Person: Buckley, Hannah
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Buckley
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Hannah
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Buckley, Hannah
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Publication Using codispersion analysis to quantify and understand spatial patterns in species-environment relationships(Wiley-Blackwell, 2016) Buckley, Hannah; Case, Bradley; Zimmerman, Jess; Jill, Thompson; Myers, Jonathan; Ellison, AaronSummary 1. Analysis of spatial patterns in species-environment relationships can provide new insights about the niche requirements and potential co-occurrence of species, but species abundance and environmental data are routinely collected at different spatial scales. Here, we investigate the use of codispersion analysis to measure and assess the scale, directionality, and significance of complex relationships between plants and their environment in large forest plots. 2. We applied codispersion analysis to both simulated and field data on spatially-located tree species basal area and environmental variables. The significance of observed bivariate spatial associations between the basal area of key species and underlying environmental variables was tested using three null models. 3. Codispersion analysis reliably detected directionality (anisotropy) in bivariate species-environment relationships and identified relevant scales of effects. Null model-based significance tests applied to codispersion analyses of forest plot data enabled us to infer the extent to which environmental conditions, tree sizes, and/or tree spatial positions underpinned observed basal area-environment relationships, or whether relationships were due to other unmeasured factors. 4. Codispersion analysis, combined with appropriate null models, can be used to infer hypothesized ecological processes from spatial patterns allowing us to start disentangling the possible drivers of plant species-environment relationships.Publication Using codispersion analysis to characterize spatial patterns in species co-occurrences(Ecological Society of America, 2015) Buckley, Hannah; Case, Bradley; Ellison, AaronVisualizing and quantifying spatial patterns of co-occurrence (i.e., of two or more species, or of species and underlying environmental variables) can suggest hypotheses about processes that structure species assemblages and their relevant spatial scales. Statistical models of spatial co-occurrence generally assume that underlying spatial processes are isotropic and stationary but many ecologically realistic spatial processes are anisotropic and non-stationary. Here, we introduce codispersion analysis to ecologists and use it to detect and quantify anisotropic and nonstationary patterns and their relevant spatial scales in bivariate co-occurrence data. Simulated data illustrated that codispersion analysis can accurately characterize complex spatial patterns. Analysis of co-occurrence of common tree species growing in a 35-ha plot revealed both positive and negative codispersion between different species; positive codispersion values reflected positive correlation in species abundance (aggregation), whereas negative codispersion values reflected negative correlation in species abundance (segregation). Comparisons of observed patterns with those simulated using two different null models showed that the codispersion of most species pairs differed significantly from random expectation. We conclude that codispersion analysis can be a useful exploratory tool to guide ecologists interested in modeling spatial processes.Publication Detecting Ecological Patterns Along Environmental Gradients: Alpine Treeline Ecotones(Informa UK Limited, 2016) Buckley, Hannah; Case, Bradley; Vallejos, Ronny; Camarero, J. Julio; Gutiérrez, Emilia; Liang, Eryuan; Wang, Yafeng; Ellison, Aaron