Nativity and seed dispersal mode influence species' responses to habitat connectivity and urban environments

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Jul 04, 2018
Author: 
Bianca E. Lopez, Dean Urban, Peter S. White

 

Abstract

Aim

Urbanization alters local environmental conditions and the ability of species to disperse between remnant habitat patches within the urban matrix. Nonetheless, despite the ongoing growth of urban areas worldwide, few studies have investigated the relative importance of dispersal and local environmental conditions for influencing species composition within urban and suburban landscapes. Here, we explore this question using spatial patterns of plant species composition.

Location

The Research Triangle area, which includes the cities of Raleigh, Durham, Chapel Hill and Cary, in central North Carolina, USA.

Time period

2012–2014.

Major taxa studied

Vascular plants.

Methods

We sampled riparian forest plant communities along an urban‐to‐rural gradient and used redundancy analysis to identify predictors of species composition patterns for groups of species categorized by nativity and seed dispersal mode. We first compared the ability of different models of habitat connectivity (least‐cost paths that avoided urban land cover versus Euclidean and along‐stream distance) to explain spatial patterns of species composition. We then partitioned the variation in species composition explained by habitat connectivity models, local environmental conditions and measures of urbanization in the surrounding landscape.

Results

We found that several groups of native species were best explained by least‐cost path models that avoided urban development, suggesting that urbanization impedes dispersal within this landscape, particularly for short‐dispersed species. Environmental variables related to urbanization (e.g., temperature, stream incision) were important predictors of species composition for many species groups, but measures of urbanization in the surrounding landscape were more important for exotic than for native species.

Main conclusions

Our results demonstrate that urbanization influences plant species composition via its effects on both habitat connectivity and environmental conditions. However, the strength of these effects varies somewhat predictably across seed dispersal modes and between native and exotic species. These results highlight the importance of landscape‐scale planning for urban conservation.

Read the full article in Global Ecology and Biogeography.

Associated SESYNC Researcher(s): 
DOI for citing: 
https://doi.org/10.1111/geb.12760
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