Post disaster greening may reflect a failure of public policy, not a triumph of nature

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Advocates for urban nature often view vegetation growth in the wake of natural disaster or deindustrialization through a romanticized lens, as nature “reclaiming” the city. But the truth is more complex, researchers reported last month in the journal Ecosphere.

They analyzed patterns of plant growth across eight neighborhoods in the New Orleans area after Hurricane Katrina struck the city on August 29, 2005. The hurricane’s rainfall and storm surge resulted in flooding and levee failure that led to over 1,500 deaths and $125 billion in damages. Some areas were underwater for three months; after the waters receded, scores of damaged homes and businesses were demolished, and many owners abandoned their land as they left the city.

Few studies have looked at how natural disasters influence urban plant communities. The new research shows that patterns of vegetation in New Orleans today don’t reflect the direct effects of Hurricane Katrina but rather landscape management policies in response to the storm.

Those policies are shaped by – and reinforce – long-standing economic and racial disparities in the city. So in poor neighborhoods with a high proportion of Black residents, New Orleans’ post-Katrina greening reflects a failure of public policy, not a triumph of nature, the researchers argue.

They analyzed vegetation cover in aerial photographs of New Orleans taken before the storm in January 2004, during the immediate aftermath in October 2005, and after some years of recovery in October 2013. They also inventoried trees, shrubs, and herbaceous plants in 180 400-square-meter plots across the city. Finally, they used government data to link vegetation patterns to socioeconomic conditions and land abandonment in the wake of the storm.

As expected, the degree of disturbance by Katrina – the difference between the January 2004 and October 2005 pictures – was greatest in the most low-lying neighborhoods, Lakeview and Gentilly, and those closest to the levee breaches, the Lower 9th Ward and St. Bernard Parish.

But the largest expansion of plant cover, as seen in the October 2013 pictures, took place in less affluent neighborhoods with high rates of home demolition, land abandonment, and state ownership of land after Katrina: Upper 9th Ward, Lower 9th Ward, and St. Bernard Parish. That finding fits the narrative of nature reclaiming the city, but with a twist: the reclamation isn’t driven just by physical events but also by socioeconomic disparities.

The nature of the vegetation also differs across neighborhoods. Regardless of elevation, New Orleans’ more affluent neighborhoods with a higher proportion of White residents tend to have more trees, ornamental shrubs, and lawn. Poorer neighborhoods with more Black residents tend to have few trees, lots of invasive shrubs, and unmaintained grass and weeds.

Unmaintained, weedy patches in poorer, Black neighborhoods reflect the larger number of abandoned parcels and lack of housing recovery in these areas. Moreover, the overgrown vegetation tends to perpetuate these problems. Although messy vegetation on vacant lots can have ecological benefits, such as cooling the surrounding area and providing resources for songbirds, it also serves as habitat for pests like rats and mosquitoes, attracts illegal dumping, and reduces safety, especially for women and especially at night. Such vegetation can be a “green blight” that further harms the recovery prospects of disadvantaged areas, the researchers say.

However, land management by local authorities can alter these trajectories. The Lower 9th Ward and parts of adjacent St. Bernard Parish, which is outside the city limits, both experienced similar effects of levee failure and flooding during Katrina, and land abandonment and population loss afterwards. But authorities in St. Bernard Parish took a more hands-on approach to abandoned lands, creating broad, park-like swathes of grass and keeping weeds and invasives in check. In New Orleans, city work crews only maintain publicly owned vacant lots, resulting in a patchwork of tidy and weedy parcels in the Lower 9th Ward. (In part, the city’s hesitancy reflects controversy over post-Katrina redevelopment and recovery programs in the Lower 9th and elsewhere, the researchers note.)

The City of New Orleans is now taking steps to address these problems through better maintenance and creating “green infrastructure” on abandoned lands. More broadly, this study of the city’s post-Katrina experience offers lessons for other cities emerging from natural disasters. “Our findings suggest that like more traditional recovery strategies (e.g., restoration of public utilities and other services), proactive landscape management is critical for anchoring and sustaining neighborhood recovery following catastrophic disasters,” the researchers write. “Placing a high priority on vegetation maintenance following a major humanitarian disaster may seem misguided, but our findings indicate that early intervention and maintenance by public agencies can deliver long-term benefits for recovering communities.”

Source: Lewis JA et al. “Socioecological disparities in New Orleans following Hurricane Katrina.” Ecosphere2017

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