

Factors affecting the abundance of hollows in logs in jarrah forest of south-western Australia

Examination of 1272 fallen logs at ten 1-ha sites in the Western Australian jarrah ( Eucalyptus marginata) forest located 206 hollows suitable for use by ground-dwelling mammals. Poisson regression analysis identified several factors positively associated with the number of hollows in logs: larger logs, logs bearing evidence of low to moderate fire damage, logs in intermediate stages of decomposition and logs that had been subject to termite attack typically had the greatest number of hollows. Of these factors, fire has the greatest potential as a tool for managing the resource of hollows in the jarrah forest.

Water yield issues in the jarrah forest of south-western Australia

The jarrah forest of south-western Australia produces little streamflow from moderate rainfall. Water yield from water supply catchments for Perth, Western Australia, are low, averaging 71 mm (7% of annual rainfall). The low water yields are attributed to the large soil water storage available for continuous use by the forest vegetation. A number of water yield studies in south-western Australia have examined the impact on water yield of land use practices including clearing for agricultural development, forest harvesting and regeneration, forest thinning and bauxite mining. A permanent reduction in forest cover by clearing for agriculture led to permanent increases of water yield of approximately 28% of annual rainfall in a high rainfall catchment. Thinning of a high rainfall catchment led to an increase in water yield of 20% of annual rainfall. However, it is not clear for how long the increased water yield will persist. Forest harvesting and regeneration have led to water yield increases of 16% of annual rainfall. The subsequent recovery of vegetation cover has led to water yields returning to pre-disturbance levels after an estimated 12–15 years. Bauxite mining of a high rainfall catchment led to a water yield increase of 8% of annual rainfall, followed by a return to pre-disturbance water yield after 12 years. The magnitude of specific streamflow generation mechanisms in small catchments subject to forest disturbance vary considerably, typically in a number of distinct stages. The presence of a permanent groundwater discharge area was shown to be instrumental in determining the magnitude of the streamflow response after forest disturbance. The long-term prognosis for water yield from areas subject to forest thinning, harvesting and regeneration, and bauxite mining are uncertain, owing to the complex interrelationship between vegetation cover, tree height and age, and catchment evapotranspiration. Management of the forest for water yield needs to acknowledge this complexity and evaluate forest management strategies both at the large catchment scale and at long time-scales. The extensive network of small catchment experiments, regional studies, process studies and catchment modelling at both the small and large scale, which are carried out in the jarrah forest, are all considered as integral components of the research to develop these management strategies to optimise water yield from the jarrah forest, without forfeiting other forest values.

Early regrowth in rehabilitated bauxite minesites as breeding habitat for birds in the jarrah forest of south-western Australia

Summary A survey was undertaken lo assess 5 to 10-year-old rehabilitated bauxite minesite vegetation as suitable habitat for birds while breeding during spring in the jarrah (Eucalyptus marginata) and marri (E. calophylla) forest at Jarrahdale. Western Australia. The minesites had been rehabilitated and revegetated with local shrub species and a mix of local and eastern eucalypts resistant to the root rot fungus Phytophthora cinnamomi. Twenty-one species of birds used the former minesites for foraging or hunting while breeding; twelve of these were found nesting or rearing fledglings in the revegetation. Among the breeders were four understorey dwelling species which were otherwise uncommon in surrounding upland forest or (in two cases) confined in stream zone undergrowth. Total densities of all pairs or groups breeding in minesites were similar to those in nearby forest. Breeding territories often spanned areas of both minesite and forest around the edge of pits. Eleven other species were found breeding ...