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Bentley, Australia

McCaw W.L.,Locked Bag
Forest Ecology and Management | Year: 2013

Prescribed fire has been used in a coordinated manner to manage fuels in eucalypt forests of southern Australia since the 1950s. The impetus for planned use of fire arose from the need to reduce the impact of extensive, high intensity fires on life, property and commercial forest values. Prescribed fire is increasingly recognised as also playing an important role in mitigating undesirable effects of high intensity fires on environmental values including soil, water and biodiversity. Critical elements for an effective prescribed fire program include a sound understanding of fire behaviour, an experienced and flexible workforce, and organisational commitment to adaptive management involving planning, monitoring and applied research. Implementation of prescribed fire programs has been closely linked with, and dependent upon, the development of burning guides for particular forest types through empirical field research. The contribution of prescribed fire to mitigating the effects of extensive, high intensity fires can be quantified in a variety of ways using basic combustion science, well-documented case studies, analysis of fire statistics, and simulation. Fuel reduction can improve the safety, efficiency and effectiveness of fire suppression, although these effects may be subtle and difficult to measure. Social and political factors can significantly influence the conduct and effectiveness of prescribed fire programs, and effective engagement with the community during planning, implementation and post-fire monitoring phases is essential to ensure that the role of prescribed fire in land management is properly recognised and understood. © 2012 Elsevier B.V.

Species composition, size class distribution and developmental stage of canopy and mid-storey tree species were measured at 48 sampling grids in jarrah (Eucalyptus marginata) forest for the FORESTCHECK monitoring project. Other site attributes quantified at each grid included litter loading and coarse woody debris volume, and concentrations of N, P and K in surface soil and eucalypt foliage. Grids were located in stands treated to release regeneration by gap creation (n = 14), to establish regeneration by shelterwood harvesting (n = 12) and in stands where the outcome of harvesting was a selective cut (n = 3). Grids were also located in coupe buffers (n = 4) and in external reference forest (n = 15) that had not been harvested since 1960, with eight grids having no record of previous harvesting or evidence of cut stumps. Live eucalypt basal area in external reference forest and coupe buffers averaged 41 m 2 ha -1 (range 13-78 m 2 ha -1), with marri (Corymbia calophylld) contributing more than half the basal area on some grids in the Jarrah South and Jarrah Blackwood Plateau ecosystems. On average, basal area was reduced by 14 m 2 ha -1 to 17 m 2 ha -1 in shelterwood stands and by a similar amount in selectively cut stands. Basal area was reduced by 22 m 2 ha -1 to 9 m 2 ha -1 in areas cut to gap release. Mature trees greater than 70 cm diameter were retained at a rate of six to seven per hectare in harvested stands. Basal area ingrowth following harvesting averaged 0.5 m 2ha -1 y -1 of jarrah and 0.3 m 2ha -1 y -1 of marri. Harvesting increased the volume of coarse woody debris, with the largest amounts present in stands cut to gap release. The volume of woody debris <250 mm in diameter was significantly less in external reference forest that had never been harvested than in shelterwood or gap release stands. Data collected during the initial 5 y of the FORESTCHECK project demonstrate that gap release treatment has resulted in fully stocked stands with a developing cohort of saplings. Shelterwood treatment has been applied conservatively with a tendency to retain more basal area than required by the silvicultural guidelines, and in areas that may already have had sufficient ground coppice to allow for satisfactorily regeneration by gap release. Shelterwood silviculture does not necessarily result in establishment of sufficient seedlings to satisfy regeneration stocking standards within 10 y of treatment, but further episodic recruitment following fire is expected to achieve this over the longer term.

Cruz M.G.,CSIRO | Cruz M.G.,Bushfire Cooperative Research Center | McCaw W.L.,Locked Bag | Anderson W.R.,University of New South Wales | And 2 more authors.
Environmental Modelling and Software | Year: 2013

Knowledge of fire behaviour potential is necessary for proactive management of fire prone shrublands. Data from two experimental burning programs in mallee-heath shrublands in semi-arid southern Australia were used to develop models for the sustainability of fire spread, fire type, i.e., surface or crown fire, forward spread rate and flame height. The dataset comprised 61 fires burned under a wide range of weather conditions. Rates of fire spread and fireline intensity varied between 4 and 55 m min-1 and 735 and 17,200 kW m-1 respectively. Likelihood of sustained fire spread and active crown fire propagation were modelled using logistic regression analysis. Fire spread sustainability was primarily a function of litter fuel moisture content with wind speed having a secondary but still significant effect. The continuity of fine fuels close to ground level was also significant. Onset of active crowning was mostly determined by wind speed. Rate of fire spread was modelled separately for surface and crown fires through nonlinear regression analysis with wind speed, litter fuel moisture content and overstorey canopy cover as significant variables. Flame height was modelled as a function of fireline intensity. A model system to predict the full range of fire behaviour in mallee-heath shrubland is proposed relying on a combined method that links the surface and crown fire rate of spread models. This model system was evaluated against independent data from large scale prescribed burns and wildfires with encouraging results. The best models for fire-spread sustainability and active crown fire propagation predicted correctly 75% and 79% respectively of the fires in the evaluation dataset. Rate of spread models produced mean absolute percent errors between 53% and 58% with only small bias. The models have applicability in planning and conducting prescribed fire operations but can also be extended to produce first order predictions of wildfire behaviour. © 2012 Elsevier Ltd.

Dominiak B.C.,Locked Bag | Dominiak B.C.,Macquarie University
Annals of the Entomological Society of America | Year: 2012

The fruit fly Bactrocera tryoni (Froggatt) (Diptera: Tephritidae) is a species of significant quarantine concern to many countries. Currently, B. tryoni is found in parts of Australia and on some Pacific islands. Understanding dispersal behavior is important for the development of scientifically justified trade restrictions or quarantine distances for B. tryoni. These distances ensure adequate protection for overseas markets while also ensuring that growers sufficiently distant from the affected area are able to retain unrestricted access to markets. This review considers scientific data on dispersal and uses this information to make recommendations for appropriate quarantine distances. Most studies conclude that the lifetime dispersal distance of this species rarely exceeds 1 km, although three studies indicate that longer dispersal distances of a small number of individuals may occasionally occur. These short dispersal distances are consistent with findings for other fruit fly species. Triggers for long-distance dispersal, the fate of these individual flies, nutritional requirements to support this dispersal, and reasons for discrepancies in the dispersal distances reported in different studies are reviewed. Reasons for the inability of B. tryoni to establish along southern parts of the east coast of Australia before European colonization are postulated. A proposed quarantine distance is based on the scientific basis of the mean and 3 SD, with a 3-fold level of protection based on distance. It is proposed that an area contained by a circle with a radius of 1.2 km is a reasonable quarantine area for B. tryoni outbreaks where flies are contained within 200 m of an epicenter. Where total trappings are contained within 400 m of the epicenter, a quarantine distance of 2.4 km is recommended. Three other quarantine distances are proposed based on the formula by using the mean. © 2012 Entomological Society of America.

Robinson R.M.,Locked Bag | Williams M.R.,Bentley Delivery Center
Australian Forestry | Year: 2011

Species richness, abundance and composition of epigeous macrofungi were monitored at 48 grids across four jarrah (Eucalyptus marginata) forest ecosystems in south-west Western Australia as part of an integrated monitoring project to examine responses to different timber harvesting and regeneration treatments. Forest that had never been harvested or had not been harvested for over 40 years was used as a reference, and compared to forest that had undergone shelterwood/selective cutting and gap release treatment after 1988. Silvicultural treatment also included post-harvest burning. All epigeous species of macrofungi and their abundance were recorded from autumn surveys at each grid. A total of 450 species were recorded. Overall mean species richness and abundance was similar but the composition of species assemblages contributing to macrofungal communities differed significantly between silvicultural treatments and reference forest. Sixty-nine species were restricted to reference forest while 35 were restricted to shelterwood/selective cut and 62 to gap release treatment. In all treatments, the overall mean number of species per grid recorded fruiting on soil was 2-4 times higher than that recorded on litter or wood. Species richness of sporophores recorded on both soil and litter was similar for all treatments, but was significantly lower on wood in reference forest compared to the gap release treatment. Mean sporophore abundance was significantly higher on litter and lower on wood in reference forest compared with silviculturally treated forest. Because fire is an integral part of jarrah forest silviculture, it was not possible to separate the singular effect that either tree removal or fire had on macrofungal communities. However, in different time-since-treatment classes the overall composition of species assemblages was different, but species richness and abundance for each silvicultural treatment were similar. Each forest ecosystem supported its own unique fungal community, which supports the concept of ecosystems in jarrah forest based on forest structure and understory vegetation resulting from variation in climate, soils and landforms. Current conservation policy and silviculture practice in jarrah forest produces a landscape mosaic containing early succession stands through to mature forest across the landscape, which is important for the maintenance of fungal biodiversity. Much of the fungal population in jarrah forest, however, remains unknown and only a long-term commitment to survey and monitoring will improve knowledge on the diversity and ecology of these important organisms and ensure their consideration in future management decisions.

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