New Orleans greenery post-Katrina reflects social demographics more than hurricane impact

September 15, 2017

Popular portrayals of "nature reclaiming civilization" in flood-damaged New Orleans, Louisianna, neighborhoods romanticize an urban ecology shaped by policy-driven socioecological disparities in redevelopment investment, ecologists argue in a new paper in the Ecological Society of America's open access journal Ecosphere.

"Observers can be taken in by the post-apocalyptic image that some flood-damaged neighborhoods present over a decade after Katrina. It stimulates the imagination. But local people see it as a failure of public policy and a social problem," said lead author Joshua Lewis, a research professor at the ByWater Institute at Tulane University and the Stockholm Resilience Centre at Stockholm University. "For a community that has had thousands of people come back and struggle to rebuild, to reopen schools and churches, it's frustrating to see their neighborhoods portrayed as disintegrating or losing ground to nature."

In a study of plant life across New Orleans post-Hurricane Katrina, the researchers were surprised to find that demographic factors of wealth, race, housing recovery, and land abandonment were better predictors of vegetation patterns than the degree of intensity of flooding and wind during the 2005 storm.

"A whole range of neighborhoods and demographics were hit by Katrina. They don't all have equal access to private capital and ability to navigate housing recovery programs, and that is what we see driving the type of vegetation emerging on these abandoned properties," said Lewis.

In the wake of Katrina, many of New Orleans' damaged properties were never rebuilt. Though city and state agencies maintain some abandoned lots as close-clipped lawns, other lots have grown thickets of mostly non-native, opportunistic, or invasive species. The ecological utility of these unplanned green spaces has been noted. Cooling green canopies absorb stormwater and succor songbirds, for example.

But abandoned land may also provide habitat for rats and mosquitoes, and the diseases they carry. These urban jungles can become dumping grounds for junk, harbor invasive species, and present a safety risk, especially for women. The social stigma of unmanaged "green blight" can depress redevelopment and thwart efforts to raise neighborhood prosperity and attract investment.

"New Orleans is a pretty heavily forested city, but the parks and managed green space aren't evenly distributed. The neighborhoods we're talking about had relatively low forest cover before Katrina. In hurricane-hit neighborhoods, we now have green space, but it's space that causes more problems than benefits for the people who live there," Lewis said.

Lewis and colleagues examined eight neighborhoods, representing a cross-section of demographics and flooding severity, to learn how the current plant life of post-Katrina New Orleans reflects the flooding during the hurricane and post-disaster management. They looked at the age and size of trees and other plants, recording the composition of species at sample sites, conducting interviews, and developing a social database from census data and other metrics. From this data, they assessed the influence of the city's physical and social geography on regrowth.

Neighborhoods with unmanaged growth do not necessarily have more trees, Lewis said, but they do have a lot of opportunistic and invasive trees and shrubs. The authors noted a striking contrast between the unmanaged plant pioneers dominating lots in the Lower 9th Ward and the cultivated landscape of neighboring St. Bernard Parish. Lawns, ornamental shrubs, and hurricane-resilient native trees are concentrated in wealthier, predominantly white, neighborhoods. Property that has grown wild, but remains privately owned, presents a legal problem for public agencies, which may not have permission to enter and  remove the overgrowth.

"Some municipalities have figured out ways to maintain these lots, regardless of who owns them," said Lewis, noting that neighborhoods may have different mindsets around government intervention, and political tensions over land management are perennial.

Lewis believes there are ways to transition some neglected lots into stormwater parks, utilizing them for green infrastructure interventions. But accomplishing that will require better knowledge of New Orleans' specific conditions, political will, and buy-in from skeptical residents who have seen past promises for green infrastructure projects unfulfilled, or worse, seen as an attempt at displacement of residents or neighborhood gentrification. . He also had a cautionary note for scientists conducting research in in cities that have endured environmental tragedies.

"Going in with the idea that the hurricane has created a clean slate for ecology--in an urban setting, that is not the way to approach your research. Urban ecosystems are embedded in sociopolitical dynamics that shape the current conditions, and will continue to do so going forward," he said.

Once emergent forests are established, mitigation requires cutting everything and replanting with native hardwoods and other native vegetation. Investments are being made, but biologists are several years away from figuring out how to make interventions that are affordable and easily maintained, Lewis said.

"Management and maintenance is the key problem. That's what we need to sort out here in New Orleans," Lewis said.
Journal Article:

Socioecological disparities in New Orleans following Hurricane Katrina. (2017) Lewis, J. A., W. C. Zipperer, H. Ernstson, B. Bernik, R. Hazen, T. Elmqvist, and M. J. Blum. Ecosphere 8(9):e01922. 10.1002/ecs2.1922. Open Access.



Joshua A. Lewis: ByWater Institute at Tulane University, New Orleans, Louisiana, USA; and the Stockholm Resilience Centre at Stockholm University, Kräftriket, Stockholm, Sweden
Wayne C. Zipperer: USDA Forest Service, Gainesville, Florida
Henrik Ernstson: KTH Environmental Humanities Laboratory, KTH Royal Institute of Technology, Stockholm, Sweden; Department of Geography, School of Environment, Education and Development, University of Manchester, Manchester, UK
Brittany Bernik: Tulane-Xavier Center for Bioenvironmental Research, Tulane University, New Orleans, Louisiana, USA; and Department of Ecology & Evolutionary Biology, Tulane University, New Orleans, Louisiana, USA
Rebecca Hazen: Department of Ecology & Evolutionary Biology, Tulane University, New Orleans, Louisiana, USA
Thomas Elmqvist: Stockholm Resilience Centre, Stockholm University, Kräftriket, Stockholm, Sweden
Michael J. Blum: Tulane-Xavier Center for Bioenvironmental Research, Tulane University, New Orleans, Louisiana, USA; and Department of Ecology & Evolutionary Biology, Tulane University, New Orleans, Louisiana, USA
The Ecological Society of America, founded in 1915, is the world's largest community of professional ecologists and a trusted source of ecological knowledge, committed to advancing the understanding of life on Earth. The 9,000 member Society publishes five journals and a membership bulletin and broadly shares ecological information through policy, media outreach, and education initiatives. The Society's Annual Meeting attracts 4,000 attendees and features the most recent advances in ecological science. Visit the ESA website at

Ecological Society of America

Related Invasive Species Articles from Brightsurf:

The invasive species that Europe needs to erradicate most urgently are identified
An international research team analyzed the risk impact and the effectiveness of possible erradication strategies for invasive species already in the region as well as those that have yet to arrive

Crayfish 'trapping' fails to control invasive species
Despite being championed by a host of celebrity chefs, crayfish 'trapping' is not helping to control invasive American signal crayfish, according to new research by UCL and King's College London.

Climate change is impacting the spread of invasive animal species
What factors influence the spread of invasive animal species in our oceans?

Invasive alien species may soon cause dramatic global biodiversity loss
An increase of 20 to 30 per cent of invasive non-native (alien) species would lead to dramatic future biodiversity loss worldwide.

Protected areas worldwide at risk of invasive species
Protected areas across the globe are effectively keeping invasive animals at bay, but the large majority of them are at risk of invasions, finds a involving UCL and led by the Chinese Academy of Science, in a study published in Nature Communications.

Charismatic invasive species have an easier time settling into new habitats
An international study, in which the University of Cordoba participated, assessed the influence of charisma in the handling of invasive species and concluded that the perception people have of them can hinder our control over these species and condition their spread

Invasive species with charisma have it easier
It's the outside that counts: Their charisma has an impact on the introduction and image of alien species and can even hinder their control.

Invasive species that threaten biodiversity on the Antarctic Peninsula are identified
Mediterranean mussels, seaweed and some species of land plants and invertebrates are among the 13 species that are most likely to damage the ecosystems on the Antarctic Peninsula.

Research networks can help BRICS countries combat invasive species
BRICS countries need more networks of researchers dedicated to invasion science if they wish to curb the spread of invasive species within and outside of their borders.

Look out, invasive species: The robots are coming
Researchers published the first experiments to gauge whether biomimetic robotic fish can induce fear-related changes in mosquitofish, aiming to discover whether the highly invasive species might be controlled without toxicants or trapping methods harmful to wildlife.

Read More: Invasive Species News and Invasive Species Current Events is a participant in the Amazon Services LLC Associates Program, an affiliate advertising program designed to provide a means for sites to earn advertising fees by advertising and linking to