Rural land use bifurcation in the urban-rural gradient
Robert J. Warren II
1
&
Katelyn Reed
1
&
Michael Olejnizcak
1
&
Daniel L. Potts
1
Published online: 6 February 2018
#
Springer Science+Business Media, LLC, part of Springer Nature 2018
Abstract
The classic urban-rural gradient concept assumes a decline in land use intensity from an intensively developed urban core
outward to residential suburbs, culminating in lightly developed rural areas. The concept provides a common framework
directing urban socio-ecological research. Given that rural land use includes woodlands and croplands, and croplands appear
as ecologically depauperate as urban lands, we investigated land-use patterns along urban-rural gradients for 30 large metropol-
itan areas in the eastern United States. We predicted a bifurcation at the rural end of the gradient between woodland and cropland
land use that does not correspond with human population density (expected to be relatively low in rural areas regardless of land
use type). Our data indicated that ‘rural’ was a poor substitute for ‘natural’ as the rural end of the gradients bifurcated at the rural
end between woodland and cropland – croplands being demonstratively poor ecological habitats. Indeed, we found that when
defined by habitat quality, the habitat known to be biotically homogenized (urban and cropland) remained steady along the urban-
rural gradient. Our results do not undermine the utility of the urban-rural gradient framework, but do suggest that the gradient and/
or human population density do not necessarily indicate shifts in habitat quality.
Keywords Biotic homogenization
.
Cropland
.
Population density
.
Urbanization
.
Woodland
Introduction
The classic urban-rural gradient concept provides a common
framework often used to direct urban socio-ecological
research. At heart, the concept assumes a decline in land
use intensity from an intensively developed urban core out-
ward to residential suburbs, culminating in lightly developed
rural areas containing woodlands and croplands. Urban ecol-
ogists regularly use the rural-urban gradient concept to inform
study design and interpretation. (Luck and Smallbone 2010;
McDonnell and Hahs 2008; Ramalho and Hobbs 2012).
McDonnell and Pickett (1990) proposed the urban-rural
gradient approach to implement a well-established research
paradigm in ecology: gradient studies (e.g., elevation, latitude,
moisture) to investigate corresponding changes in populations,
communities and ecosystems; the correlations between puta
tive drivers and responses are used to make inferences about
underlying processes (McDonnell and Pickett 1990;Whittaker
1956, 1978). Similarly, urban-rural gradients are used to exam-
ine spatial changes in putative urban drivers and/or urban prox-
ies (e.g., human population, impervious surface, socioeconom-
ic status) and ecological response (e.g., species richness, soil
processes, species invasion) (Blair 1996;Evans2010;Koerner
and Klopatek 2010;Luck2007;LuckandSmallbone2010;
McKinney 2008). Essentially, then, the impetus behind the
urban-rural gradient approach is that urbanization forms an
intensive and large-scale experimental manipulation that re-
searchers can use to study ecological responses (McDonnell
and Pickett 1990) – the responses expected to shift from inten-
sively developed urban cores to lightly developed rural fringes.
Some researchers question these assumptions, however,
suggesting that the urban-rural gradient approach fails to cap-
ture complexities in dynamic urbanization and its socio-
ecological effects. They argue that cities grow and operate in
non-linear patterns and that aggregated proxies for urban
drivers oversimplify anthropogenic impacts (Ramalho and
Hobbs 2012; Wandl et al. 2014). Researchers that employ
the urban-rural gradient generally accept that the approach
is a simplification that provides a useful tool for detangling
Electronic supplementary material The online version of this article
(https://doi.org/10.1007/s11252-018-0734-1) contains supplementary
material, which is available to authorized users.
* Robert J. Warren, II
hexastylis@gmail.com
1
Department of Biology, SUNY Buffalo State, 1300 Elmwood
Avenue, Buffalo, NY 14222, USA
Urban Ecosystems (2018) 21:577–583
https://doi.org/10.1007/s11252-018-0734-1
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