Though it is widely held that social-ecological diversity is critical for resilience and the recovery of post-trauma urban systems, there is disagreement over issues of causes and impacts. In this paper, we present analysis and findings of the impact of trauma on patterns of social-ecological diversity in New Orleans in the years following the Hurricane Katrina disaster (August-September 2005). We first provide an overview of conceptualizations of trauma and urban ecosystem resilience, and discuss programmatic research questions and objectives. We then examine city-wide land use / land cover change, showing that flood trauma reduced landscape-level ecological diversity across New Orleans. By reconstructing archival biotic surveys of indicator organisms, we also show that many ecological communities within New Orleans experienced an acute decline, followed by recovery over time. Census-based analyses indicate that ethno-racial diversity also increased over time. Unlike pre-Katrina conditions, ethno-racial and landscape-level ecological diversity were negatively correlated after the disaster as a consequence of contrasting responses to flooding. Our analyses and findings highlight the complexity and challenges of conceptualizing, operationalizing, and measuring social-ecological diversity and related processes of resilience.