Extrapolating population size from the occupancy–abundance relationship and the scaling pattern of occupancy

Hui, Cang; McGeoch, Mélodie A.; Reyers, Belinda; Roux, Peter C. le; Greve, Michelle; Chown, Steven Loudon

doi:10.1890/08-2236.1

Cited by 55 publications

(68 citation statements)

References 74 publications

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“…Such non-process based methodology emphasizes on crossscale pattern consistency and constraints (e.g. Hui et al 2006;Hui 2009;Harte 2011) and has been shown to outperform many process-based methods for inferring fine scale occupancies and abundances (Hui et al 2009;Barwell et al 2014). Such inferences reflect the most probable or likely predictions without additional information/processes assumed.…”

Section: Discussionmentioning

confidence: 99%

Quantifying multiple-site compositional turnover in an Afrotemperate forest, using zeta diversity

Hui

Durrheim

2018

For. Ecosyst.

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Background: Species turnover is typically measured by partitioning diversity components into alpha and pairwise beta diversity. However, alpha and beta components cannot express the full spectrum of multiple-site compositional turnover. To this end, zeta diversity has been proposed as an extended framework to allow complete biodiversity partitioning and to measure multiple-site species turnover. We use a zeta-diversity framework to explore the turnover and potential community assembly processes of an African Montane Forest. Methods: Using a 20 m grid, we explore the species turnover in a 4.55 ha forest plot located in the Garden Route National Park of South Africa, with 47 and 27 canopy and sub-canopy tree species in the regional pool. We first calculate how zeta diversity declines and how the probability of retention of species with particular occupancies changes with increasing zeta orders (i.e. the number of sites [grid cells] involved in the calculation). Using null models with row sums and column sums constrained respectively, we explore whether species turnover is driven by mechanisms of ecological differences (species-specific occupancies) or habitat heterogeneity (site-specific alpha diversity and thus environmental filters). Results: The decline of zeta diversity with zeta order followed a power law; that is, the probability of retention increased with species occupancies, suggesting common species being more likely to be discovered in extra sites. The null model retaining row sums (species' occupancy) of the species-by-site matrix recreated perfectly the decline of zeta diversity, while the null model of habitat heterogeneity (retaining column sums) was rejected. This suggests that mechanisms driving species-specific occupancies (i.e. ecological differences between species) dictate the multi-site species turnover in the community. The spatial patterns of zeta diversity revealed little spatial structuring forces, supporting a fine-grain structure in these southern Cape forests. Conclusions: The framework of zeta diversity revealed mechanisms driving the large discrepancies in the occupancy among species that are behind the species turnover in the African Montane forest plot. Future studies could further link species turnover to spatial distance decay. Environmental filters and temporal turnover from landscape demography could bring a cohesive understanding of community assembly in these unique forest ecosystems.

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Section: Discussionmentioning

confidence: 99%

Quantifying multiple-site compositional turnover in an Afrotemperate forest, using zeta diversity

Hui

Durrheim

2018

For. Ecosyst.

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“…It has many merits (Hui et al 2009), but would have been difficult to apply in the present case. In fact, at each resolution it needs spatially explicit occupancy information that is not available in many data sets as well as in the empirical data we considered in this study.…”

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confidence: 87%

“…In recent years the issue of species occupancy at different spatial scales has been of growing interest in spatial ecology (Kunin 1998, He and Gaston 2000, Kunin et al 2000, Tosh et al 2004, Hui et al 2009). Species occupancy, or the fraction of area occupied by a given species, is obtained by dividing the study area into an artificial regular grid of cells of (ideally) equal size and then calculating the fraction of such cells occupied by a focal species.…”

Section: Introductionmentioning

confidence: 99%

Downscaling species occupancy from coarse spatial scales

Azaele

Cornell

Kunin

2012

Ecological Applications

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Abstract. The measurement and prediction of species' populations at different spatial scales is crucial to spatial ecology as well as conservation biology. An efficient yet challenging goal to achieve such population estimates consists of recording empirical species' presence and absence at a specific regional scale and then trying to predict occupancies at finer scales. So far the majority of the methods have been based on particular species' distributional features deemed to be crucial for downscaling occupancy. However, only a minority of them have dealt explicitly with specific spatial features. Here we employ a wide class of spatial point processes, the shot noise Cox processes (SNCP), to model species occupancies at different spatial scales and show that species' spatial aggregation is crucial for predicting population estimates at fine scales starting from coarser ones. These models are formulated in continuous space and locate points regardless of the arbitrary resolution that one employs to study the spatial pattern. We compare the performances of nine models, calibrated at regional scales and demonstrate that a very simple class of SNCP, the Thomas process, is able to outperform other published models in predicting occupancies down to areas four orders of magnitude smaller than the ones employed for the parameterization. We conclude by explaining the ability of the approach to infer spatially explicit information from spatially implicit measures, the potential of the framework to combine niche and spatial models, and the possibility of reversing the method to allow upscaling.

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“…Therefore, abundance is more readily estimated from the invaded area (i.e. condensed area or the net area of infestation) (Hui et al 2009). This, in essence, is a measure of extent-area of occupancy (AOO) at a fine spatial scale-but as a simple metric of relative abundance for invasive populations it provides a useful link to impact and management.…”

Section: Estimating Current Impactsmentioning

confidence: 99%

A standardized set of metrics to assess and monitor tree invasions

et al. 2013

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Scientists, managers, and policy-makers need functional and effective metrics to improve our understanding and management of biological invasions. Such metrics would help to assess progress towards management goals, increase compatibility across administrative borders, and facilitate comparisons between invasions. Here we outline key characteristics of tree invasions (status, abundance, spatial extent, and impact), discuss how each of these characteristics changes with time, and examine potential metrics to describe and monitor them. We recommend quantifying tree invasions using six metrics: (a) current status in the region; (b) potential status; (c) the number of foci requiring management; (d) area of occupancy (AOO) (i.e. compressed canopy area or net infestation); (e) extent of occurrence (EOO)(i.e. range size or gross infestation); and (f) observa-tions of current and potential impact. We discuss how each metric can be parameterised (e.g. we include a practical method for classifying the current stage of invasion for trees following Blackburn's unified framework for biological invasions); their potential management value (e.g. EOO provides an indication of the area over which management is needed); and how they can be used in concert (e.g. combining AOO and EOO can provide insights into invasion dynamics; and we use potential status and threat together to develop a simple risk analysis tool). Based on these metrics, we propose a standardized template for reporting tree invasions that we hope will facilitate cross-species and inter-regional comparisons. While we feel this represents a valuable step towards standardized reporting, there is an urgent need to develop more consistent metrics for impact and threat, and for many specific purposes additional metrics are still needed (e.g. detectability is required to assess the feasibility of eradication).

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Extrapolating population size from the occupancy–abundance relationship and the scaling pattern of occupancy

Cited by 55 publications

References 74 publications

Quantifying multiple-site compositional turnover in an Afrotemperate forest, using zeta diversity

Quantifying multiple-site compositional turnover in an Afrotemperate forest, using zeta diversity

Downscaling species occupancy from coarse spatial scales

A standardized set of metrics to assess and monitor tree invasions

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