Our Urban Homogenization group has a new paper out in the Proceedings of the National Academy of Sciences. Led by Colin Polsky at Clark University, the paper shows that lawn care practices vary both among cities and among different life stages, development densities, and socio-economic groups within cities. The major conceptual contributions of the paper are to introduce the idea of scale to our previous work on homogenization, and to demonstrate that lawn care practices may be very heterogeneous, even if the biophysical structure of residential landscapes is homogenized by urbanization.
We have two new papers that just came out as part of a special issue of Frontiers in Ecology and the Environment on continental scale ecology.
The first paper (Heffernan et al. 2014; Macrosystems Ecology: Understanding Ecological Pattern and Processes at Continental Scales) proposes a framework for incorporating a systems perspective more completely into the study of broad-scale ecological phenomena. This means thinking about processes like feedbacks between vegetation and climate, long-distance connections between ecosystems, and ways in which broad- and fine-scale phenomena influence one another. We think that this broad scale systems perspective ('Macrosystems Ecology') is going to be essential for predicting the effects of many different anthropogenic changes that have causes and consequences at the scale of whole regions and continents. One challenge in writing this paper is that ecologists and others have been thinking about regions and continents for a long time, in sub-disciplines like biogeography and related fields like climate science. We argue that two things are changing - 1) across these fields, we are incorporating more and more process into that understanding (which is made easier through data sets that have a fine resolution but cover broad extents); and 2) that we are able to make more and more connections across different types of phenomena (e.g., linking climate change, population genetics, and habitat loss; or understanding the diverse ecological consequences of bark beetle outbreaks). We also deal with the question of 'What is distinct about macrosystems?' Again, part of the challenge is that many ecological theories are supposed to apply to all scales, so lots of characteristics of macrosystems are likely to fit within such theory. One the other hand, some may not; one way (the only way?) to figure out whether macrosystems are distinct is to study regions and continents as systems through the lens of such theory. There is already some neat work that tries to do this, and hopefully lots more on the way!
The second paper (Groffman et al. 2014; Ecological homogenization of urban USA) is an overview of our 'Urban Homogenization' project, and presents some of the preliminary data that led us to this work in the first place. This is the project that includes Meredith Steele's work on surface water features in cities.
Meredith Steele's paper (with a long list of co-authors) on the surface water characteristics of US cities has been accepted at Ecosystems! Congratulations Meredith!
Abstract: Earth’s surface is rapidly urbanizing, resulting in dramatic changes in the abundance, distribution and character of surface water features in urban landscapes. However, the scope and consequences of surface water redistribution at broad spatial scales are not well understood. We hypothesized that urbanization will lead to convergent surface water abundance and distribution: in other words, cities will gain or lose water such that they become more similar to each other than are their surrounding natural landscapes. Using a database of more than 1 million water bodies and 1 million km of streams, we compared the surface water of 100 US cities with their surrounding undeveloped land. We evaluated differences in areal (AWB) and numeric densities (NWB) of water bodies (lakes, wetlands, etc.), the morphological characteristics of water bodies (size), and the density (DC ) of surface flow channels (i.e. streams and rivers). The variance of urban AWB, NWB, and DC across the 100 MSAs decreased, by 89%, 25%, and 71% respectively, compared to undeveloped land. These data show that many cities are surface-water poor relative to undeveloped land; however, in drier landscapes urbanization increases the occurrence of surface water. This convergence pattern strengthened with development intensity, such that high intensity urban development had an areal water body density 98% less than undeveloped lands. Urbanization appears to drive the convergence of hydrological features across the US, such that surface water distributions of cities are more similar to each other than to their surrounding landscapes.
Two pieces have just been published about our Urban Homogenization work. The first, by science reporter Maggie Koerth-Baker, provides a layperson's overview of the urban homogenization hypothesis and some of the patterns that initially motivated our proposal. It will be published on Sunday in the New York Times magazine, and is online here. The second piece is an article written by Laura Ogden, an anthropologist and one of our collaborators on the project. Laura's piece addresses the peculiar social and ecological geography of south Florida, and the differences between front yards and back yards. The article was written for Miami Rail, a local alternative newspaper, but you can read it on the Art Practical website here.
This is the homepage of the Heffernan Lab at Duke University. Here you can find all sorts of information about our research, teaching, and outreach. If you have any questions, contact Dr. Heffernan.
Dr. Jim Heffernan
I am an Assistant Professor in the Nicholas School of the Environment at Duke University. My research is focused on the causes and consequences of major changes in ecosystem structure, mostly in streams and wetlands.
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