School of Ecosystem and Forest Sciences - Research Publications
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ItemFire effects on pollination in a sexually deceptive orchid(CSIRO PUBLISHING, 2016-01-01)Research into the effectiveness of prescribed fire in managing pollination has only recently begun. The effects of fire on pollination have not been explored in sexually deceptive systems. Further, the potential for multiple effects operating at different spatial scales has not been explored in any pollination system despite multiscale effects on pollination observed in agricultural landscapes. We observed the frequency of pollinator visitation to flowers of sexually deceptive Caladenia tentaculata and related it to the post-fire age class of the vegetation at local and landscape scales. We also related the number of the pollinator’s putative larval hosts (scarab beetles) captured at these sites to age class. At the local scale (i.e. the sample location), visitation was highest in recently burnt sites. At the landscape scale, positive associations were observed between (1) putative pollinator hosts and vegetation burnt 36–50 years ago, and (2) pollinator visitation and vegetation burnt ≥50 years ago. Local- and landscape-scale effects on visitation were synergistic, such that visitation was greatest when fire age was heterogeneous within pollinator foraging range.
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ItemHabitat characteristics of a threatened arboreal marsupial and its resource use in a degraded landscape: the brush-tailed phascogale (Phascogale tapoatafa tapoatafa) in central Victoria, Australia(CSIRO PUBLISHING, 2017-06-01)Context Habitat loss and degradation has contributed significantly to the decline of many species worldwide. To address this loss, we first require a comprehensive understanding of habitat requirements and resource-use patterns of the species under threat. Aims The study aimed to quantify variation in the habitat of a species threatened by habitat loss and degradation, the brush-tailed phascogale (Phascogale tapoatafa tapoatafa), by measuring several physical characteristics of trees and ground cover, as well as to determine potential foraging resource preferences using abundance data from a long-term monitoring study. Methods Phascogale monitoring surveys were conducted over a 13-year period from 2000 to 2012. Habitat variables characterising tree communities, ground cover and coarse woody debris were used to develop explanatory models of phascogale abundance at the site scale. Tree species preference by foraging phascogales was evaluated by comparing usage (trees on which they were captured) and availability. Key results The highest overall animal abundance was at sites characterised by associations of red stringybark, red box, grey box and broad-leaved and narrow-leaved peppermints. At these sites, red stringybark and grey box trees were of small diameter and tended to have small hollows. These sites also had low average tree height, low grass and/or herb and shrub cover and low volumes of coarse woody debris. From a resource-use perspective, phascogales foraged preferentially on certain species of Eucalyptus. Conclusions Our study suggests that phascogale abundance is highly spatially and temporally variable, most likely as a response to heterogeneity in habitat and foraging resources operating at a range of spatial scales. Implications This study has provided new information concerning spatial patterns of phascogale abundance and resource use within a forested area in central Victoria that has been subjected to multiple disturbances. Currently, the composition and age structure of tree communities and ground habitats are a response to severe disturbance due to past mining and harvesting activities. Successful conservation of this threatened species could be enhanced through active management of this forest to maintain the ongoing supply of nesting hollows and foraging resources.
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ItemUnderstanding the effects of fire on invertebrates in Australian temperate and sub-tropical forests: The value of long-term experiments(Royal Zoological Society of New South Wales, 2018-01-01)Fire is a common feature of Australian forests and prescribed burning is a routine management strategy, often utilised to mitigate the effects of wildfire. However, the impacts of fire on terrestrial invertebrates are poorly understood. Here we provide an overview of continuing long-term fire studies in temperate and sub-tropical forest ecosystems, with a focus on terrestrial invertebrates Longitudinal fire study sites exist in southern Queensland, New South Wales, Victoria, Western Australia and Tasmania. Most studies have focussed on fire frequency and have identified certain taxa or taxonomic groups that prefer either habitat associated with long unburnt areas, habitat associated with more frequently burnt areas or those that show no response to varied fire frequency.The limited number of studies investigating fire season report similar findings, but there are few studies that have focussed on other components of the fire regime. Long-term experiments are important when studying the effects of various fire regimes on invertebrate assemblages as responses often take time to be expressed, and may follow changes in habitat availability associated with interactions between components of the fire regime. We recommend that ecological studies continue to utilise long-term study sites through monitoring programs to improve our understanding of how invertebrate taxa respond to fire regimes; and to better identify the important role of invertebrate groups in ecosystem functioning (e.g. for nutrient cycling, pollination).
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ItemFire planning for multispecies conservation: Integrating growth stage and fire severity(Elsevier, 2018-05-01)Setting suitable conservation targets is an important part of ecological fire planning. Growth-stage optimisation (GSO) determines the relative proportions of post-fire growth stages (categorical representations of time since fire) that maximise species diversity, and is a useful method for determining such targets. Optimisation methods can accommodate various predictor variables, but to date have only been applied using post-fire growth stages as the primary landscape variable. However, other aspects of fire regimes such as severity may influence species diversity but have not yet been considered in determining conservation targets in fire planning. Here we use a space-for-time substitution to address two objectives, 1. To determine the effects of growth stage and fire severity on plant and vertebrate species’ occurrence, and 2. To determine the optimal mix of growth stages and fire severities for sustaining the diversity of these groups. We used the tall wet forests of southeast Australia as the focal system because fire severity is expected to create distinct successional pathways and influence species’ responses. We found that growth stage predicted the occurrence of many species, and severity of the most recent fire was an important factor over and above growth stage for a small subset of species. The optimal distribution of growth stages for both plants and animals included a substantial proportion of young forest, however when fire severity was considered, areas burned at low severity were most important in driving the diversity of both groups. Growth stage is a good surrogate for developing conservation targets in tall wet forests, however growth stage alone does not capture the full range of species’ fire responses. More complex versions of growth stage optimisation that accommodate multiple fire-regime variables need to be explored to yield ecologically meaningful conservation goals.
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ItemHabitat use at fire edges: Does animal activity follow temporal patterns of habitat change?(Elsevier, 2019-11-01)Edges are ecologically important environmental features that have been well researched in agricultural and urban landscapes. However, little work has been conducted in flammable ecosystems where spatially and temporally dynamic fire edges are expected to influence animal activity patterns, particularly for animals reliant on vegetation for cover, foraging or nesting. We quantified the response of ground-dwelling mammals to fire edges and sought to determine whether animal activity mirrored temporal changes in regenerating understorey vegetation. We used a space-for-time substitution sampling design and selected a series of 26 treatment sites burnt by prescribed fire, where time since fire ranged from 0 to 7 years. Ten long-unburnt sites acted as controls. At each treatment site we identified a burnt/unburnt edge and used camera traps and Elliott traps to survey ground-dwelling mammals on either side. Habitat structure was measured at all 36 sites. We used general and generalised linear mixed models to determine the response of both habitat and animals to time since fire on both burnt and unburnt sides of edges. In addition, we used a resource selection index to assess the congruence between changes in understorey complexity and animal activity identified in the first set of analyses. On the unburnt side of the edge understorey complexity remained constant over time. On the burnt side understorey complexity followed a hump-shaped trend, peaking at 3 years post-fire where it exceeded the level of complexity on the unburnt edge. Larger animals with general resource requirements were more active at burnt compared to unburnt edges immediately after fire, but similarly active on both sides of fire edges from three years post-fire. Despite some activity on the burnt side of edges immediately after fire, small mammals were generally less active on burnt edges compared to unburnt edges for up to three years. Native species’ activity did not follow patterns of temporal change in structurally complex understorey vegetation. For all species, selection was strongest at recently burnt edges with little vegetation and substantially lower at 3–7 year old regenerating edges where understorey complexity was higher. In general, patterns of selection on the unburnt side of edges were similar over time. Our findings suggest that vegetation change on the burnt side of fire edges may not be a good predictor of native mammal use. Foxes and cats, exotic predators in our system, were also using the burnt edge more than expected immediately after fire. Immediate post-fire predation may be higher at fire edges than elsewhere, and recently burnt edge zones could be suitable locations for integrated predator and fire management.
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ItemSurvey design for precise fire management conservation targets(WILEY, 2018-01-01)Common goals of ecological fire management are to sustain biodiversity and minimize extinction risk. A novel approach to achieving these goals determines the relative proportions of vegetation growth stages (equivalent to successional stages, which are categorical representations of time since fire) that maximize a biodiversity index. The method combines data describing species abundances in each growth stage with numerical optimization to define an optimal growth-stage structure that provides a conservation-based operational target for managers. However, conservation targets derived from growth-stage optimization are likely to depend critically on choices regarding input data. There is growing interest in the use of growth-stage optimization as a basis for fire management, thus understanding of how input data influence the outputs is crucial. Simulated data sets provide a flexible platform for systematically varying aspects of survey design and species inclusions. We used artificial data with known properties, and a case-study data set from southeastern Australia, to examine the influence of (1) survey design (total number of sites and their distribution among growth stages) and (2) species inclusions (total number of species and their level of specialization) on the precision of conservation targets. Based on our findings, we recommend that survey designs for precise estimates would ideally involve at least 80 sites, and include at least 80 species. Greater numbers of sites and species will yield increasingly reliable results, but fewer might be sufficient in some circumstances. An even distribution of sites among growth stages was less important than the total number of sites, and omission of species is unlikely to have a major influence on results as long as several species specialize on each growth stage. We highlight the importance of examining the responses of individual species to growth stage before feeding survey data into the growth-stage optimization black box, and advocate use of a resampling procedure to determine the precision of results. Collectively, our findings form a reproducible guide to designing ecological surveys that yield precise conservation targets through growth-stage optimization, and ultimately help sustain biodiversity in fire-prone systems.
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ItemFire, food and sexual deception in the neighbourhood of some Australian orchids(WILEY, 2017-06-01)The effective use of prescribed fire in biodiversity conservation is currently inhibited by a limited understanding of fire effects on ecosystem processes such as pollination. Orchids inhabiting fireâ prone landscapes are likely to be particularly sensitive because they often exhibit highly specialized pollination systems and provide no reward to pollinators, making them dependent on coâ flowering heterospecifics to attract and support pollinators. We investigated the hypothesis that fireâ driven changes in the local abundance of rewarding heterospecific flowers influence pollination in two rewardless Australian orchid species, Diuris maculata sensu lato and Caladenia tentaculata. Diuris maculata s.l. is thought to achieve pollination by mimicking papilionoid Fabaceae flowers. Caladenia tentaculata attracts male thynnine wasps through sexual deceit, and these wasps forage on the openâ access flowers of other taxa. We used a spaceâ forâ time substitution design with sites in different stages of postâ fire succession where we recorded capsule set in D. maculata s.l., pollinator visitation to C. tentaculata, the floral abundance of rewarding heterospecifics and abiotic conditions. Many rewarding taxa responded to fire age, but there was only weak evidence that capsule set in D. maculata s.l. was positively related to the local floral abundance of rewarding species. There was evidence of an overriding effect of rainfall on capsule set that may have obscured effects of the floral community. Visitation to C. tentaculata was not positively associated with any rewarding heterospecifics, and was negatively associated with rewarding Burchardia umbellata. Our preliminary findings highlight the need to account for multiple factors when trying to detect fire effects on pollination.
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ItemContrasting responses of small mammals to fire and topographic refugia(WILEY, 2016-06-01)
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ItemEffects of fire on pollinators and pollination(Wiley, 2017-02-01)Summary 1. Increased incidence of landscape fire and pollinator declines with co‐extinctions of dependent plant species are both globally significant. Fire can alter species distributions, but its effects on plant–pollinator interactions are poorly understood so its present and future role in coupled plant–pollinator declines cannot be assessed. 2. We develop a conceptual model of fire effects on plant–pollinator interactions. We review the empirical literature in the context of this model to identify important knowledge gaps regarding the processes underlying these effects and the phenotypic traits of flowering plants and pollinators mediating these effects. Fire generates, and plant–pollinator interactions respond to, heterogeneity at multiple spatial scales. There is evidence of local‐scale fire effects on these interactions, but landscape‐scale effects are poorly understood. Nest location and floral resource utilization primarily mediate pollinator survival during and after fire. Voltinism and mobility traits are potentially important, but poorly studied. Plant traits mediating flowering responses to fire include growth form, phenology and potentially bud location, seasonal changes in bud exposure and response to bud damage. 3. Synthesis and applications. We suggest management actions and an agenda for future research to fill knowledge gaps currently inhibiting predictions of fire effects on plant–pollinator interactions. Fire regimes promoting floral diversity at local scales provide a surrogate means of managing pollinators and pollination while empirical research continues. Above‐ground nesting, univoltine pollinators may be particularly vulnerable under expected fire regime changes. Improved knowledge of traits mediating the exploitation of landscape heterogeneity could be used to enhance the persistence of these species. Ultimately, our conceptual framework could be used as a basis for understanding fire effects on aggregate network properties to inform fire management strategies buffering plant–pollinator networks against secondary species extinctions.
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ItemThe response of cerambycid beetles (Coleoptera: Cerambycidae) to long-term fire frequency regimes in subtropical eucalypt forest(WILEY, 2019-06-01)Fire has a varied influence on plant and animal species through direct (e.g. fire‐induced mortality) and indirect (e.g. modification of habitat) effects. Our understanding of the influence of fire regime on invertebrates and their response to fire‐induced modifications to habitat is poor. We aimed to determine the response of a beetle family (Coleoptera: Cerambycidae) to varying fire treatments and hypothesised that the abundance of cerambycid beetles is influenced by fire frequency due to modifications in habitat associated with the fire treatments. Arthropods were sampled across 3 months in annually and triennially burnt areas (treatments starting in 1952 and 1973 respectively), an area unburnt since 1946, and a former unburnt treatment, burnt by wildfire in 2006. Eleven different cerambycid taxa were collected using flight intercept panel traps, dominated by three species (Ipomoria tillides, Adrium sp. and Bethelium signiferum) which made up 99% of individuals collected. Over the sampling period the long unburnt treatment had significantly lower species richness than the triennial and wildfire treatments. Cerambycid abundance was significantly higher in the triennially burnt treatment than in all other fire treatments. Ipomoria tillides was more abundant in both frequently burnt treatments, Adrium sp. was more common in triennially burnt areas, whereas B. signiferum, was more common in the wildfire affected treatment. Some, but not all, cerambycid beetles were more common in areas with a more open understorey (i.e. resulting from frequent burning), and lower tree basal area, as this likely influences their ability to fly easily between food sources. Cerambycid abundance was positively related to the volume of coarse woody debris and healthy tree crowns. Cerambycid beetles were clearly influenced by historic fire regime, suggesting that changes in fire regime can potentially have a profound influence on arthropod assemblages, and subsequent influences on ecosystem processes, which are currently poorly understood.