Time filter

Source Type

Kensington, Australia

Bishop C.L.,University of Queensland | Wardell-Johnson G.W.,Curtin University Australia | Williams M.R.,7 Dick Perry Avenue
Journal of Vegetation Science | Year: 2010

Question: Does the introduced pathogen Phytophthora cinnamomi change Banksia woodland α- or β-diversity and what are the implications for species re-colonization? Location: High rainfall zone of the Southwest Australian Floristic Region (SWAFR). Methods: We measured pathogen-induced floristic change along a disease chronosequence, and re-sampled historic quadrats in Banksia attenuata woodlands of the SWAFR. The chronosequence represents three disease stages: (1) healthy vegetation with no disease expression; (2) the active disease front; and (3) diseased vegetation infected for at least 15 years. Comparative data were obtained by resampling diseased plots that were historically disease-free when established in 1990. Results: β-diversity differed substantially for both chronosequence and historic data, while α-diversity was maintained, as measured by plot species richness and Simpson's reciprocal index. Species of known pathogen susceptibility were significantly reduced in cover-abundance, including the structurally dominant species; Banksia attenuata, B. ilicifolia and Allocasuarina fraseriana. Although these species remained present on diseased sites, there were overall reductions in canopy closure, leaf litter and basal area. These declines were coupled with an increase of species with unknown susceptibility, suggesting potential resistance and capacity to take advantage of altered site conditions. Conclusions: This study highlights the ability of an introduced plant pathogen to alter community floristics and associated stand variables. Species cover-abundances are unlikely to recover due to a reduced seed source, altered site conditions and pathogen persistence at the landscape level. However, maintenance of α-diversity suggests continued biological significance of Phytophthora-affected sites and the formation of novel ecosystems, themselves worthy of conservation. © 2010 International Association for Vegetation Science. Source

Wardell-Johnson G.W.,Curtin University Australia | Calver M.,Murdoch University | Burrows N.,7 Dick Perry Avenue | Di Virgilio G.,Curtin University Australia | Di Virgilio G.,University of New South Wales
Pacific Conservation Biology | Year: 2015

The environment of the northern jarrah (Eucalyptus marginata) forest (NJF) of Mediterranean-climate, south-Western Australia is characterised by deeply weathered soil profiles and low fertility, reflecting long geological stasis. This fire-prone environment is characterised by primary forests of low productivity but high biomass. Since European settlement (1829), the NJF has been structurally transformed by deforestation and resource extraction, including logging and mining (principally for bauxite). Rainfall has declined by 15-20% since 1970, with projections for further decline. A new hydrological regime foreshadows regolith drying, with a changed climate leading to more unplanned, intense fires. Declining productivity, coupled with rehabilitation more suited to a wetter climate, places stress on tree growth and compromises biodiversity. Thus, ecological disruption likely follows from interactions between climate change and historical exploitation. The complex challenges posed by these interactions require multifaceted and novel solutions. We argue that under drying conditions, maintenance of productivity while conserving biodiversity can best be achieved by changing the focus of rehabilitation to the understorey. This would coincide with protecting and restoring surrounding unmined forest with emphasis on the overstorey. Presently, state-of-the-science rehabilitation seeks to restore jarrah forest, following bauxite mining. This goal is unlikely to be achievable across extensive areas under climate change projections. Rather, a focus on restoring understorey following mining would provide a more positive water balance in the wider forest matrix. This approach recognises loss of forest values through mining, but anticipates conservation of biodiversity and important elements of forest structure by minimising ecologically unacceptable disturbance to surrounding forest. © CSIRO 2015. Source

Spencer P.B.S.,Murdoch University | Giustiniano D.,Murdoch University | Hampton J.O.,Murdoch University | Gee P.,Rural Solutions | And 4 more authors.
Journal of Wildlife Management | Year: 2012

The dromedary camel (Camelus dromedarius) is a significant invasive species in Australia. It is an unusual pest species that is of large body size with relatively low fecundity compared with other pest species. Camels are highly adapted to the arid regions that characterize a large proportion of Australia and occupy an almost completely undisturbed area of ≥3 million km 2. They have no history of invasion elsewhere in the world. Despite this, their population has been expanding at approximately 80,000 camels per annum, with the most recent estimate of population size around 1,000,000 individuals. We employed a landscape-genetic approach to evaluate the population structure and molecular ecology of Australian camels. We combined mitochondrial control region sequence (n = 209 animals) with 18 microsatellite markers to profile over 800 adult camels to identify the presence of a single panmictic population. We showed that demographically defined neighborhoods for wild camels are about 200 km; this value was supported by home range estimates. Distances greater than this display no pattern of isolation by distance across the Australian continent. The result is the largest single geographical population so far recorded for an invasive species in Australia. This pattern may be explained by the impressive and near-nomadic dispersal pattern of camels, in combination with an unpredictable environment virtually devoid of barriers to movement and predatory suppression. Although it is technically feasible, the reality is that it would not be economically or politically viable to have continental eradication of wild camels in Australia because of the vast size and movement dynamics of the camel population. As such, we advocate a change away from an expensive solution to an intractable reduction program (that is almost entirely focused on protection of biological refugia) and moves to include cultural, economic, and biodiversity asset protection for the management of this most unorthodox of invasive species. © 2012 The Wildlife Society. Source

Burrows N.,7 Dick Perry Avenue | Middleton T.,Brain Street
Fire Ecology | Year: 2016

A fire sensitive plant, Banksia quercifolia R.Br., that often occurs as thickets embedded in forest landscapes in south-west Australia was exposed to repeated broad-scale fires at short intervals. Fire severity and patchiness was mapped using satellite imagery and the response of the B. quercifolia population monitored. Over the study period, the mean interval of fire in the landscape in which B. quercifolia occurred was 1.7 yr‑almost half the juvenile period of the species‑and the landscape fire frequency was six fires per decade. The population increased in response to episodes of fire escape and fire-caused mortality and consequent regeneration. Unlike surrounding vegetation, immature B. quercifolia thickets were not flammable under conditions of mild weather and moist fuels, so they burnt at a lower frequency than more flammable vegetation in the surrounding landscape, enabling the species to persist. When the thickets had developed sufficiently to burn, the plants had reached maturity and regenerated readily from seed. However, the juvenile period increased by 58 % following a period of 16 % below average rainfall, which has implications for fire management in a drying climate. © 2016, Association for Fire Ecology. All rights reserved. Source

Baldock J.,7 Dick Perry Avenue | Bancroft K.P.,7 Dick Perry Avenue | Williams M.,7 Dick Perry Avenue | Shedrawi G.,7 Dick Perry Avenue | And 2 more authors.
Ocean and Coastal Management | Year: 2014

Near real-time observation of sea temperature is an important management tool for monitoring the impacts associated with a changing climate on a range of marine communities particularly within marine protected areas. However, limitations exist when using data derived from satellite remote sensing as virtual stations are usually distant from areas of interest for management. Modelled sea surface temperature will, in most cases, provide a general over a large spatial scale rather than a specific prediction. Understanding the relationship between remotely sensed sea temperature and in situ temperature enables real-time management responses to sea temperature, in relation to both long-term changes and short-term anomalies, and their biological implications. Historically, the effects of most thermal stress events on marine communities have been observed opportunistically or realised well after the event, due to the use of in situ loggers and the associated time-lag between the event, logger retrieval and data interpretation. Understanding the susceptibility of marine communities to, and recovery from, thermal stress events requires reliable estimation of the events in real time at local spatial scales. To further understand the relationship between in situ and satellite derived sea temperatures, and develop a real-time monitoring tool, a simple linear interpolation was undertaken to estimate local in situ temperature, at depth, using near real-time satellite derived sea surface temperatures. The US National Oceanic and Atmospheric Administration's (NOAA) Coral Reef Watch 50km sea surface temperature (SST) data was selected because of its readily available and continual near real-time update of sea surface temperatures worldwide. In situ temperature logger data from four Western Australian marine protected areas (MPAs) were used to develop and test the linear interpolation. Utilising the model, we were able to successfully estimate the in situ temperature to within ±1°C, at least 78% of the time, including temperature anomalies experienced in February 2011, at sites of interest across the four MPAs. This simple linear interpolation model will be used to improve near real-time estimates of temperature for broadscale monitoring of MPAs throughout Western Australia, allowing greater understanding and informed management response to long-term changes and short-term temperature anomalies. Future expansion of the sites monitored, improved satellites resolution and an annual review of data sources will ensure that the data used for management of this threat to water quality remains at the highest level of accuracy possible with the available data. © 2014 Elsevier Ltd. Source

Discover hidden collaborations