Trent D. Penman

Prescribed burning: how can it work to conserve the things we value?

Prescribed burning is a commonly applied management tool, and there has been considerable debate over the efficacy of its application. We review data relating to the effectiveness of prescribed burning in Australia. Specifically, we address two questions: (1) to what extent can fuel reduction burning reduce the risk of loss of human life and economic assets posed from wildfires? (2) To what extent can prescribed burning be used to reduce the risk of biodiversity loss? Data suggest that prescribed burning can achieve a reduction in the extent of wildfires; however, at such levels, the result is an overall increase in the total area of the landscape burnt. Simulation modelling indicates that fuel reduction has less influence than weather on the extent of unplanned fire. The need to incorporate ecological values into prescribed burning programmes is becoming increasingly important. Insufficient data are available to determine if existing programs have been successful. There are numerous factors that prevent the implementation of better prescribed burning practices; most relate to a lack of clearly defined, measurable objectives. An adaptive risk management framework combined with enhanced partnerships between scientists and fire-management agencies is necessary to ensure that ecological and fuel reduction objectives are achieved.

Divergent responses of fire to recent warming and drying across south‐eastern Australia

The response of fire to climate change may vary across fuel types characteristic of differing vegetation types (i.e. litter vs. grass). Models of fire under climatic change capture these differing potential responses to varying degrees. Across south-eastern Australia, an elevation in the severity of weather conditions conducive to fire has been measured in recent decades. We examined trends in area burned (1975-2009) to determine if a corresponding increase in fire had occurred across the diverse range of ecosystems found in this part of the continent. We predicted that an increase in fire, due to climatic warming and drying, was more likely to have occurred in moist, temperate forests near the coast than in arid and semiarid woodlands of the interior, due to inherent contrasts in the respective dominant fuel types (woody litter vs. herbaceous fuels). Significant warming (i.e. increased temperature and number of hot days) and drying (i.e. negative precipitation anomaly, number of days with low humidity) occurred across most of the 32 Bioregions examined. The results were mostly consistent with predictions, with an increase in area burned in seven of eight forest Bioregions, whereas area burned either declined (two) or did not change significantly (nine) in drier woodland Bioregions. In 12 woodland Bioregions, data were insufficient for analysis of temporal trends in fire. Increases in fire attributable mostly to warming or drying were confined to three Bioregions. In the remainder, such increases were mostly unrelated to warming or drying trends and therefore may be due to other climate effects not explored (e.g. lightning ignitions) or possible anthropogenic influences. Projections of future fire must therefore not only account for responses of different fuel systems to climatic change but also the wider range of ecological and human effects on interactions between fire and vegetation.

Modelling the determinants of ignition in the Sydney Basin, Australia: implications for future management

Variations in area burnt by fire are governed by four processes: biomass growth, availability to burn, fire weather and ignitions. Insight into these how these processes are shaped by biophysical and human influences is required to underpin the development of effective management strategies. Patterns of natural and arson ignitions were examined within the densely populated Sydney region of south-eastern Australia to determine the extent to which management can alter the risk of ignition. Arson ignitions were more likely on ridges in association with human infrastructure, i.e. roads and houses. Lightning ignitions also occurred more frequently on ridges, but at greater distances from human infrastructure. These patterns are consistent with those reported in studies from forested regions in the northern hemisphere. Fuel age had a variable effect with lightning more likely in older fuels (>25 years) and arson more likely in younger fuels (<10 years). Probability of both ignition types increased under more severe fire weather. Climate change is predicted to increase the severity of fire weather and is therefore likely to result in an increase in ignition frequency in the Sydney Basin. Urban expansion is also likely to have significant effects on ignitions and resultant risks to people and property via an increase in the probability of arson ignitions.

Detecting extinction risk from climate change by IUCN red list criteria

Anthropogenic climate change is a key threat to global biodiversity. To inform strategic actions aimed at conserving biodiversity as climate changes, conservation planners need early warning of the risks faced by different species. The IUCN Red List criteria for threatened species are widely acknowledged as useful risk assessment tools for informing conservation under constraints imposed by limited data. However, doubts have been expressed about the ability of the criteria to detect risks imposed by potentially slow-acting threats such as climate change, particularly because criteria addressing rates of population decline are assessed over time scales as short as 10 years. We used spatially explicit stochastic population models and dynamic species distribution models projected to future climates to determine how long before extinction a species would become eligible for listing as threatened based on the IUCN Red List criteria. We focused on a short-lived frog species (Assa darlingtoni) chosen specifically to represent potential weaknesses in the criteria to allow detailed consideration of the analytical issues and to develop an approach for wider application. The criteria were more sensitive to climate change than previously anticipated; lead times between initial listing in a threatened category and predicted extinction varied from 40 to 80 years, depending on data availability. We attributed this sensitivity primarily to the ensemble properties of the criteria that assess contrasting symptoms of extinction risk. Nevertheless, we recommend the robustness of the criteria warrants further investigation across species with contrasting life histories and patterns of decline. The adequacy of these lead times for early warning depends on practicalities of environmental policy and management, bureaucratic or political inertia, and the anticipated species response times to management actions.

Detecting pest and prey responses to fox control across the landscape using remote cameras

Context The red fox (Vulpes vulpes) is a widespread pest in southern Australia and is subject to control over large areas using poison baits to protect both agricultural and ecological assets. Foxes and their prey are often cryptic or in low densities, making it difficult to quantify the efficacy of control programs. Aims We explore the use of remote cameras to estimate the activity and spatial occupancy of foxes and potential mammalian and avian prey species before and after poison baiting in the Goonoo region, central New South Wales. Methods In the first of two studies, we set camera traps at 48 sites in forest and cleared areas, on and off tracks, during autumn 2009. In the second study, we placed camera traps in forest and cleared areas, on tracks only, at 100 sites covering an area of ~441 500 ha during winter 2009. We examined camera-trap rates of all species detected and the activity and site occupancy of a selected subset of species before and after poison baiting. Key results Camera traps indicated greater levels of fox activity on vehicular tracks than off them, with this difference being more marked in forest than in cleared agricultural land. Fox activity and occupancy were greater in agricultural land than in forest, with no effect of baiting detected at the landscape scale. Thirty-five other mammal and bird species were identified from photos, with activity for most being greater on than off tracks. Conclusions No clear effects of fox-baiting were detected on foxes or potential prey species in either study by either activity or occupancy. The lack of a baiting effect may reflect rapid recolonisation by foxes from unbaited areas, as bait placement is generally clustered in agricultural land, or the ready availability of alternative food (lambs or lamb carcasses) in some cleared areas. Implications Our results demonstrate that remote cameras provide a simple means of monitoring changes in fox activity and occupancy at the landscape level, and that these measures have great potential to quantify the success or otherwise of fox-control campaigns on both pest and prey species.

A proposal for accounting for biodiversity in life cycle assessment

Life cycle assessment (LCA) is a methodology for assessing the environmental impacts associated with products throughout their lifecycle. Many impacts are accounted for within the LCA framework, but to date biodiversity impacts have received little attention. There are a number of existing direct and indirect measures of biodiversity within the ecological field, some of which have the potential to be developed into a useable method for LCA. However, our assessment is that considerable development would be required and their implementation for LCA is not likely in the foreseeable future. Here an alternative approach is proposed for rapidly incorporating biodiversity impacts into LCA. The approach relies on expert opinions through a series of questions which aim to encapsulate the main issues relating to biodiversity within a disturbance impact framework. While the technique is in its infancy we outline a foundation for the approach and identify the steps required to develop this method for implementation into LCA.

Meteorological effects on the activity of the giant burrowing frog (Heleioporus australiacus) in south-eastern Australia

Activity of amphibians is strongly related to meteorological conditions. The threatened giant burrowing frog is rarely encountered, even when it is known to be present in an area. To improve its detectability and so improve our ability to manage the species we wanted to determine the conditions under which this species is active. Thirty-three frogs were tracked over a 2-year period, their location determined daily and activity measured as the proportion of frogs moved from the previous day. Animals were found to be active throughout the year and activity was associated with rainfall, humidity, temperature and wind strength. The results suggest that surveys for this species should be carried out after rainfall of at least 5mm, when temperatures are above 8°C, relative humidity above 60% and in still or light wind conditions.

Impact of a Chytrid-related mortality event on a population of the Green and Golden Bell Frog Litoria aurea

Chytridiomycosis is considered a key threatening process under Commonwealth legislation. Little is known of the impact of this pathogen within wild populations. The Green and Golden Bell Frog Litor...

Do young eucalypt plantations benefit bats in an intensive agricultural landscape

Context Environmental benefits of timber plantations have been a major selling point for land use change from previously cleared farmland, but data concerning the response of biodiversity are scarce. Aims We investigated the use of young (4–11 years old) timber plantations by bats in comparison with other vegetation classes in a highly cleared and productive agricultural landscape in north-west New South Wales (NSW), Australia. Methods Initially, we recorded activity in paddocks before plantation establishment, and then four to six years after establishment. We compared activity within young eucalypt plantations with surrounding paddocks and remnant woodland. We also radio-tracked four different bat species to investigate how roosting and foraging was apportioned into different habitats. Key results The ultrasonic survey of bats found that the young plantations were typically used by 7–8 species and activity averaged 87 passes per night. Activity within plantations was similar to treeless paddocks, and approximately six times less than in small remnants. The very high activity levels and feeding buzzes in small remnants was significantly related to rich, basalt soil (which was used as a proxy for invertebrate biomass) on agricultural plains. Total activity and species richness was correlated positively with the number of remnant trees on the site, but neither plantation area nor shape influenced bat activity. Plantations were not used preferentially by radio-tracked bats at night compared with their availability in the local landscape (13–14% bat use, 17% available). No bat roosts were located within the plantations. Most bat roosts were in tree hollows, which were absent in the plantations. Decorticating bark was abundant in eucalypt plantations, but only Nyctophilus geoffroyi was observed beneath bark and only in remnant trees outside of plantations. Conclusions Young eucalypt plantations have limited value for bats, and this is comparable to previous studies on more environmentally focussed plantings. Implications The value of plantations for bats would be improved by retaining remnant trees, both in the surrounding landscape and within plantations. We also recommend varying tree densities to increase the diversity of animal species using plantations.

A cost-benefit analysis of automated call recorders

Automated survey devices have the potential to improve the efficiency and extent of field surveys, but their success in doing so is rarely tested. This study examines the potential value of a simple automated call recorder for use in amphibian surveys in south-eastern Australia. We conduct a cost benefit analysis comparing automated call recorders and single site stationary auditory survey. Each technique has its own benefits in regards to data quality and collection. Overall, we found automated call recorders to be cheaper than manual surveys to achieve the same objective in our system. The use of automated call recorders should be considered in many studies and could be extended to include a range of other animal groups.