Karri Research Articles

Fuel weight and understorey hazard dynamics in mature karri (Eucalyptus diversicolor) forests in southwest Western Australia

ABSTRACT Fuel properties influence the behaviour of forest fires, so understanding how these change with time since fire is important for appraising the bushfire threat and planning and implementing bushfire mitigation operations. A space-for-time study in mature karri forests with fuel ages ranging from 1 to 92 years demonstrated that total fine-fuel weight (TFFW) increased with time since fire for about 30 years then plateaued at a mean value of about 50 t ha−1. For fuels older than four years, on average, 74% of TFFW was in the surface fuel layer (the litterbed) and 17% was in the near-surface layer (up to 1 m above the surface layer). Live understorey vegetation contributed only about 6% to TFFW. Predicting TFFW from time since fire was improved by including karri tree basal area. Mean understorey height (Uht) increased with time since fire, peaking at 6 m after about 30 years, then declining to about 4 m after 92 years. Mean understorey hazard (Uhaz), derived from Uht plus the proportion (%) of dead fuel in each fuel layer, followed a similar trend, peaking at 20–30 years post-fire, then declining. Although Uhaz had declined by 36% from the maximum value by 60+ years post-fire, it was 27% higher than the Uhaz value for young fuels (1−<5 years old). For a mean prescribed-burn interval of eight years, 50% of the forest fuel will be ≤four years old and so will be carrying about ≤19 t ha−1 of fine fuel (≤38% of the maximum value), with a Uhaz value of about <3.56 (<50% of the maximum value). Fuel weight and Uhaz directly influence fire intensity, flame size, spotting potential and rate of spread. Therefore, prescribed burning, done strategically and at the appropriate temporal and spatial scales, will make bushfires less damaging and easier and safer to suppress.

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.

Effect of thinning on growth and allometry of Eucalyptus diversicolor

Karri (Eucalyptus diversicolor F. Muell.) forest is an endemic forest type of southwest Western Australia (SWWA), noted for having the tallest trees in the region, and providing commercial, ecological and conservation value. To inform management aimed at optimising these values, a thinning trial was commenced in 1992. The aim of this study was to evaluate the effects of thinning on individual tree growth, stand level growth and allometry of karri trees in even-aged stands. Mixed effect models were used to compare the effect of different levels of thinning on individual tree growth and stand level growth of karri. We developed allometric equations modelling the relationship between diameter at breast height (DBH) and height, and tested whether thinning affected this allometric relationship. Thinning enhanced DBH, height and crown width (CW) growth of individual trees by up to 149%, 56% and 108% respectively in heavily thinned stands, with stand basal area growth optimised at retained basal areas of 13 m2 ha−1. Thinning had a significant effect on allometry of DBH with height, height-DBH ratio (HDR) and CW. Reduction in stand density through thinning from below increased diameter growth of individual trees. Stand level basal area growth is optimised at an intermediate level of thinning. Thinning can be a good management tool for even-aged karri forest because it may promote the diameter and thereby basal area growth, good health of individual trees, and potential ecological benefits including accelerated development of larger tree crowns typical of mature forest.

Tommaso Jucker

Tommaso Jucker

Fire severity impacts on tree mortality and post-fire recruitment in tall eucalypt forests of southwest Australia

Wildfires are predicted to increase in both frequency and severity across Mediterranean climate regions worldwide. While many Mediterranean-type ecosystems are considered broadly fire tolerant, there is little understanding of how differences in fire severity affect plant community dynamics, tree mortality and recruitment. In the tall karri (Eucalyptus diversicolor F. Muell) forests of southwest Australia, low to moderate severity wild and prescribed fires are relatively common. Mature karri trees survive these events and recover rapidly due to their thick bark and ability to prolifically resprout from epicormic buds. However, despite a projected increase in the frequency of high severity wildfires, the impact of such extreme fires on tree mortality and understory community composition is not well understood. We used a large and severe wildfire event in southwest Australia to assess how fire severity impacted recruitment and survival of karri seedlings, the mortality of mature karri trees, and the composition of the understory plant community. Mature karri tree mortality was 87% greater at sites burnt at high severity compared to unburnt sites and sites burnt at low severity. Understorey plant community composition of burnt sites was different to unburnt sites, driven largely by significant shifts in dominance. Notably, the usually dominant understorey shrub Trymalium odoratissimum was entirely absent from forests burnt at extreme high severity. These results indicate that karri forests burnt at very high severity undergo changes in stand structure that will persist for many decades, and that the structure and species composition of the understorey may also be altered significantly. This indication of a possible fire severity threshold is consistent with the findings of recent studies in other Mediterranean climates following catastrophic wildfires. This study highlights the need for further research into the effects of severe wildfire on forest ecosystems that are otherwise considered fire tolerant.

Impacts of climate change on eucalypt distributions in Australia: an examination of a recent study

ABSTRACTA recent study examined the possible impacts of climate change on 657 Australian eucalypt species in the period to 2085 using species distribution modelling (SDM). The study predicted that ‘within the next 60 years the vast majority of species distributions (91%) across Australia will shrink in size (on average by 51%)’. The purpose of the present paper is to demonstrate some of the strengths and weaknesses of this previous study. Its main strength is that it identifies relatively hot and dry areas of species distributions that may be vulnerable under climate change. Its main weakness is that the individual analyses tend to overestimate the areas of species natural distributions. Consequently, the predicted percentage losses of species distribution areas are unreliable. To illustrate the problem the freely available Atlas of Living Australia (ALA) is used examine two contrasting species (Eucalyptus diversicolor and E. nitens) in detail, so readers will be able to apply similar methods to any eucalypt species of interest. For well-known species a more reliable assessment of likely losses of distributional area under climate change may be obtained by applying the results of the SDM analysis, but assuming that ALA occurrences within 25 km x 25 km areas are an accurate representation of present natural distributions. Using this approach the estimated loss of area of natural distribution by 2085 for both E. diversicolor and E. nitens are less than half the estimates provided by the original paper. For lesser-known species, it is concluded that an additional SDM analysis is required to provide a closer representation of species natural distributions, to which the original SDM climate change results, which attempt to capture some of the species adaptability/plasticity, could be applied.

Neocolonialism and Health Care Access among Marshall Islanders in the United States.

In the Marshall Islands, a history of extensive nuclear weapons testing and covert biomedical research, coupled with the U.S.'s ongoing military presence in the country, has severely compromised the health of the local population. Despite the U.S.'s culpability in producing ill health along with high rates of emigration from the islands to the mainland United States, the large portion of Marshallese who reside in the United States face substantial barriers to accessing health care. Drawing from ongoing field research with a Marshallese community in Arkansas, this article explores the multifaceted impediments that U.S.-based Marshall Islanders face in receiving medical treatment. Calling on an expansive and inclusive notion of neocolonialism, I argue that Marshallese structural vulnerability with regard to health and health care treatment derives from their status as neocolonial subjects and from their limited claims to health-related deservingness associated with this status. [Marshall Islanders, health care access, neocolonialism, radiation exposure, immigrant health] L̗ōmn̗ak ko rōttin̗o: Ilo M̗ajel̗, juon bwebwenato kōn kōmmālmel im nuclear baam̗ ko im ekkatak ko rōttin̗o̗ kōn wāwein an baijin ko jelōt armej, barāinwōt an to an ri tarinae ro an Amedka pād ilo aelōn̄ kein, em̗ōj an jelōt ājmour an armej ro ilo aelōn̄ kein. Men̄e alikkar bwe Amedka in ear jino nan̄inmej kein im ej un eo armej rein rej em̗m̗akūt jān āne kein āne er n̄an ioon Amedka, elōn̄ iaan ri M̗ajel̗ rein rej jelm̗ae elōn̄ apan̄ ko n̄an aer del̗o̗n̄e jikin ājmour ko. Jān ekkatak eo ej bōk jikin kiō, jerbal in ej etali kabōjrak rak kein rōlōn̄ im armej in M̗ajel̗ ro ioon Amedka in rej jelm̗ae ilo aer jibadōk lo̗k jikin taktō. Ilo an kar Amedka jibadōk juon jea eo eutiej imejān lal̗ in, ij kwal̗ok juon aō akweelel bwe apan̄ ko an armej in M̗ajel̗ ikijjeen ājmour im jikin taktō ej itok jān aer kar ri kōm̗akoko ilo an kar Amedka lelōn̄ l̗o̗k etan ilo mejān lal̗ im jān aer jab pukot jipan kein ej aer bwe kōn jōkjōk in.

Forest as Place in the Album "Canopy": Culturalising Nature or Naturalising Culture?

Forest as Place in the Album "Canopy": Culturalising Nature or Naturalising Culture?

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 &amp; 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.

The Admonitions of St. Francis: Sources and Meanings by Robert J. Karris, OFM

The Admonitions of St. Francis: Sources and Meanings by Robert J. Karris, OFM

Assessment of Microwave Bending Capabilities for Australian Wood Species

An innovative wood bending technology has been developed by the University of Melbourne, within the Cooperative Research Centre for Wood Innovations, which involves the microwave softening of wood components to make them pliable for bending, the use of an automated bending machine, and microwave drying of bent furniture components. This article presents the results of a study that assessed bending quality and that determined the minimum radius of bending curvature of eight plantation and regrowth Australian timbers using the microwave wood bending process: Eucalyptus nitens, Eucalyptus saligna, Eucalyptus marginata, Eucalyptus diversicolor, Pinus radiata, Nothofagus cunninghamii, Atherosperma moschatum, and Acacia melanoxylon. Based on the results of the study, the microwave bending performance of the wood species was rated as follows: (1) E. diversicolor, very good (sanding or small amount of machining was required); (2) P. radiata, Atherosperma moschatum, and E. nitens, decent (machining was needed); (3) Acacia melanoxylon and N. cunninghamii, satisfactory (fairly large failures occurred but these were removed by machining); and (4) E. saligna and E. marginata, very bad (large failures which could not be removed by machining). Overall, the results of the study on the bending performance capabilities of plantation and regrowth Australian timbers showed several differences compared with the literature data relating to the bending abilities of the relevant old growth timbers.

First record of Cryptosporiopsis actinidiae in Australia

Cryptosporiopsis actinidiae, the cause of post-harvest rot in yellow-fleshed kiwifruit in New Zealand, was isolated from freshly sawn Eucalyptus diversicolor scantling in the south-west of Western Australia in 1986. This isolate was identified by rDNA internal transcribed spacer sequencing in 2006. It is the first record of C. actinidiae in Australia.

Causes of incipient rot and rot in regrowthEucalyptus diversicolor(karri) trees

Eucalyptus diversicolor(karri) is the second most important commercial timber tree in Western Australia. Sawlogs from regrowth trees often have a discoloration in the heartwood that is more abundant than in sawlogs from mature trees. Other symptoms in regrowth logs include white rot, white pocket rot and brown rot. Fungal isolations and pathogenicity tests were conducted to determine whether this discoloration was incipient rot, and if so, what caused it and which rot(s) would eventually develop. A combined sample of 329 discs from recently felled trees and freshly cut scantling had discoloration in 48%, white rot in 14%, white pocket rot in 12% and brown rot in 4% of pieces of wood.Hymenochaete semistupposawas isolated from 22% of discoloured wood and 39% of white pocket rot samples.Stereum hirsutumwas isolated from 4% of discoloured wood and 13% of white rot samples. Koch's postulates in regrowth karri trees showed thatH. semistupposacaused extensive discoloration, with white pocket rot developing in the heartwood within 4 years, whileS. hirsutumcaused extensive discoloration, with white rot developing in both the heartwood and sapwood within 2 years. It was concluded that the discoloration was incipient rot, which would eventually develop into either white rot or white pocket rot.

Epigeous macrofungal succession in the first five years following a wildfire in karri (Eucalyptus diversicolor) regrowth forest in Western Australia

Abstract Following a wildfire in 17–25‐year‐old regrowth karri (Eucalyptus diversicolor) forest in the southwest of Western Australia, plots were established in burnt and similarly aged unburnt forest to monitor the fruiting of macrofungi. Thirty‐six plots on 10 sites (five burnt, five unburnt) were surveyed over a 5‐year period. Plots were surveyed every 2 weeks in the macrofungal fruiting season (April to October) and monthly for the remainder of each year. A total of 332 species were recorded. Fire did not impact significantly on mean species richness. However, a distinct mycoflora was recorded on burnt sites, and species composition on burnt sites changed substantially for each year following the fire and after 5 years was still different from that on unburnt sites. Nineteen percent of species recorded were regarded as being present as a direct result of the fire. The study also demonstrated the variable nature of macrofungal sporophore production in the absence of disturbance and the importance of regular sampling. Five distinct succession groups of post‐fire fungi were recognized. The adaptive traits of post‐fire fungi in relation to fire and the management of fire for macrofungal diversity are discussed.

Comparison of the occurrence of rot in sawlogs from regrowth and mature stands of Eucalyptus diversicolor (karri)

SummaryKarri (Eucalyptus diversicolor) timber from old-growth forest has been highly valued for heavy engineering construction, special purpose rail track timbers, scantling for housing, mine guides, joinery, furniture and flooring. With changes to forest management, sawlogs from mature stands have been supplemented by sawlogs from regrowth stands. A survey was conducted to compare the quality of sawlogs from mature and regrowth stands in relation to incipient rot, established rot, other defects and market expectations for this species. Sawmill surveys of sawlogs from regrowth and mature stands were carried out in 1987 and 1992 respectively. These surveys showed that there was significantly more incipient rot, known locally as brown wood, and or wood rot in regrowth sawlogs than in sawlogs from mature stands, while there was significantly less kino in regrowth sawlogs. The most common defects in both log classes were the presence of kino and incipient rot. The most frequent infection points for wood rot fungi were branch stubs, borer galleries and scars (which may have been caused by Armillaria infection, fire damage or mechanical damage). Infection associated with branching was more common in regrowth sawlogs than in sawlogs from mature stands. In both log classes, scattered pockets of incipient rot and or established rot were most frequently associated with borer galleries. In regrowth sawlogs, when at least two-thirds of the whole cross-section of the log was affected by incipient rot and or established rot, it was associated with scars resulting from fire, Armillaria or mechanical damage. Since this survey was conducted, changes in Western Australian government policy have resulted in only regrowth forest being available for harvest.

‘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.

Floristic patterns and disturbance history in karri (Eucalyptus diversicolor: Myrtaceae) forest, south-western Australia: 2. Origin, growth form and fire response

We examined the influence of disturbance history on the floristic composition of a single community type in karri forest, south-western Australia. Cover-abundance of 224 plant species and six disturbance and site-based environmental variables were recorded in 91, 20 m x 20 m quadrats. Numerical taxonomic and correlation approaches were used to relate these and 10 plant species-group variables based on origin, growth form and fire response. Ordination revealed no discernable pattern of sites based on floristic composition. However, all 10 species-group variables were significantly correlated with the ordination axes. Species richness within these groups varied with category and with respect to many of the disturbance and site variables. We encountered low diversity of vascular plants at the community level and limited diversity of growth forms. Thus most species were herbs (62.1%) or shrubs (30.3%), and there were no epiphytes and few species of trees or climbers. Although many introduced species were recorded (18.3% of all taxa), virtually all (83%) were herbs that demonstrated little persistence in the community, and there was limited evidence of transformer species. Time-since-fire (and other disturbance) influenced species richness more than the number of recent past fires because of a high proportion of ephemerals associated with the immediate post-fire period. Long-lived shrubs with soil stored seed dominate numerically, and in understorey biomass in comparison with neighboring vegetation types because of their greater flexibility of response following irregular, but intense disturbance events. However, interactions between nutrient status, regeneration mechanisms and community composition may be worthy of further investigation. (c) 2006 Elsevier Masson SAS. All rights reserved.

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.

Life history of the white-breasted robin, Eopsaltria georgiana (Petroicidae), in south-western Australia

The white-breasted robin, Eopsaltria georgiana, is endemic to south-western Australia. We studied breeding, dispersal and survival in known groups from 1978 until 1987, with some groups followed until 1992, in Eucalyptus diversicolor (karri) forest near Manjimup, Western Australia. E. georgiana bred cooperatively, with 66% of groups including one or more birds in addition to the breeding pair (mean group size 3.1); these helpers were predominantly males and assisted the senior male in feeding the female on the nest and the young and defending the territory. The survival of adults was high (males 86%; females 79%). Breeding territories and groups persisted from year to year, although in the non-breeding season, males ranged more widely. Dispersal was female-biased; most females and some males dispersed in their first year. Divorce was rare; breeding males that disappeared were replaced by a helper from within the group if one was present, and females were replaced from outside the group. Eggs were laid between July and December. Clutch size was almost always 2, incubation lasted 16–17 days and nestlings fledged 13–14 days later. Juveniles were dependent on adult provisioning for 6–8 weeks. We found no parasitism by cuckoos. Of 429 nests found, 74% fledged at least one young, and overall nesting success calculated by the Mayfield method was 63%. The median time between initiation of two successive clutches was 54 days, and 52% of females renested after fledging one brood; at least two broods per year were fledged by 44% of females. Groups produced a mean of 2.8 fledglings, 1.3 independent young and 0.7 yearlings per year. The most productive groups were those with two or more helpers on high-quality territories, but we could not separate the effects of helpers and territory quality. E. georgiana has the 'slow' life history typical of many Australian passerines – cooperative breeding, sedentary, resident all year round in an equable habitat that promotes high survival of breeding adults. Their low reproductive rate produces a small crop of yearlings, some of which may stay in the parental home range.

Short-term impact of thinning and fertilizer application on Armillaria root disease in regrowth karri ( Eucalyptus diversicolor F. Muell.) in Western Australia

The incidence of Armillaria root disease was recorded during routine measurement of a silvicultural experiment designed to test the effect of thinning and nitrogen fertilizer application on the growth of karri regenerated after clearfelling. The experiment was established in 1984, when the stand was 12-year-old. Ten years after thinning, the level of disease increased significantly with increased thinning intensity, and disease accounted for 51% of the mortality in the plots thinned to 200 stems/ha. Fifteen years after thinning, the level of infection had increased in all treatments but was still significantly lower in the unthinned treatment. In the thinned treatments, 54–63% of the trees ranked in the largest 200 stems/ha were infected, and 50–100% of the mortality within these trees was attributed to Armillaria luteobubalina. In the unthinned treatment, no mortality within the dominant trees was associated with disease. Ten years after thinning and fertilizer treatments, it could not be determined whether fertilizer application had had any effect on the level of disease. Whole tree thinning, which results in stump and root removal, is discussed as a viable management option in high-quality karri regrowth stands infested with A. luteobubalina.