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dc.contributor.authorKorner-Nievergelt, Fränzi
dc.contributor.authorStrebel, Nicolas
dc.contributor.authorBuckland, Stephen T.
dc.contributor.authorFreeman, Robin
dc.contributor.authorGregory, Richard D.
dc.contributor.authorGuélat, Jérôme
dc.contributor.authorIsaac, Nick
dc.contributor.authorMc Rae, Louise
dc.contributor.authorRoth, Tobias
dc.contributor.authorSchirmer, Saskia
dc.contributor.authorSoldaat, Leo L.
dc.contributor.authorVoříšek, Petr
dc.contributor.authorSattler, Thomas
dc.identifier.citationKorner-Nievergelt , F , Strebel , N , Buckland , S T , Freeman , R , Gregory , R D , Guélat , J , Isaac , N , Mc Rae , L , Roth , T , Schirmer , S , Soldaat , L L , Voříšek , P & Sattler , T 2022 , ' Multi-species population indices for sets of species including rare, disappearing or newly occurring species ' , Ecological Indicators , vol. 140 , 109005 .
dc.identifier.otherRIS: urn:09AE07B419FECFBB16053E7D55A1A50D
dc.identifier.otherORCID: /0000-0002-9939-709X/work/114023249
dc.descriptionFunding Information: NI is funded by Natural Environment Research Council award NE/R016429/1 as part of the UK-SCAPE programme delivering National Capabilityen
dc.description.abstractMulti-species indices (MSI) are widely used as ecological indicators and as instruments to inform environmental policies. Many of these indices combine species-specific estimates of relative population sizes using the geometric mean. Because the geometric mean is not defined when values of zero occur, usually only commoner species are included in MSIs and zero values are replaced by a small non-zero value. The latter can exhibit an arbitrary influence on the geometric mean MSI. Here, we show how the compound Poisson and the negative binomial model can be used in such cases to obtain an MSI that has similar features to the geometric mean, including weighting halving and doubling of a species’ population equally. In contrast to the geometric mean, these two statistical models can handle zero values in population sizes and thus accommodate newly occurring and temporarily or permanently disappearing species in the MSI. We compare the MSIs obtained by the two statistical models with the geometric mean MSI and measure sensitivity to changes in evenness and to population trends in rare and abundant species. Additionally, we outline sources of uncertainty and discuss how to measure them. We found that, in contrast to the geometric mean and the negative binomial MSI, the compound Poisson MSI is less sensitive to changes in evenness when total abundance is constant. Further, we found that the compound Poisson model can be influenced more than the other two methods by trends of species showing a low interannual variance. The negative binomial MSI is less sensitive to trends in rare species compared with the other two methods, and similarly sensitive to trends in abundant species as the geometric mean. While the two new MSIs have the advantage that they are not arbitrarily influenced by rare, newly appearing and disappearing species, both do not weight all species equally. We recommend replacing the geometric mean MSI with either compound Poisson or negative binomial when there are species with a population size of zero in some years having a strong influence on the geometric mean MSI. Further, we recommend providing additional information alongside the MSIs. For example, it is particularly important to give an evenness index in addition to the compound Poisson MSI and to indicate the number of disappearing and newly occurring species alongside the negative binomial MSI.
dc.relation.ispartofEcological Indicatorsen
dc.subjectMulti-species population indicatoren
dc.subjectTweedie compound Poisson distributionen
dc.subjectNegative binomial distributionen
dc.subjectLog-normal distributionen
dc.subjectGeometric meanen
dc.subjectPopulation size of zeroen
dc.subjectCount of zeroen
dc.subjectQA Mathematicsen
dc.subjectQL Zoologyen
dc.subjectEcology, Evolution, Behavior and Systematicsen
dc.subjectDecision Sciences(all)en
dc.titleMulti-species population indices for sets of species including rare, disappearing or newly occurring speciesen
dc.typeJournal articleen
dc.contributor.institutionUniversity of St Andrews. School of Mathematics and Statisticsen
dc.contributor.institutionUniversity of St Andrews. Scottish Oceans Instituteen
dc.contributor.institutionUniversity of St Andrews. St Andrews Sustainability Instituteen
dc.contributor.institutionUniversity of St Andrews. Centre for Research into Ecological & Environmental Modellingen
dc.contributor.institutionUniversity of St Andrews. Marine Alliance for Science & Technology Scotlanden
dc.description.statusPeer revieweden

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