The relative effects of forest amount, forest configuration, and urban matrix quality on forest breeding birds

Alexandra Shoffner,Sara A Gagné,Wenwu Tang,Andrew M Wilson

doi:10.1038/s41598-018-35276-9

Alexandra Shoffner, Sara A Gagné + Show 2 more

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https://doi.org/10.1038/s41598-018-35276-9

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Abstract

Urbanization modifies landscape structure in three major ways that impact avian diversity in remnant habitat: habitat amount is reduced and habitat configuration and matrix quality are altered. The relative effects of these three components of landscape structure are relatively well-studied in agricultural landscapes, but little is known about the relative effect of urban matrix quality. We addressed this gap by investigating the relative effects of forest amount, forest configuration, and matrix quality, indicated by degree of urbanization and agriculture amount, on the diversity of three guilds of forest birds using data from 13,763 point counts from Pennsylvania, USA. Forest amount had the largest independent effect on forest bird diversity, followed by matrix quality, then forest configuration. In particular, urbanization had strong negative effects on the relative abundance and species evenness of all forest birds and the relative abundance of forest generalist birds. To our knowledge, these are the first results of the effect of urban matrix quality on forest bird relative abundance and species evenness independent of forest amount and forest configuration. Our results imply that conservation practitioners in human-modified landscapes prioritize maximizing forest amount, then reducing the effects of disturbances originating in the matrix, and then preserving large, spatially-dispersed forest patches to most effectively conserve forest birds.

Highlights

The projected doubling of developed land in the USA in the first quarter of this century[1] was and will continue to be a significant contributor to biodiversity loss[2]
Landscape variables in the best models of forest bird diversity were measured at four spatial scales: 0.2 km for models of all forest bird relative abundance, species richness, and species evenness and forest generalist bird species evenness; 1 km for the best model of forest-area sensitive bird species richness; 6 km for models of the relative abundance and species evenness of forest-area sensitive birds and the relative abundance of forest generalist birds; and, 10 km for the best model of forest generalist bird species richness
Urbanization was the only landscape structure variable of interest that had a meaningful effect on the diversity of all forest birds (relative abundance: β = −0.06 (−0.08, −0.04); species evenness: β = −0.04 (−0.06, −0.02)) (Fig. 1, see Supplementary Figs S1, S2)

Summary

Introduction

The projected doubling of developed land in the USA in the first quarter of this century[1] was and will continue to be a significant contributor to biodiversity loss[2]. Three major aspects of landscape structure have important effects on avian diversity in remnant habitat in urban landscapes: habitat amount, habitat configuration, and matrix quality. Smith et al.[4] found that total habitat amount had strong and consistently positive effects on the presence of forest birds within human-altered landscapes. Habitat amount has been hypothesized to positively influence biodiversity by means of passive sampling, higher habitat diversity, and lower extinction rates due to larger population sizes or less frequent and intense disturbances[5]. Habitat configuration has been hypothesized to affect biodiversity through a number of different mechanisms: the reduced persistence of small, isolated populations in small patches, negative or positive edge effects, increased predator-prey system stability through the provision www.nature.com/scientificreports/. Variation in matrix quality may be associated with varying disturbance occurrence, intensity, and frequency in habitat patches, such as human trail use[15]

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