39 research outputs found

    Do state-and-transition models derived from vegetation succession also represent avian succession in restored mine pits?

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    State-and-transition models are increasingly used as a tool to inform management of post-disturbance succession and effective conservation of biodiversity in production landscapes. However, if they are to do this effectively, they need to represent faunal, as well as vegetation, succession. We assessed the congruence between vegetation and avian succession by sampling avian communities in each state of a state-and-transition model used to inform management of post-mining restoration in a production landscape in southwestern Australia. While avian communities differed significantly among states classified as on a desirable successional pathway, they did not differ between desirable and deviated states of the same post-mining age. Overall, we concluded there was poor congruence between vegetation and avian succession in this state-and-transition model. We identified four factors that likely contributed to this lack of congruence, which were that long-term monitoring of succession in restored mine pits was not used to update and improve models, states were not defined based on ecological processes and thresholds, states were not defined by criteria that were important in structuring the avian community, and states were not based on criteria that related to values in the reference community. We believe that consideration of these four factors in the development of state-and-transition models should improve their ability to accurately represent faunal, as well as vegetation, succession. Developing state-and-transition models that better incorporate patterns of faunal succession should improve the ability to manage post-disturbance succession across a range of ecosystems for biodiversity conservation

    Does habitat structure influence capture probabilities? A study of reptiles in a eucalypt forest

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    Pitfall traps are commonly used to examine differences in reptile communities among habitat types and disturbance regimes that differ in structure. However, capture rates and probabilities may be influenced by habitat structure, which invalidates comparisons of relative abundance among habitat types. To assess whether pitfall traps provide accurate reflections of density and whether habitat structure affects capture probabilities, we trapped at six sites in various jarrah-forest habitat types in south-western Australia, then intensively searched 150-m2 total-removal plots around each pitfall grid to obtain absolute densities of reptiles. Pitfall captures were significantly correlated with numbers on total-removal plots for Hemiergis initialis and Lerista distinguenda, indicating that pitfall traps provided accurate reflections of density for these species. Capture probabilities of H. initialis and L. distinguenda and all reptiles combined showed no significant correlations with any structural variables, indicating that capture probabilities were consistent across sites. We conclude that trapping provided accurate estimates of relative abundance for some species and that capture probabilities were not influenced by vegetation structure. Because many studies use trapping to estimate abundances among habitat types, we encourage researchers to investigate how vegetation structure influences capture probabilities, so that general patterns can be determined; we also suggest improvements for any future studies

    Does coarse woody debris density and volume influence the terrestrial vertebrate community in restored bauxite mines?

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    Coarse woody debris (CWD) is a critical functional and structural component of forest and woodland ecosystems, providing habitat for many species, and is an important consideration in forest and woodland restoration. CWD is very slow to develop naturally so, to accelerate the return of CWD-dependent species to restored areas, CWD is commonly returned manually. However, few studies have tested the effectiveness of such a strategy. We investigated whether the provision of CWD, heaped into 'habitat piles' of varying density (0.4-5.7pilesha-1), was effective in accelerating recolonisation by reptiles, frogs and mammals into 3-year old restored bauxite mine-pits in south-western Western Australia. Both reptile and mammal communities, and the abundances of some individual species, differed significantly between unmined and restored forest but the provision of CWD had only a weak effect in accelerating recolonisation. Acritoscincus trilineatus abundance showed a weak positive relationship with habitat pile density and both Cryptoblepharus buchananii and Christinus marmoratus, species that are very rare in restoration, were recorded adjacent to habitat piles in two and one mine-pits respectively. The weak effects of CWD in accelerating recolonisation were likely due to the differences in vegetation between unmined and restored forest, resulting in restored forests being primarily inhabited by generalist species that did not require CWD, and the highest habitat pile densities being ≀6% of log densities in unmined forest, suggesting that CWD-dependent species perceived all mine-pits as having similarly low levels of CWD, compared to unmined forest. Our results suggest that the provision of CWD in restored areas is critical to accelerate recolonisation of CWD-dependent fauna, but this will require consideration of both CWD spatial connectivity and temporal continuity. Spatial connectivity would be best achieved through CWD densities that approximate those in reference ecosystems, whereas temporal continuity will be harder to achieve, particularly in systems where CWD is slow to develop, and will require the development of innovative techniques and long-term management. However, ensuring the spatial connectivity and temporal continuity of CWD in restored areas should greatly increase their biodiversity value

    Viscoelastic properties of skin in Mov-13 and Tsk mice

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    Viscoelastic properties of skin samples were measured in three types of mice (tight skin, Tsk, control and Mov-13), that are known to differ with regard to content of type I collagen. The experimental design used uniaxial stretching and measured the creep response and the complex compliance. The creep response was measured directly. The complex compliance was determined using a Wiener-Volterra constitutive model for each sample. The models were calculated from data obtained by applying a stress input having a pseudo-Gaussian waveform, and measuring the strain response. The storage compliance of Mov-13 and control skin were similar and were greater than Tsk (p<0.001). The loss compliance of each group was significantly different (p<0.001) from each other group;, Tsk had the lowest and control had the highest loss compliance. The phase angle of the Mov-13 and Tsk were similar and were less than the controls (p<0.001). The creep response was fit with a linear viscoelastic model. None of the parameters in the creep model differed between groups. The results indicate that gene-targeted and mutant animals have soft tissue mechanical phenotypes that differ in complex ways. Caution should be exercised when using such animals as models to explore the role of specific constituents on tissue properties. (C) 2004 Elsevier Ltd. All rights reserved

    Identifying optimal solutions between competing economic and conservation land use objectives for species that require widely distributed resources

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    Across the world, wildlife must coexist with humans in modified and increasingly fragmented landscapes but balancing the competing land use objectives of economic production and conservation is challenging. Multi-objective optimisation and spatial conservation prioritisation can inform land use planning but have not yet explicitly accounted for the way species access multiple resources at different locations in a landscape. Here, we demonstrate a novel approach for conservation prioritisation that accounts for the spatial distribution of different resources as well as a species' movements. This suite of tools and models identifies Pareto-optimal solutions to competing objectives of economic production on the one hand, with conserving a species’ food, drink and shelter requirements and movement corridors on the other. We demonstrate the broader functionality of these tools using a case study with competing objectives of clearing land for mining versus conservation of a vulnerable endemic species

    The influence of time, soil moisture and exogenous factors on the survival potential of oospores and chlamydospores of Phytophthora cinnamomi

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    The mode of persistence of Phytophthora cinnamomi, a highly aggressive soil‐ and water‐borne pathogen, remains unclear. This study investigated the survival of viable oospores and chlamydospores of P. cinnamomi when present as free propagules in untreated soil, or in soil subject to four exogenous treatments: smoke water, fish emulsion and two fungicides (ridomil and furalaxyl). The exogenous treatments were applied under moist and dry soil conditions. Spore viability was determined by the thiazolyl blue tetrazolium bromide (MTT) staining technique, with a qPCR assay used to compare general patterns of decline. Over 96% of oospores lost viability over a period of 48 weeks irrespective of soil moisture conditions. The mean percentage viability for oospores decreased from 91% at time zero to 72, 35, 20 and 1% after 6, 12, 24 and 48 weeks, respectively. Reduction in viability of chlamydospores was more rapid than oospores, with viability declining from 92% to zero after 12 weeks. There was no significant difference between untreated soil and the exogenous treatments. The RNA‐based qPCR assay indicated a strong presence of viable oospores of P. cinnamomi up to week 12 for moist soil and week 3 for dry soil, but thereafter failed to detect RNA even though viable oospores could be detected by MTT staining. Based on the MTT staining, this study indicated that viability of P. cinnamomi oospores may be entirely lost within 1 year and that of chlamydospores within 3 months for the soil type tested. Therefore, oospores and chlamydospores when existing as free propagules in soil appear unlikely to be involved in the long‐term survival of P. cinnamomi

    A funnel trap for capture of small arboreal reptiles

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    Small arboreal reptiles can be difficult to capture, except in traps, and the physical trap characteristics, drift-fence and bait are critical factors that can influence the efficacy of any trap. We conducted experiments on marbled geckoes (Christinus marmoratus, Gekkonidae) and wall skinks (Cryptoblepharus plagiocephalus, Scincidae) that examined bait preferences, attractiveness of different visual and acoustic cues and efficacy of different drift-fence materials to develop a trap for small arboreal reptiles. The experiments showed that both marbled geckos and wall skinks preferred crickets as bait, that wall skinks avoided darkness/cover and that both species had difficulty climbing flashing material covered in oil. This led us to develop an arboreal trap that was made from transparent material, used crickets as bait and had drift-fences constructed from flashing material. When used in the field, the final trap design was effective in capturing arboreal reptile

    Beyond species richness and community composition: Using plant functional diversity to measure restoration success in jarrah forest

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    Aim The importance of restoring ecosystem functions to native systems that have been degraded, damaged or destroyed is increasingly recognised. Yet few studies have measured the effect of restoration efforts on ecosystem functioning or the functional diversity (FD) that underpins it. Here we assessed change in FD of restored assemblages one to 25 years after the onset of post-mine restoration. Location Northern Jarrah (Eucalyptus marginata Donn ex Sm.) Forest bioregion of southwestern Australia. Methods Functional richness, evenness, divergence and dispersion were derived from five plant functional traits relevant to community reassembly. Effects of three explanatory variables (i.e. age, year restoration was initiated, and time since fire) on six response variables (i.e. four FD indices, species richness, and compositional similarity to nearby reference forest) were analysed using linear mixed models for a data set with repeated measures of plots through time (n = 810 plots), and linear models for a subset of one-time measures of different aged assemblages (i.e. space-for-time approach; n = 490 plots). Results Functional evenness and functional dispersion increased with age, while functional divergence and functional richness decreased with age. Functional dispersion increased with time since fire, while functional richness decreased with time since fire. Species richness decreased with age, but at 25 years, species richness was comparable to that observed in reference forest. In contrast, similarity showed no relationship with age of restored forest, and at 25 years, similarity of restored forest to reference was low compared with similarity of reference forest to itself. Three of four FD indices had not reached those of reference jarrah forest 25 years after restoration had been initiated. Conclusions Reassembly of FD suggests importance of environmental filtering and high functional redundancy. A longer time frame may be needed to assess FD of restored assemblages, and in the meantime, species richness is not an adequate surrogate of FD

    How many mature microhabitats does a slow-recolonising reptile require? Implications for restoration of bauxite minesites in south-western Australia

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    If we are to accelerate the recolonisation of restored areas by slow-recolonising species, we must provide suitable microhabitats at appropriate densities. Previous research in south-western Australia has shown that Napoleon’s skink (Egernia napoleonis) rarely recolonises restored areas. We trapped Napoleon’s skink in restoration and unmined forest to confirm the species was late successional. We also radio-tracked six skinks in unmined forest, to determine types and characteristics of used microhabitats, and estimated home ranges to determine required microhabitat densities, with the aim of accelerating skink recolonisation of restored areas. All tracked skinks used logs and hollow-bearing trees. Used logs were larger, and used trees were larger and taller than random samples, probably because large logs and trees were more likely to contain cracks and hollows that provide a refuge from predators. Extrapolations from home-range estimates indicated that a minimum of four logs ha–1 are required in restored areas to facilitate recolonisation by skinks, with skink densities likely to increase with log densities. Our study demonstrated that not all fauna will naturally recolonise restored areas and management of these areas is required to provide suitable habitat for late-successional species. Our approach could potentially be applied to other ecosystems or species
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