This interdisciplinary research project focuses on ecological and socioeconomic processes following the catastrophic flooding in New Orleans associated with Hurricane Katrina in August 2005. Urban areas that have experienced a traumatic event can be highly tractable systems for studying potential parallels between ecological and socioeconomic systems as well as feedbacks among them. With acute trauma resulting in an initial state change, the assembly and reassembly of proximate or coincident urban ecological and human communities can be a coupled dynamic, where outcomes are contingent on responses to common forcing factors or interactions arising from management interventions.

The catastrophic flooding of New Orleans following Hurricane Katrina resulted in a natural laboratory for investigating assembly and reassembly of coupled natural and human systems. We aim to determine the extent to which ecological and socioeconomic diversity exhibited parallel responses to Katrina-related flooding. We also are examining how interventions executed as public health measures shaped relationships and interactions between ecological and socioeconomic diversity. We are conducting geographic information system-based analyses of landscape heterogeneity and socioeconomic variation before and after Hurricane Katrina as well as plot-based inventories of post-Katrina plant communities accounting for flooding and socioeconomic stratification. We are also examining the ecology and demography of Norway rats (Rattus norvegicus), a habitat-dependent primary reservoir of zoonotic pathogens, in order to understand human health outcomes of flooding. This facet of the project involves a trap-based census; population genetic analysis of abundance and dispersal, and histological analysis of pathogen prevalence. Mail surveys and in-person interviews of households proximate to plant inventory and trapping sites as well as households in four neighborhoods having different income and ethnicity characteristics are being administered to determine how perceptions of risk compare to physical measures of exposure risk across the city. Information gained from these studies are being integrated into a spatially explicit predictive model of Norway rat demography to assess ecological and human-health outcomes of alternative control scenarios reflecting habitat suitability, movement, and risk perceptions.

Trauma can have enduring consequences on environments and societies. Understanding the interplay between ecological and human communities will better prepare societies to anticipate and manage trauma inflicted by catastrophic events. This project is intended to help catalyze conceptual unification of disparate fields of research on the composition, assembly, and structure of communities, and it will generate new information and insights needed to foster and inform societal action at a time when unprecedented resources are being invested to rebuild New Orleans. By involving community partners, cross-university academic and public outreach programs are being coordinated to provide opportunities to promote awareness of trauma, diversity, and public health across stakeholder and underrepresented groups in the city. With urbanization placing an increasingly greater proportion of the global population at risk because of catastrophic events, we expect that lessons about the traumas experienced by New Orleans will provide new knowledge of scholarly and practical value to residents and decision makers in communities around the world.

This project is supported by the NSF Dynamics of Coupled Natural and Human Systems (CNH) Program. 

Project Overview 

Urbanization is placing the global population at risk of experiencing a major trauma. Since 1960, there has been a four-fold increase in the frequency of traumatic events affecting at least one million people (Kasperson et al. 2005). This trend largely reflects growing populations and increasing concentrations of property in coastal cities (e.g., New Orleans, New York, Shanghai) that are more susceptible to weather-related events (Cutter and Emrich 2005).

Today more people are living in urban centers than anywhere else on Earth. Considering the potential vulnerability of many urban centers to trauma, it has become increasingly important understand how these systems respond to catastrophe. However, human systems and natural systems cannot be studied in isolation. Rather multi-disciplinary approaches are needed to understand the complex relationships and feedbacks between social diversity and ecological diversity that occur in response to trauma.

By creating a multi-disciplinary team of ecologists, geographers, and sociologists, we aim to elucidate the relationships between ecological diversity and social diversity in response to traumatic events. We are using a variety of methods, from human surveys to vegetation surveys and population genetic techniques to clarify the feedbacks and relationships between human and natural systems.

Forest, Plant Diversity and Land Use

We will estimate landscape-level and fine-scale plant diversity in New Orleans by inventorying vegetation and microhabitat conditions, building from an existing network of 300 study plots (300-400 m2) that were established and surveyed in 2010 through a partnership between Tulane and the US Forest Service. The study plots are randomly distributed across the urban core of the city at a density of one per km2 and are located on both public and private space.

Quantitative modeling

Building on a recently completed NSF-funded study of post-trauma New Orleans (the New Orleans ULTRA-X study), we will estimate rates and trajectories of post-trauma socioeconomic and landscape change during the study period. The New Orleans ULTRA-X work focused on reconstructing socioeconomic characteristics and landscape heterogeneity of the cityscape before (2000-2001) and after (2008- 2010) Hurricane Katrina.

We also will develop new metrics of post-Katrina socioeconomic and landscape change. Socioeconomic data for the study period will be obtained from city, regional, state and federal entities for all available years. Landscape data will be obtained from classification of high-resolution (e.g., Ikonos) satellite imagery obtained for each year of the study period.

Rodents and rodent-borne pathogens 

We will characterize the distribution, abundance, and life-history traits of rat populations through a field-based approach. Exhaustive removal trapping will be conducted at 70 study plots drawn from the city-wide network of 300 plots described above. 

Genetic methods will be used to evaluate rat population structure, dispersal, and effective
population size. This will enable us to infer population responses to flooding and enable us to parameterize a metapopulation model of post-Katrina landscape occupancy and movement.

Socioecology of risk and risk perception 

We will assess whether perceptions of flood risk and disease risk vary according to individual and neighborhood-level ecological characteristics and social-ecological conditions by implementing multi-scale surveys and interviews that will query households on their experiences with past storms and flooding, as well as expectations and concerns regarding threats to safety, security, and well-being. The surveys and interviews also will provide individual-level data on demographics and social status (e.g., age, gender, education level, economic status) to complement block-level GIS data (as described above). The proposed surveys and interviews will be conducted each year of the project to assess shifts in risk perceptions over time.

We will implement a city-wide survey of households corresponding to the landscape-level network of 300 plots where vegetation surveys and rodent trapping will be completed (as described above). A large proportion (~60-75%) of the study plots are located within residential lots, which affords opportunities to link ecological and block-level socio-demographic data with individual survey responses. We will conduct in-person interviews concurrently with either vegetation surveys or rodent-trapping.