urban sprawl

Thoughtful conversation about urban and metropolitan policy by urbanexus

METRO - 2009-07-27 - Nation's Cities WeeklyThere has been little discussion of urban and metropolitan policy since the White House Urban and Metropolitan Policy Roundtable on July 13, 2009.  This event may be remembered more for the crashing teleprompter than anything else (see crashing teleprompter event).  Since then, Bill Barnes, Director for Emerging Issues at the National League of Cities wrote a piece for Nation's Cities Weekly entitled Obama Urban Policy Ideas Likely to Have Consequences that offers a somewhat optimistic perspective on the Obama Administration's evolving approach to this topic.  As Mr. Barnes suggests " . . . thoughtful conversations about where we are headed are surely warranted."

Auto ownership not a major cause of urban sprawl by urbanexus

A study by Rob Wassmer, a Sacramento State University professor of public policy concludes that reduced auto use has very little effect on suburbanization or urban sprawl. Wassmer conducted a statistical analysis and concluded that a 10 percent reduction in households owning one or more cars would reduce the geographical size of an urban area by only 0.5 percent, and increase population density by only 0.7 percent. Those impacts are far smaller than those produced by other factors that create sprawl.

According to Professor Wassmer, “Natural Evolution” and “Flight from Blight” play much greater roles in generating sprawl. The concept of natural evolution is based on the idea that the older the housing stock is, the less likely households are to choose a location because households tend to prefer newer housing and most affordable new housing is built in suburban locations. Flight from blight is people dispersing to new neighborhoods on the metropolitan fringe to escape the real and/or perceived blight of the central places in urban areas.

A reduction in per capita income, an increase in the percentage of wealthy households, and a reduction in the percent of an urban area’s central places that are poor, all have demonstrably greater effects on controlling sprawl than reduced automobile use, Wasserman concluded, stating, “Land use is largely the cause of auto use, not the other way around."


Urban sprawl not as harmful to wildlife as previously thought? by urbanexus

Barn Owl in flight

On December 20, 2006, the online science journal PLoS One posted an article entitled "Depauperate Avifauna in Plantations Compared to Forests and Exurban Areas"[i]  The three authors are David G. Haskell and Jonathan P. Evans, who are affiliated with the Landscape Analysis Lab at the University of the South in Sewanee TN, USA, and  Neil W. Pelkey who is  an environmental science professor at Juniata College in Huntington, PA, USA. 

Using field surveys and digital maps of habitat, the authors compared the diversity of bird populations in natural forests, tree plantations and "exurban" (urban sprawl) areas along the Cumberland Plateau in Tennessee. They found that tree plantations had substantially less bird population diversity than did native forests and exurban areas. In some cases, exurban areas had more diversity than did the native forests.  “These findings suggest that urban sprawl is not all bad for wildlife,” Haskell says. “This turns conventional wisdom about wildlife conservation on its head.”

For years scientists have been concerned with the loss of biodiversity resulting from worldwide deforestation. Governments and private organizations have implemented conservation programs that discourage sprawl and promote tree plantations to replace deforested areas.  “Scientists had assumed that tree plantations were preferable to exurban areas for wildlife conservation,” Haskell says. “This study firmly refutes this assumption, and has important implications for government policies, many of which subsidize plantations and penalize sprawl in the name of wildlife conservation.”

For estimates of forest cover, the U.S. government classifies forest converted to tree plantation as “no loss of forest”, and classifies wooded areas where houses have been built as “loss of forest.”  “Yet our data show that plantations have much lower levels of biodiversity than do native forests and that exurban areas can retain much of the biodiversity of native forests,” the researchers write. “Therefore, current methods of accounting for forests give potentially misleading results for biodiversity analyses.” 

[i]The article can be found at:http://www.plosone.org/article/fetchArticle.action?articleURI=info%3Adoi%2F10.1371%2Fjournal.pone.0000063#aff1