Higher-taxon and functional group responses of ant and bird assemblages to livestock grazing : a test of an explicit surrogate concept
- Barton, Philip, Evans, Maldwyn, Sato, Chloe, O'Loughlin, Luke, Foster, Claire
- Authors: Barton, Philip , Evans, Maldwyn , Sato, Chloe , O'Loughlin, Luke , Foster, Claire
- Date: 2019
- Type: Text , Journal article
- Relation: Ecological Indicators Vol. 96, no. (2019), p. 458-465
- Full Text:
- Reviewed:
- Description: Biodiversity monitoring programs are routinely established to quantify changes in biotic communities in response to land management. Surrogacy is implicitly used in many such monitoring programs whereby the measurement of a component of biodiversity is used to infer responses of broader biodiversity. Yet rarely is this surrogacy validated by demonstrating that measured variables and the target variable of interest have matching responses to management treatments. Here we examined the responses of higher-taxon and functional groupings of ants and birds (our surrogate variables) two years after the implementation of experimental livestock grazing treatments, and compared these with the responses of total ant and bird species richness (our target variables) to the same treatments. We found significant and strong correlations between surrogate and target variables, but this did not predict corresponding similar response to treatments. For ants, we found that the genus Monomorium had a negative response to the grazing exclusion treatment, but there was no matching response of species richness, and so no surrogacy was identified. For birds, total species richness had a weak positive response to spring/summer grazing exclusion, and the abundance of honeyeaters (Meliphagidae) showed a similar positive response, suggesting surrogacy. Our study highlights that correlations among variables do not necessarily lead to surrogacy, and indeed that different sub-components of biotic assemblages can respond in ways that contrast with overall species richness. Careful assessment of the matched responses of surrogate and target variables to management can provide a simple and robust way to critically assess biodiversity surrogacy. © 2018 Elsevier Ltd. **Please note that there are multiple authors for this article therefore only the name of the first 5 including Federation University Australia affiliate “Philip Barton” is provided in this record**
- Authors: Barton, Philip , Evans, Maldwyn , Sato, Chloe , O'Loughlin, Luke , Foster, Claire
- Date: 2019
- Type: Text , Journal article
- Relation: Ecological Indicators Vol. 96, no. (2019), p. 458-465
- Full Text:
- Reviewed:
- Description: Biodiversity monitoring programs are routinely established to quantify changes in biotic communities in response to land management. Surrogacy is implicitly used in many such monitoring programs whereby the measurement of a component of biodiversity is used to infer responses of broader biodiversity. Yet rarely is this surrogacy validated by demonstrating that measured variables and the target variable of interest have matching responses to management treatments. Here we examined the responses of higher-taxon and functional groupings of ants and birds (our surrogate variables) two years after the implementation of experimental livestock grazing treatments, and compared these with the responses of total ant and bird species richness (our target variables) to the same treatments. We found significant and strong correlations between surrogate and target variables, but this did not predict corresponding similar response to treatments. For ants, we found that the genus Monomorium had a negative response to the grazing exclusion treatment, but there was no matching response of species richness, and so no surrogacy was identified. For birds, total species richness had a weak positive response to spring/summer grazing exclusion, and the abundance of honeyeaters (Meliphagidae) showed a similar positive response, suggesting surrogacy. Our study highlights that correlations among variables do not necessarily lead to surrogacy, and indeed that different sub-components of biotic assemblages can respond in ways that contrast with overall species richness. Careful assessment of the matched responses of surrogate and target variables to management can provide a simple and robust way to critically assess biodiversity surrogacy. © 2018 Elsevier Ltd. **Please note that there are multiple authors for this article therefore only the name of the first 5 including Federation University Australia affiliate “Philip Barton” is provided in this record**
Do temporal changes in vegetation structure additional to time since fire predict changes in bird occurrence?
- Lindenmayer, David, Candy, Steven, MacGregor, Christopher, Banks, Sam, Barton, Philip
- Authors: Lindenmayer, David , Candy, Steven , MacGregor, Christopher , Banks, Sam , Barton, Philip
- Date: 2016
- Type: Text , Journal article
- Relation: Ecological Applications Vol. 26, no. 7 (2016), p. 2267-2279
- Full Text:
- Reviewed:
- Description: Fire is a major ecological process in ecosystems globally. Its impacts on fauna can be both direct (e.g., mortality) and indirect (e.g., altered habitat), resulting in population recovery being driven by several possible mechanisms. Separating direct from indirect impacts of fire on faunal population recovery can be valuable in guiding management of biodiversity in fire-prone environments. However, resolving the influence of direct and indirect processes remains a key challenge because many processes affecting fauna can change concomitantly with time since fire. We explore the mechanisms influencing bird response to fire by posing the question, can temporal changes in vegetation structure predict changes in bird occurrence on sites, and can these be separated from other temporal changes using the surrogate of time since fire? We conducted a 12-yr study of bird and vegetation responses to fire at 124 sites across six vegetation classes in Booderee National Park, Australia. Approximately half of these sites, established in 2002, were burned by a large (>3000 ha) wildfire in 2003. To disentangle collinear effects of temporal changes in vegetation and direct demographic effects on population recovery that are subsumed by time since fire, we incorporated both longitudinal and cross-sectional vegetation effects in addition to time since fire within logistic structural equation models. We identified temporal changes in vegetation structure and richness of plant and bird species that characterized burned and unburned sites in all vegetation classes. For nine bird species, a significant component of the year trend was driven by temporal trends in one of three vegetation variables (number of understory or midstory plant species, or midstory cover). By contrast, we could not separate temporal effects between time since fire and vegetation attributes for bird species richness, reporting rate, and the occurrence of 11 other bird species. Our findings help identify species for which indirect effects of vegetation dominate recovery and thus may benefit from vegetation management where conservation actions are required and, conversely, those species for which direct effects of time since fire drive recovery, where simply leaving a system to recover following the last disturbance will be sufficient. © 2016 by the Ecological Society of America.
- Authors: Lindenmayer, David , Candy, Steven , MacGregor, Christopher , Banks, Sam , Barton, Philip
- Date: 2016
- Type: Text , Journal article
- Relation: Ecological Applications Vol. 26, no. 7 (2016), p. 2267-2279
- Full Text:
- Reviewed:
- Description: Fire is a major ecological process in ecosystems globally. Its impacts on fauna can be both direct (e.g., mortality) and indirect (e.g., altered habitat), resulting in population recovery being driven by several possible mechanisms. Separating direct from indirect impacts of fire on faunal population recovery can be valuable in guiding management of biodiversity in fire-prone environments. However, resolving the influence of direct and indirect processes remains a key challenge because many processes affecting fauna can change concomitantly with time since fire. We explore the mechanisms influencing bird response to fire by posing the question, can temporal changes in vegetation structure predict changes in bird occurrence on sites, and can these be separated from other temporal changes using the surrogate of time since fire? We conducted a 12-yr study of bird and vegetation responses to fire at 124 sites across six vegetation classes in Booderee National Park, Australia. Approximately half of these sites, established in 2002, were burned by a large (>3000 ha) wildfire in 2003. To disentangle collinear effects of temporal changes in vegetation and direct demographic effects on population recovery that are subsumed by time since fire, we incorporated both longitudinal and cross-sectional vegetation effects in addition to time since fire within logistic structural equation models. We identified temporal changes in vegetation structure and richness of plant and bird species that characterized burned and unburned sites in all vegetation classes. For nine bird species, a significant component of the year trend was driven by temporal trends in one of three vegetation variables (number of understory or midstory plant species, or midstory cover). By contrast, we could not separate temporal effects between time since fire and vegetation attributes for bird species richness, reporting rate, and the occurrence of 11 other bird species. Our findings help identify species for which indirect effects of vegetation dominate recovery and thus may benefit from vegetation management where conservation actions are required and, conversely, those species for which direct effects of time since fire drive recovery, where simply leaving a system to recover following the last disturbance will be sufficient. © 2016 by the Ecological Society of America.
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