- Neilan, Wendy, Barton, Philip, McAlpine, Clive, Wood, Jeffrey, Lindenmayer, David
- Authors: Neilan, Wendy , Barton, Philip , McAlpine, Clive , Wood, Jeffrey , Lindenmayer, David
- Date: 2019
- Type: Text , Journal article
- Relation: Ecography Vol. 42, no. 1 (2019), p. 173-186
- Full Text: false
- Reviewed:
- Description: Habitat loss and fragmentation are key processes causing biodiversity loss in human-modified landscapes. Knowledge of these processes has largely been derived from measuring biodiversity at the scale of ‘within-habitat’ fragments with the surrounding landscape considered as matrix. Yet, the loss of variation in species assemblages ‘among’ habitat fragments (landscape-scale) may be as important a driver of biodiversity loss as the loss of diversity ‘within’ habitat fragments (local-scale). We tested the hypothesis that heterogeneity in vegetation cover is important for maintaining alpha and beta diversity in human-modified landscapes. We surveyed bird assemblages in eighty 300-m-long transects nested within twenty 1-km 2 vegetation ‘mosaics’, with mosaics assigned to four categories defined by the cover extent and configuration of native eucalypt forest and exotic pine plantation. We examined bird assemblages at two spatial scales: 1) within and among transects, and 2) within and among mosaics. Alpha diversity was the mean species diversity within-transects or within-mosaics and beta diversity quantified the effective number of compositionally distinct transects or mosaics. We found that within-transect alpha diversity was highest in vegetation mosaics defined by continuous eucalypt forest, lowest in mosaics of continuous pine plantation, and at intermediate levels in mosaics containing eucalypt patches in a pine matrix. We found that eucalypt mosaics had lower beta diversity than other mosaic types when ignoring relative abundances, but had similar or higher beta diversity when weighting with species abundances. Mosaics containing both pine and eucalypt forest differed in their bird compositional variation among transects, despite sharing a similar suite of species. This configuration effect at the mosaic scale reflected differences in vegetation composition among transects. Maintaining heterogeneity in vegetation cover could help to maintain variation among bird assemblages across landscapes, thus partially offsetting local-scale diversity losses due to fragmentation. Critical to this is the retention of remnant native vegetation. © 2018 The Authors
Species co-occurrence networks show reptile community reorganization under agricultural transformation
- Kay, Geoffrey, Tulloch, Ayesha, Barton, Philip, Cunningham, Saul, Driscoll, Don, Lindenmayer, David
- Authors: Kay, Geoffrey , Tulloch, Ayesha , Barton, Philip , Cunningham, Saul , Driscoll, Don , Lindenmayer, David
- Date: 2018
- Type: Text , Journal article
- Relation: Ecography Vol. 41, no. 1 (2018), p. 113-125
- Full Text:
- Reviewed:
- Description: Agricultural transformation represents one of the greatest threats to biodiversity, causing degradation and loss of habitat, leading to changes in the richness and composition of communities. These changes in richness and composition may, in turn, lead to altered species co-occurrence, but our knowledge of this remains limited. We used a novel co-occurrence network approach to examine the impact of agricultural transformation on reptile community structure within two large (> 172 000 km2; 224 sites) agricultural regions in southeastern Australia. We contrasted assemblages from sites surrounded by intact and modified landscapes and tested four key hypotheses that agricultural transformation leads to (H1) declines in species richness, (H2) altered assemblages, (H3) declines in overall co-occurrence, and (H4) complex restructuring of pairwise associations. We found that modified landscapes differed in composition but not richness compared with intact sites. Modified landscapes were also characterized by differences in co-occurrence network structure; with species sharing fewer sites with each other (reduced co-occurrence connectance), fewer highly-connected species (truncation of the frequency distribution of co-occurrence degree) and increased modularity of co-occurrence networks. Critically, overall loss of co-occurrence was underpinned by complex changes to the number and distribution of pair-wise co-occurrence links, with 41–44% of species also gaining associations with other species. Change in co-occurrence was not correlated with changes in occupancy, nor by functional trait membership, allowing a novel classification of species susceptibility to agricultural transformation. Our study reveals the value of using co-occurrence analysis to uncover impacts of agricultural transformation that may be masked in conventional studies of species richness and community composition. © 2017 The Authors
- Authors: Kay, Geoffrey , Tulloch, Ayesha , Barton, Philip , Cunningham, Saul , Driscoll, Don , Lindenmayer, David
- Date: 2018
- Type: Text , Journal article
- Relation: Ecography Vol. 41, no. 1 (2018), p. 113-125
- Full Text:
- Reviewed:
- Description: Agricultural transformation represents one of the greatest threats to biodiversity, causing degradation and loss of habitat, leading to changes in the richness and composition of communities. These changes in richness and composition may, in turn, lead to altered species co-occurrence, but our knowledge of this remains limited. We used a novel co-occurrence network approach to examine the impact of agricultural transformation on reptile community structure within two large (> 172 000 km2; 224 sites) agricultural regions in southeastern Australia. We contrasted assemblages from sites surrounded by intact and modified landscapes and tested four key hypotheses that agricultural transformation leads to (H1) declines in species richness, (H2) altered assemblages, (H3) declines in overall co-occurrence, and (H4) complex restructuring of pairwise associations. We found that modified landscapes differed in composition but not richness compared with intact sites. Modified landscapes were also characterized by differences in co-occurrence network structure; with species sharing fewer sites with each other (reduced co-occurrence connectance), fewer highly-connected species (truncation of the frequency distribution of co-occurrence degree) and increased modularity of co-occurrence networks. Critically, overall loss of co-occurrence was underpinned by complex changes to the number and distribution of pair-wise co-occurrence links, with 41–44% of species also gaining associations with other species. Change in co-occurrence was not correlated with changes in occupancy, nor by functional trait membership, allowing a novel classification of species susceptibility to agricultural transformation. Our study reveals the value of using co-occurrence analysis to uncover impacts of agricultural transformation that may be masked in conventional studies of species richness and community composition. © 2017 The Authors
Optimal taxonomic groups for biodiversity assessment: a meta-analytic approach
- Westgate, Martin, Tulloch, Ayesha, Barton, Philip, Pierson, Jennifer, Lindenmayer, David
- Authors: Westgate, Martin , Tulloch, Ayesha , Barton, Philip , Pierson, Jennifer , Lindenmayer, David
- Date: 2017
- Type: Text , Journal article
- Relation: Ecography Vol. 40, no. 4 (2017), p. 539-548
- Full Text:
- Reviewed:
- Description: A fundamental decision in biodiversity assessment is the selection of one or more study taxa, a choice that is often made using qualitative criteria such as historical precedent, ease of detection, or available technical or taxonomic expertise. A more robust approach would involve selecting taxa based on the a priori expectation that they will provide the best possible information on unmeasured groups, but data to inform such hypotheses are often lacking. Using a global meta-analysis, we quantified the proportion of variability that each of 12 taxonomic groups (at the Order level or above) explained in the richness or composition of other taxa. We then applied optimization to matrices of pairwise congruency to identify the best set of complementary surrogate groups. We found that no single taxon was an optimal surrogate for both the richness and composition of unmeasured taxa if we used simple methods to aggregate congruence data between studies. In contrast, statistical methods that accounted for well-known drivers of cross-taxon congruence (spatial extent, grain size, and latitude) lead to the prioritization of similar surrogates for both species richness and composition. Advanced statistical methods were also more effective at describing known ecological relationships between taxa than simple methods, and show that congruence is typically highest between taxonomically and functionally dissimilar taxa. Birds and vascular plants were most frequently selected by our algorithm as surrogates for other taxonomic groups, but the extent to which any one taxon was the ‘optimal’ choice of surrogate for other biodiversity was highly context-dependent. In the absence of other information – such as in data-poor areas of the globe, and under limited budgets for monitoring or assessment – ecologists can use our results to assess which taxa are most likely to reflect the distribution of the richness or composition of ‘total’ biodiversity. © 2016 The Authors
- Authors: Westgate, Martin , Tulloch, Ayesha , Barton, Philip , Pierson, Jennifer , Lindenmayer, David
- Date: 2017
- Type: Text , Journal article
- Relation: Ecography Vol. 40, no. 4 (2017), p. 539-548
- Full Text:
- Reviewed:
- Description: A fundamental decision in biodiversity assessment is the selection of one or more study taxa, a choice that is often made using qualitative criteria such as historical precedent, ease of detection, or available technical or taxonomic expertise. A more robust approach would involve selecting taxa based on the a priori expectation that they will provide the best possible information on unmeasured groups, but data to inform such hypotheses are often lacking. Using a global meta-analysis, we quantified the proportion of variability that each of 12 taxonomic groups (at the Order level or above) explained in the richness or composition of other taxa. We then applied optimization to matrices of pairwise congruency to identify the best set of complementary surrogate groups. We found that no single taxon was an optimal surrogate for both the richness and composition of unmeasured taxa if we used simple methods to aggregate congruence data between studies. In contrast, statistical methods that accounted for well-known drivers of cross-taxon congruence (spatial extent, grain size, and latitude) lead to the prioritization of similar surrogates for both species richness and composition. Advanced statistical methods were also more effective at describing known ecological relationships between taxa than simple methods, and show that congruence is typically highest between taxonomically and functionally dissimilar taxa. Birds and vascular plants were most frequently selected by our algorithm as surrogates for other taxonomic groups, but the extent to which any one taxon was the ‘optimal’ choice of surrogate for other biodiversity was highly context-dependent. In the absence of other information – such as in data-poor areas of the globe, and under limited budgets for monitoring or assessment – ecologists can use our results to assess which taxa are most likely to reflect the distribution of the richness or composition of ‘total’ biodiversity. © 2016 The Authors
Remnant vegetation, plantings and fences are beneficial for reptiles in agricultural landscapes
- Pulsford, Stephanie, Driscoll, Don, Barton, Philip, Lindenmayer, David
- Authors: Pulsford, Stephanie , Driscoll, Don , Barton, Philip , Lindenmayer, David
- Date: 2017
- Type: Text , Journal article
- Relation: Journal of Applied Ecology Vol. 54, no. 6 (2017), p. 1710-1719
- Full Text:
- Reviewed:
- Description: Managing agricultural landscapes for biodiversity conservation is increasingly difficult as land use is modified or intensified for production. Finding ways to mitigate the negative effects of agriculture on biodiversity is therefore critical. We asked the question: How do remnant patches, paddock types and grazing regimes influence reptile assemblages in a grazing landscape? At 12 sites, we surveyed reptiles and environmental covariates in remnant woodland patches and in four paddock types: (i) grazed pasture, (ii) linear plantings, (iii) coarse woody debris (CWD) added to grazed pasture and (iv) fences between grazed pasture. Each site was either continuously or rotationally grazed. Remnant vegetation and other vegetation attributes such as tree cover and leaf litter greatly influenced reptiles. We recorded higher reptile abundance and species richness in areas with more tree cover and leaf litter. For rare species (captured in ≤4 sites <70 captures), there were 5·7 more animals and 2·6 more species in sites with 50% woody cover within 3 km compared to 5% woody cover. The abundance and richness of rare species, and one common species differed between paddock types and were higher in linear plantings and fence transects compared to CWD and pasture transects. Synthesis and applications. Grazed paddocks, particularly those with key features such as fences and plantings can provide habitat for reptiles. This suggests that discrete differentiation between patch and matrix does not apply for reptiles in these systems. Management to promote reptile conservation in agricultural landscapes should involve protecting existing remnant vegetation, regardless of amount; and promote key habitat features of trees, leaf litter and shrubs. Establishing plantings and fences is important as they support high numbers of less common reptiles and may facilitate reptiles to move through and use greater amounts of the landscape. © 2017 The Authors. Journal of Applied Ecology © 2017 British Ecological Society
- Authors: Pulsford, Stephanie , Driscoll, Don , Barton, Philip , Lindenmayer, David
- Date: 2017
- Type: Text , Journal article
- Relation: Journal of Applied Ecology Vol. 54, no. 6 (2017), p. 1710-1719
- Full Text:
- Reviewed:
- Description: Managing agricultural landscapes for biodiversity conservation is increasingly difficult as land use is modified or intensified for production. Finding ways to mitigate the negative effects of agriculture on biodiversity is therefore critical. We asked the question: How do remnant patches, paddock types and grazing regimes influence reptile assemblages in a grazing landscape? At 12 sites, we surveyed reptiles and environmental covariates in remnant woodland patches and in four paddock types: (i) grazed pasture, (ii) linear plantings, (iii) coarse woody debris (CWD) added to grazed pasture and (iv) fences between grazed pasture. Each site was either continuously or rotationally grazed. Remnant vegetation and other vegetation attributes such as tree cover and leaf litter greatly influenced reptiles. We recorded higher reptile abundance and species richness in areas with more tree cover and leaf litter. For rare species (captured in ≤4 sites <70 captures), there were 5·7 more animals and 2·6 more species in sites with 50% woody cover within 3 km compared to 5% woody cover. The abundance and richness of rare species, and one common species differed between paddock types and were higher in linear plantings and fence transects compared to CWD and pasture transects. Synthesis and applications. Grazed paddocks, particularly those with key features such as fences and plantings can provide habitat for reptiles. This suggests that discrete differentiation between patch and matrix does not apply for reptiles in these systems. Management to promote reptile conservation in agricultural landscapes should involve protecting existing remnant vegetation, regardless of amount; and promote key habitat features of trees, leaf litter and shrubs. Establishing plantings and fences is important as they support high numbers of less common reptiles and may facilitate reptiles to move through and use greater amounts of the landscape. © 2017 The Authors. Journal of Applied Ecology © 2017 British Ecological Society
Herbivory and fire interact to affect forest understory habitat, but not its use by small vertebrates
- Foster, Claire, Barton, Philip, Sato, C. F., Wood, J. T., Macgregor, C. I., Lindenmayer, David
- Authors: Foster, Claire , Barton, Philip , Sato, C. F. , Wood, J. T. , Macgregor, C. I. , Lindenmayer, David
- Date: 2016
- Type: Text , Journal article
- Relation: Animal Conservation Vol. 19, no. 1 (2016), p. 15-25
- Full Text:
- Reviewed:
- Description: Herbivory and fire are two disturbances that often co-occur, but studies of their interactive effects are rare outside of grassland ecosystems. We experimentally tested the interactive effects of prescribed fire and macropod herbivory on forest understory vegetation and its vertebrate fauna. Fire and herbivory interacted synergistically to affect forest understory vegetation, with palatable plants showing poor post-fire recovery in unfenced sites compared with herbivore exclusion sites. Despite this strong interactive effect on vegetation, small vertebrates responded to the individual, and not the interactive effects of disturbance. The native insectivorous mammal Antechinus stuartii was more frequently encountered on large herbivore exclusion sites, as was the introduced European rabbit. In contrast, the small skink Lampropholis delicata was more common on sites with high densities of large herbivores. Skinks, snakes and European rabbits were also more active on burnt than unburnt sites. Our results suggest that it may be necessary to manage the macropod herbivore population after fire to prevent the decline of palatable plants, and maintain the dense habitat required by some small mammals. However, as the invasive rabbit was most active in macropod-free sites after fire, any management must include control of both types of herbivores. A mix of understory densities may also need to be maintained to ensure the persistence of species preferring more open habitats. Our study demonstrates that interactive effects of disturbance on vegetation communities may not lead to predictable effects on animals, and highlights the importance of considering both multiple stressors, and multiple species, in the management of disturbance regimes. © 2016 The Zoological Society of London.
- Authors: Foster, Claire , Barton, Philip , Sato, C. F. , Wood, J. T. , Macgregor, C. I. , Lindenmayer, David
- Date: 2016
- Type: Text , Journal article
- Relation: Animal Conservation Vol. 19, no. 1 (2016), p. 15-25
- Full Text:
- Reviewed:
- Description: Herbivory and fire are two disturbances that often co-occur, but studies of their interactive effects are rare outside of grassland ecosystems. We experimentally tested the interactive effects of prescribed fire and macropod herbivory on forest understory vegetation and its vertebrate fauna. Fire and herbivory interacted synergistically to affect forest understory vegetation, with palatable plants showing poor post-fire recovery in unfenced sites compared with herbivore exclusion sites. Despite this strong interactive effect on vegetation, small vertebrates responded to the individual, and not the interactive effects of disturbance. The native insectivorous mammal Antechinus stuartii was more frequently encountered on large herbivore exclusion sites, as was the introduced European rabbit. In contrast, the small skink Lampropholis delicata was more common on sites with high densities of large herbivores. Skinks, snakes and European rabbits were also more active on burnt than unburnt sites. Our results suggest that it may be necessary to manage the macropod herbivore population after fire to prevent the decline of palatable plants, and maintain the dense habitat required by some small mammals. However, as the invasive rabbit was most active in macropod-free sites after fire, any management must include control of both types of herbivores. A mix of understory densities may also need to be maintained to ensure the persistence of species preferring more open habitats. Our study demonstrates that interactive effects of disturbance on vegetation communities may not lead to predictable effects on animals, and highlights the importance of considering both multiple stressors, and multiple species, in the management of disturbance regimes. © 2016 The Zoological Society of London.
Integrating theory into disturbance interaction experiments to better inform ecosystem management
- Foster, Claire, Sato, Chloe, Lindenmayer, David, Barton, Philip
- Authors: Foster, Claire , Sato, Chloe , Lindenmayer, David , Barton, Philip
- Date: 2016
- Type: Text , Journal article
- Relation: Global Change Biology Vol. 22, no. 4 (2016), p. 1325-1335
- Full Text:
- Reviewed:
- Description: Managing multiple, interacting disturbances is a key challenge to biodiversity conservation, and one that will only increase as global change drivers continue to alter disturbance regimes. Theoretical studies have highlighted the importance of a mechanistic understanding of stressor interactions for improving the prediction and management of interactive effects. However, many conservation studies are not designed or interpreted in the context of theory and instead focus on case-specific management questions. This is a problem as it means that few studies test the relationships highlighted in theoretical models as being important for ecological management. We explore the extent of this problem among studies of interacting disturbances by reviewing recent experimental studies of the interaction between fire and grazing in terrestrial ecosystems. Interactions between fire and grazing can occur via a number of pathways; one disturbance can modify the other's likelihood, intensity or spatial distribution, or one disturbance can alter the other's impacts on individual organisms. The strength of such interactions will vary depending on disturbance attributes (e.g. size or intensity), and this variation is likely to be nonlinear. We show that few experiments testing fire-grazing interactions are able to identify the mechanistic pathway driving an observed interaction, and most are unable to detect nonlinear effects. We demonstrate how these limitations compromise the ability of experimental studies to effectively inform ecological management. We propose a series of adjustments to the design of disturbance interaction experiments that would enable tests of key theoretical pathways and provide the deeper ecological understanding necessary for effective management. Such considerations are relevant to studies of a broad range of ecological interactions and are critical to informing the management of disturbance regimes in the context of accelerating global change. © 2016 John Wiley & Sons Ltd.
- Authors: Foster, Claire , Sato, Chloe , Lindenmayer, David , Barton, Philip
- Date: 2016
- Type: Text , Journal article
- Relation: Global Change Biology Vol. 22, no. 4 (2016), p. 1325-1335
- Full Text:
- Reviewed:
- Description: Managing multiple, interacting disturbances is a key challenge to biodiversity conservation, and one that will only increase as global change drivers continue to alter disturbance regimes. Theoretical studies have highlighted the importance of a mechanistic understanding of stressor interactions for improving the prediction and management of interactive effects. However, many conservation studies are not designed or interpreted in the context of theory and instead focus on case-specific management questions. This is a problem as it means that few studies test the relationships highlighted in theoretical models as being important for ecological management. We explore the extent of this problem among studies of interacting disturbances by reviewing recent experimental studies of the interaction between fire and grazing in terrestrial ecosystems. Interactions between fire and grazing can occur via a number of pathways; one disturbance can modify the other's likelihood, intensity or spatial distribution, or one disturbance can alter the other's impacts on individual organisms. The strength of such interactions will vary depending on disturbance attributes (e.g. size or intensity), and this variation is likely to be nonlinear. We show that few experiments testing fire-grazing interactions are able to identify the mechanistic pathway driving an observed interaction, and most are unable to detect nonlinear effects. We demonstrate how these limitations compromise the ability of experimental studies to effectively inform ecological management. We propose a series of adjustments to the design of disturbance interaction experiments that would enable tests of key theoretical pathways and provide the deeper ecological understanding necessary for effective management. Such considerations are relevant to studies of a broad range of ecological interactions and are critical to informing the management of disturbance regimes in the context of accelerating global change. © 2016 John Wiley & Sons Ltd.
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