Taxonomic and functional diversity change is scale dependent

Marta A Jarzyna,Walter Jetz

doi:10.1038/s41467-018-04889-z

Marta A Jarzyna, Walter Jetz

Open Access

https://doi.org/10.1038/s41467-018-04889-z

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Journal: Nature Communications	Publication Date: Jul 2, 2018
Citations: 120	License type: open-access

Affiliation: Yale University, Imperial College London

Abstract

Estimates of recent biodiversity change remain inconsistent, debated, and infrequently assessed for their functional implications. Here, we report that spatial scale and type of biodiversity measurement influence evidence of temporal biodiversity change. We show a pervasive scale dependence of temporal trends in taxonomic (TD) and functional (FD) diversity for an ~50-year record of avian assemblages from North American Breeding Bird Survey and a record of global extinctions. Average TD and FD increased at all but the global scale. Change in TD exceeded change in FD toward large scales, signaling functional resilience. Assemblage temporal dissimilarity and turnover (replacement of species or functions) declined, while nestedness (tendency of assemblages to be subsets of one another) increased with scale. Patterns of FD change varied strongly among diet and foraging guilds. We suggest that monitoring, policy, and conservation require a scale-explicit framework to account for the pervasive effect that scale has on perceived biodiversity change.

Highlights

Estimates of recent biodiversity change remain inconsistent, debated, and infrequently assessed for their functional implications
Our results indicate that scale-explicit framework should be adopted in monitoring, policy, and conservation to account for the pervasive effect that scale has on perceived biodiversity change
We find that scaling of FDΔ and TDΔ followed each other closely at local and intermediate spatial scales, but |FDΔ| was increasingly exceeded by |TDΔ| toward coarser scales (Fig. 3a, Supplementary Figs. 4–5), suggesting—as expected—strong trait clustering and redundancy at those scales

Summary

Introduction

Estimates of recent biodiversity change remain inconsistent, debated, and infrequently assessed for their functional implications. We show a pervasive scale dependence of temporal trends in taxonomic (TD) and functional (FD) diversity for an ~50-year record of avian assemblages from North American Breeding Bird Survey and a record of global extinctions. Taxonomic diversity (species richness (TD)) remains the main measure of biodiversity despite the recognition that it does not account for the many different ecological functions[14,15] of species comprising communities and may not account for the implications of biodiversity change for the functioning of ecosystems and their services for humans[5,16]. We use uniquely suited, detection-corrected[23], and nearcontinental data from the North American Breeding Bird Survey (BBS) from a nearly 50-year period, and extended to extinctions at the global scale[24], to demonstrate a pervasive scale and metric dependence of taxonomic and functional diversity change. Our results indicate that scale-explicit framework should be adopted in monitoring, policy, and conservation to account for the pervasive effect that scale has on perceived biodiversity change

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