The geometric mean of relative abundance indices: a biodiversity measure with a difference

Buckland, Stephen T.; Studeny, Angelika; Magurran, Anne E.; Illian, Janine B.; Newson, Stuart E.

doi:10.1890/es11-00186.1

Cited by 80 publications

(108 citation statements)

References 33 publications

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“…Trends in abundance of species populations are a crucial indicator of biodiversity [28,29] and can provide early warnings of declines prior to species qualifying for high levels of extinction risk [30]. Consequently, this metric has been recommended as an Essential Biodiversity Variable [31], and, its use in geometric mean abundance indicators such as the Living Planet Index (LPI), is part of the mechanism to monitor biodiversity and assess progress towards the Aichi Targets.…”

Section: Discussionmentioning

confidence: 99%

The Diversity-Weighted Living Planet Index: Controlling for Taxonomic Bias in a Global Biodiversity Indicator

2017

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As threats to species continue to increase, precise and unbiased measures of the impact these pressures are having on global biodiversity are urgently needed. Some existing indicators of the status and trends of biodiversity largely rely on publicly available data from the scientific and grey literature, and are therefore prone to biases introduced through over-representation of well-studied groups and regions in monitoring schemes. This can give misleading estimates of biodiversity trends. Here, we report on an approach to tackle taxonomic and geographic bias in one such indicator (Living Planet Index) by accounting for the estimated number of species within biogeographical realms, and the relative diversity of species within them. Based on a proportionally weighted index, we estimate a global population decline in vertebrate species between 1970 and 2012 of 58% rather than 20% from an index with no proportional weighting. From this data set, comprising 14,152 populations of 3,706 species from 3,095 data sources, we also find that freshwater populations have declined by 81%, marine populations by 36%, and terrestrial populations by 38% when using proportional weighting (compared to trends of -46%, +12% and +15% respectively). These results not only show starker declines than previously estimated, but suggests that those species for which there is poorer data coverage may be declining more rapidly.

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Section: Discussionmentioning

confidence: 99%

The Diversity-Weighted Living Planet Index: Controlling for Taxonomic Bias in a Global Biodiversity Indicator

2017

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“…However, it remained possible that undetected interspecific patterns could emerge if results were averaged across species, so we calculated the geometric mean of exp a _ 0 9 across all species within each broad option category, including both significant and non-significant results (following Buckland et al 2011). Mean exp a _ 0 9 estimates whose 95% CI (calculated by combining the species-specific variances) did not include unity could reflect previously undetected interspecific management effects.…”

Section: O V E R a L L R E S P O N S E T O E S M A N A G E M E N Tmentioning

confidence: 99%

Landscape‐scale responses of birds to agri‐environment management: a test of the English Environmental Stewardship scheme

Baker

Freeman

Grice

et al. 2012

Journal of Applied Ecology

137

144

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Summary1. Agri-environment schemes (AES) are used extensively across Europe to address biodiversity declines in farmland. In England, Environmental Stewardship (ES) was introduced in 2005 to address the shortcomings of previous schemes, but as for schemes in other countries, assessments to date have revealed little evidence for national-scale biodiversity benefits. 2. Here, we assess the efficacy of ES in driving changes in national farmland bird populations over the period 2002-2010, using BTO ⁄ JNCC ⁄ RSPB Breeding Bird Survey data. We tested for associations between ES management options, grouped into categories reflecting intended biological effects (e.g. stubble), and species' population growth rates, wherever benefits of management might be expected to occur. 3. We found strong evidence for positive effects of management that provides winter food resources (i.e. ES stubble and wild bird seed [WBS] crops) on population growth rates across multiple granivorous species, at three landscape scales. The results for management aiming to provide breeding season benefits (i.e. grassland, field margin and boundary [hedge, ditch] management) showed mixed patterns of positive and negative associations. 4. The results for stubble and WBS provide the first evidence for landscape-scale responses of biodiversity to AES management. The negative relationships identified may also show the importance of management context driving unforeseen predation or competition effects. 5. Synthesis and Applications. This study demonstrates that agri-environment scheme management has the potential to have national-scale effects on avian population growth rates, although our results suggest that some components of the scheme have had little effect on bird populations. Therefore, whilst this study provides the first proof-of-concept for broad-and-shallow scheme impacts on biodiversity, our results underline the importance of targeting towards populationlimiting factors, here winter food resources. A combination of low uptake of key in-field options that provide winter seed and a failure to cover the late-winter period effectively explains the lack of national population responses. Such issues need to be addressed before schemes like Environmental Stewardship will achieve their goals. This study shows the value of feedback from monitoring for informing scheme design, through identifying problems and testing solutions.

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“…Most simply, ecologists often contrast species richness and abundances relative to sampling effort among different conditions using tests for comparing means (e.g., ANOVA, Kruskal-Wallis; [3]–[5]). Also, many indices have been developed to measure species richness and diversity (see Moreno [1], [6]–[8] for further details). However, many popular software applications do not support performing standard inferential statistics for estimates of diversity (e.g., species richness, density).…”

Section: Introductionmentioning

confidence: 99%

Contrasting Diversity Values: Statistical Inferences Based on Overlapping Confidence Intervals

2013

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Ecologists often contrast diversity (species richness and abundances) using tests for comparing means or indices. However, many popular software applications do not support performing standard inferential statistics for estimates of species richness and/or density. In this study we simulated the behavior of asymmetric log-normal confidence intervals and determined an interval level that mimics statistical tests with P(α) = 0.05 when confidence intervals from two distributions do not overlap. Our results show that 84% confidence intervals robustly mimic 0.05 statistical tests for asymmetric confidence intervals, as has been demonstrated for symmetric ones in the past. Finally, we provide detailed user-guides for calculating 84% confidence intervals in two of the most robust and highly-used freeware related to diversity measurements for wildlife (i.e., EstimateS, Distance).

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The geometric mean of relative abundance indices: a biodiversity measure with a difference

Cited by 80 publications

References 33 publications

The Diversity-Weighted Living Planet Index: Controlling for Taxonomic Bias in a Global Biodiversity Indicator

The Diversity-Weighted Living Planet Index: Controlling for Taxonomic Bias in a Global Biodiversity Indicator

Landscape‐scale responses of birds to agri‐environment management: a test of the English Environmental Stewardship scheme

Contrasting Diversity Values: Statistical Inferences Based on Overlapping Confidence Intervals

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