Substantial long-term effects of carcass addition on soil and plants in a grassy eucalypt woodland
- Authors: Barton, Philip , McIntyre, Sue , Evans, Maldwyn , Bump, Joseph , Cunningham, Saul , Manning, Adrian
- Date: 2016
- Type: Text , Journal article
- Relation: Ecosphere Vol. 7, no. 10 (2016), p.
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- Description: The decomposition of large vertebrate carcasses generates small-scale disturbances characterized by changes in soil chemistry and new opportunities for plant establishment. Yet few studies have examined whether this effect is still evident several years after death, or has consequences for landscape-scale heterogeneity. We examined soil chemistry and plant species richness and composition at 12 kangaroo carcasses (~30 kg initial mass) five years after their initial placement. Each carcass was paired with a nearby "control" site for comparison. We found that soil phosphorus was eight times higher at carcasses than at control sites, but that nitrogen concentration was similar. We also found that plant composition was substantially different between each carcass and control pair, with 80% of carcasses dominated by exotic species (mostly weedy annuals). Notably, overall variability in plant species composition across carcass sites was not different from the variability at control sites, indicating that the colonization of carcasses by weedy species did not have a homogenizing effect on plant assemblages across our study landscape. Our study demonstrates that a localized effect of large vertebrate carcasses on soil and plants was still evident after five years, indicating a state shift in the soil-plant dynamics at a carcass site. However, the effect of carcasses on landscape-scale plant community heterogeneity was minimal because colonization was by weedy plants already present in the landscape. © 2016 Barton et al.
Does wing morphology affect recolonization of restored farmland by ground-dwelling beetles?
- Authors: Gibb, Heloise , Retter, Bryony , Cunningham, Saul , Barton, Philip
- Date: 2017
- Type: Text , Journal article
- Relation: Restoration Ecology Vol. 25, no. 2 (2017), p. 234-242
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- Description: Revegetation of previously cleared land is widely used to increase habitat area and connectivity of remnant vegetation for biodiversity conservation. Whether new habitat attracts or supports fauna depends on the dispersal traits of those fauna as well as the structure and composition of the surrounding landscape. Here, we examined wing morphology as a key dispersal trait for beetles in a revegetated landscape and asked, first, how it was related to phylogeny (family), trophic position, and body size. Second, we asked if wing morphology of recolonizing (or persisting) beetles varied with habitat characteristics at multiple scales, from microhabitat to landscape context. Third, we examined how common winged and wingless species responded to habitat at multiple scales. We measured the wing morphology of ground-dwelling beetles from a restoration chronosequence, including paddocks, “young” revegetation (8–11 years old), “old” revegetation (14–19 years old), and fenced remnant vegetation. We found that body size and family membership were significant predictors of winglessness, with wingless species of carabids and curculionids being larger than their winged counterparts. We found no difference in the number of sites occupied by winged and wingless species, and no relationship between the wing morphology traits represented in different locations and habitat characteristics or landscape context. Furthermore, the most abundant species of both winged and wingless ground-dwelling beetles had relatively little affinity to any habitat successional stage. Thus, despite intrinsic differences in wing morphology among species of ground-dwelling beetle, we found no evidence that flight-related dispersal limitations influenced recolonization (or persistence) in this landscape. © 2016 Society for Ecological Restoration
Environmental and spatial drivers of spider diversity at contrasting microhabitats
- Authors: Barton, Philip , Evans, Maldwyn , Foster, Claire , Cunningham, Saul , Manning, Adrian
- Date: 2017
- Type: Text , Journal article
- Relation: Austral Ecology Vol. 42, no. 6 (2017), p. 700-710
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- Description: The relative importance of environmental and spatial drivers of animal diversity varies across scales, but identifying these scales can be difficult if a sampling design does not match the scale of the target organisms' interaction with their habitat. In this study, we quantify and compare the effects of environmental variation and spatial proximity on ground-dwelling spider assemblages sampled from three distinct microhabitat types (open grassland, logs, trees) that recur across structurally heterogeneous grassy woodlands. We used model selection and multivariate procedures to compare the effects of different environmental attributes and spatial proximity on spider assemblages at each microhabitat type. We found that species richness and assemblage composition differed among microhabitat types. Bare ground cover had a negative effect on spider richness under trees, but a positive effect on spider richness in open grassland. Turnover in spider assemblages from open grassland was correlated with environmental distance, but not geographic distance. By contrast, turnover in spiders at logs and trees was correlated with geographic distance, but not environmental distance. Our study suggests that spider assemblages from widespread and connected open grassland habitat were more affected by environmental than spatial gradients, whereas spiders at log and tree habitats were more affected by spatial distance among these discrete but recurring microhabitats. Deliberate selection and sampling of small-scale habitat features can provide robust information about the drivers of arthropod diversity and turnover in landscapes. © 2017 Ecological Society of Australia
Fine-scale drivers of beetle diversity are affected by vegetation context and agricultural history
- Authors: Ross, Catherine , Barton, Philip , McIntyre, Sue , Cunningham, Saul , Manning, Adrian
- Date: 2017
- Type: Text , Journal article
- Relation: Austral Ecology Vol. 42, no. 7 (2017), p. 831-843
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- Description: Environmental gradients have been shown to affect animal diversity, but knowledge of fine-scale drivers of insect diversity is, in many cases, poorly developed. We investigated the drivers of beetle diversity and composition at different microhabitats, and how this may be mediated by past agricultural activities. The study was undertaken in temperate eucalypt grassy woodland near Canberra, south-eastern Australia, with a 200-year history of pastoral land use. We sampled beetles using pitfall traps at three microhabitats (open grassland, logs and under trees). We analysed the effects of soil properties, vegetation structure, and plant composition on beetle composition, and compared beetle responses among the microhabitats. We found that microhabitat was a strong determinant of the way beetle communities responded to their environment. Soil nutrients (C, N and P) were the strongest drivers of beetle species richness, abundance and composition at open and log microhabitat, however vegetation structure (tree basal area) was more important for beetle richness, abundance and biomass under trees. We also found significant differences in beetle composition among distinct ground-layer plant communities at log and tree microhabitat. We show that prior agricultural land use, particularly fertilization, has altered soil and plant communities, and that these effects continue to flow through the system affecting beetle assemblages. These findings have implications for future management of microhabitat structures in temperate grassy woodlands with a history of agricultural use. © 2017 Ecological Society of Australia
Species co-occurrence networks show reptile community reorganization under agricultural transformation
- 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
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- 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
Beetle ecological indicators – A comparison of cost vs reward to understand functional changes in response to restoration actions
- Authors: Evans, Maldwyn , Cunningham, Saul , Gibb, Heloise , Manning, Adrian , Barton, Philip
- Date: 2019
- Type: Text , Journal article
- Relation: Ecological Indicators Vol. 104, no. (2019), p. 209-218
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- Description: Ecosystem restoration can play a vital role in conserving biodiversity, but its effectiveness can be difficult to assess for hyperdiverse biota such as insects. Species traits of insects can be used to understand their functional responses to restoration, but their use often requires considerable effort, and few studies have examined what additional insight can be gained from this approach. We used a spatially and temporally controlled restoration experiment to examine beetle species, grouped by flight ability, family membership and feeding guild, as indicators of ecosystem functional change. We tested for the effects of reduced vertebrate grazing on beetle assemblages sampled from two different microhabitats (next to log and in open ground)one year prior and two years after a vertebrate grazing treatment was applied. We compared the responses of the different beetle functional groupings, and then related these to the effort involved in employing these indicators. We found that beetle species traits gave several functional insights into their responses to reduced grazing, including responses to changes in vegetation structure and biomass. Species richness indicators and abundance indicators of beetle functional groups showed similar responses in many cases, whereas biomass indicators gave additional insights related to the extra biomass of vegetation and detritus resulting from the reduction in grazing. We found that most results were revealed by using family groups as indicators for functional change. This is because the traits that often define beetle families, such as size, flight ability and feeding guilds each have distinctive functional roles, allowing a link from family to function, and supporting the idea that phylogeny is often a useful shortcut to species ecology. We conclude that in our study system, the least-cost approach to identifying functional responses of beetles to reduced vertebrate grazing, and possibly other restoration actions, is to use abundance indicators of the most common family groups. © 2019 Elsevier Ltd
Conserving focal insect groups in woodland remnants : the role of landscape context and habitat structure on cross-taxonomic congruence
- Authors: Yong, Ding , Barton, Philip , Okada, Sachiko , Crane, Mason , Cunningham, Saul , Lindenmayer, David
- Date: 2020
- Type: Text , Journal article
- Relation: Ecological Indicators Vol. 115, no. (2020), p.
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- Description: Determining the shared responses of different taxa to landscape modification is a key step for identifying which groups of species are good surrogates for other groups. Yet, surprisingly little is known about the spatial processes that drive cross-taxonomic congruence of diversity and how this knowledge can be used to improve the management of modified landscapes for biodiversity, especially insects. We investigated how assemblages of two ecologically important insect groups, wild bees and beetles, respond to different landscape contexts and habitat structure in an Australian agricultural landscape, and how this, in turn, influenced either group's potential as a surrogate for the other. Bee and ground-active beetle assemblages were sampled in remnant woodland patches in two landscape contexts: woodland patches surrounded by pine plantation and woodland patches surrounded by open grazing land. Bee species richness, and the richness of functionally-defined bee groups did not differ between landscape contexts, in contrast to beetles. We found that landscape context exerted a stronger effect on species composition than species richness of both groups. Although some landscape and habitat variables were useful in predicting the diversity of both insect groups, few were shared. Our findings showed that bee and beetles are poor surrogates for each other in landscapes that are highly modified. Our study highlighted the need to consider: (1) taxon-specific responses to landscape context, (2) the influence of different metrics of cross-taxonomic surrogacy and, (3) dissimilar ecological attributes among insect taxa when selecting insects as biodiversity surrogates. It should not be assumed that agricultural landscapes managed to conserve specific insects (e.g. bees) will necessarily benefit other insects. © 2020
How bioregional history could shape the future of agriculture
- Authors: Brown, Julian , Barton, Philip , Cunningham, Saul
- Date: 2021
- Type: Text , Book chapter
- Relation: Advances in Ecological Research p. 149-189
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- Description: Biodiversity conservation and agriculture are becoming intimately intertwined. Wildlife-friendly agriculture is promoted as a way to conserve biodiversity, connect nature reserves, facilitate climate-driven range shifts and enhance ecosystem services to agriculture. Yet some approaches that increase native biodiversity in agricultural landscapes, such as tropical agroforestry, may support a suite of species that is distinct from nearby remnant habitat. Wildlife-friendly farming, therefore, does not necessarily facilitate native species persistence through landscape conversion to agriculture or facilitate the movement of local species among nature reserves. We argue the historical composition of native species in agricultural landscapes can be maintained by enhancing ecological similarity between production land uses and natural ecosystems. Some agricultural systems already support native species from, and share some ecological attributes with, natural grasslands, wetlands and forests. However, we suggest there are benefits to be gained by focusing on the finer details of similarities in structure, floristic composition (e.g. crop species) and disturbance regimes occurring across natural and modified habitat types. A key advancement of this approach is that the composition of agricultural diversity and its spatio-temporal dynamics are selected and managed according to the spatial and temporal habitat requirements of the wildlife species naturally inhabiting the local area. We argue that ensuring ecological similarity between agricultural systems and the ecosystems they replaced or lie between will strengthen the capacity of agricultural landscapes to maintain historical species pools and provide spatial and temporal connectivity between nature reserves and analogous future climatic zones. © 2021 Elsevier Ltd