How Do Urban Forests Compare? Tree Diversity in Urban and Periurban Forests of the Southeastern US

Amy Blood,Christina Staudhammer,Francisco Escobedo,Gregory Starr,Art Chappelka

doi:10.3390/f7060120

Amy Blood, Christina Staudhammer + Show 3 more

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https://doi.org/10.3390/f7060120

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Abstract

There is a need to understand how anthropogenic influences affect urban and periurban forest diversity at the regional scale. This study aims to compare urban and periurban tree composition along a geographic gradient, and test hypotheses about species composition and ecological homogeneity. We paired urban forest (UF) data from eight cities across the southeastern US with periurban forest (PF) data from the USDA Forest Service Forest Inventory and Analysis program. We found that tree diversity, as well as both observed and estimated species richness values were greater in UF versus PF. Community size structure analysis also indicated a greater proportion of large trees and greater numbers of non-native, invasive, and unclassified tree species in the UF versus the PF, regardless of location. Both forest type and ecological province had a significant effect on community species composition, with forests closer together in space being more similar to each other than those more distant. While land use change and management has been associated with ecological homogenization in human dominated landscapes, we found that species composition was more dissimilar along latitudinal lines than compared to between forest types, refuting this hypothesis, at least in terms of tree diversity.

Highlights

Rapid urbanization and land use change in proximity to urban areas has led to the alteration of structure and composition of forests [1]
Our results indicate that urban tree species distributions are not geographically homogenous throughout the SE United States (US)
Urban forests in this region have maintained a fair amount of native species, and are a reflection of their respective periurban tree communities

Summary

Introduction

Rapid urbanization and land use change in proximity to urban areas has led to the alteration of structure and composition of forests [1]. Novel ecosystem assemblages have developed in both urban and periurban forests in response to land use change, as well as species introductions, ecological disturbance, and sociopolitical and economic shifts [2,3,4,5]. As natural landscapes are altered by urbanization, there is a gap in our understanding of the implications these changes might have on regional urban and periurban tree diversity. Is the species composition of urban areas more or less resistant to climate change, as compared to adjacent periurban forests?. Urban forests with low tree diversity may be at substantial risk in terms of potential alteration from ecological disturbances.

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