Department of Geosciences

Analysis of fossilized Triceratops horridus remains within the Chicxulub Event Deposit of the uppermost Hell Creek Formation, and footprints of non-avian dinosaurs and flying reptiles from the excavated paleo surface underlying the Cretaceous-Tertiary (K/T) Boundary as marked by the Iridium anomaly, is used to interpret the very last moments of the terminal Cretaceous Period on the latest paleo surface available.
The research included characterization of the Triceratops’ bone histology and taphonomy, in addition to the preservation and diversity of the footprints. The data is used to interpret a “temporal snapshot” of the last days to weeks of the Late Cretaceous, offering insight to the site`s paleoenvironment immediately prior to the K/T impact event. Data from the Triceratops histological analysis indicates the animal died in the Spring, coinciding with the end of the Cretaceous. The tracks indicate a diverse non-avian dinosaur population composed of several families and breeding age individuals.

This study investigates the spatial disparities in flood risk and social vulnerability across 66,543 census tracts in the Conterminous United States (CONUS), emphasizing urban–rural differences. Utilizing the American Community Survey (ACS) 2016–2020 data, we focused on 16 social factors representing socioeconomic status, household composition, racial and ethnic minority status, and housing and transportation access. Principal Component Analysis (PCA) reduced these variables into five principal components: Socioeconomic Disadvantage, Elderly and Disability, Housing Density and Vehicle Access, Youth and Mobile Housing, and Group Quarters and Unemployment. An additive model created a comprehensive Social Vulnerability Index (SVI). Statistical analysis, including the Mann–Whitney U test, indicated significant differences in flood risk and social vulnerability between urban and rural areas. Spatial cluster analysis using Local Indicators of Spatial Association (LISA) revealed significant high flood risk and social vulnerability clusters, particularly in urban regions along the Gulf Coast, Atlantic Seaboard, and Mississippi River. Global and local regression models, including Ordinary Least Squares (OLS) and Geographically Weighted Regression (GWR), highlighted social vulnerability’s spatial variability and localized impacts on flood risk. The results showed substantial regional disparities, with urban areas exhibiting higher flood risks and social vulnerability, especially in southeastern urban centers.

Flood events are becoming more frequent and intense as time progresses, ushering in a “new normal” for life in South Florida, a life that presumably requires flood literacy for resilience. Utilizing a 45-question digital survey, flood literacy of 600 participants from Broward, Miami-Dade, Monroe, and Palm Beach counties was assessed. Using seven indices developed for this study including residency, flood terminology literacy, flood insurance literacy, floodplain literacy, flood experience, risk communication awareness, and mitigation strategies, it was found that less than 80% of participants were flood literate, with most indicating low experience with flooding and mitigation. Interaction with risk communications and consideration of flood impacts in residency decisions were indicated as moderate. Due to inconsistencies in parts of analysis, further stratification of index topics and unification of questions types would be beneficial for future iterations of this study.

This study examines the impact of uncertainty associated with Light Detection and Ranging (LiDAR) derived Digital Elevation Models (DEMs) on flood risk mapping in the North Biscayne Bay sub-watershed. A comparison of flood extent and generation of the probability of flooding was carried out using the bathtub and probabilistic approaches respectively. The water level was computed separately for original and refined DEM using Cascade 2001 hydrological model. Using land cover based corrected DEMs reveals a 12% reduction in flooded areas in contrast to original DEM, considering uncertainties associated with land cover. Probabilistic flood modeling via Gaussian Geostatistical Simulation accounts for DEM uncertainty, yielding nuanced probability flood risk maps (0-100%). Findings emphasize DEM refinement before conducting flood mapping to address uncertainties. Future research should explore other mediums of correction incorporating effects of point density of LiDAR, methods of DEM generation, use of diverse scenarios, and kriging techniques for flood modeling and mapping while using LiDAR derived DEM.

Melaleuca quinquenervia is an Australian tree, an aggressive invader of South Florida ecosystems, and has impacted over 100,000 acres of wetlands with many documented deleterious effects on native ecosystems. Millions of dollars are spent each year on management. The most rapid and cost-effective approach to date is the delivery of broadcast aerial herbicide application via helicopter, though long-term effects of this indiscriminate approach on native vegetation communities is poorly understood. We experimentally examined the effects of broadcast herbicides on uninvaded sawgrass plots in comparison to clip treatments and controls which showed that while clipped plots quickly recovered toward pre-treatment dominance, herbicide plots remained highly dissimilar and showed little to no recruitment even after 36 weeks. We also examined untreated Melaleuca stands to assess relationships between invasion severity and canopy cover using a generalized linear model with a beta distribution. Basal area, number of stems, and the interaction between basal area and number of stems was significantly related to canopy cover. Finally, we surveyed transects through aerially-treated Melaleuca stands (7 years post-treatment) separated into zones of dense infestation, sparse infestation, and untreated marsh. We compared differences in microtopography, invasion severity, and water quality to quantify changes in the physical environment brought about by both invasion and aerial treatment relative to the surrounding marsh. Additionally, we used percent cover abundance of vascular plant species in plots to compare vegetation communities between zones.

South Florida is at the frontlines of climate change impacts. Facing increases in heat waves, flooding, and intensity of storms, climate change has direct detriments on the residents of this region. This research examines the evidence of Climate Change Anxiety (CCA) within Broward, Miami-Dade, Monroe, and Palm Beach counties. Using the CCA instrument developed by Susan Clayton and Bryan Karazsia in 2020, this study replicates analyses of variables conducted in prior research on the national level. This research found South Floridians are experiencing moderate levels of anxiety caused by climate change. Additionally, significant relationships exist between CCA and newly examined variables such as family situations, politics, and sociological perceptions. Sociological perceptions such as identities described in Dan Kahan’s Cultural Cognition Theory help us understand how having different views of society and life may alter how an individual is affected by CCA.

Forest ecosystems are critically important to biodiversity and the global carbon budget. Within forest ecosystems, dead wood has several ecological roles, including in carbon and nutrient dynamics and biodiversity conservation. However, surface fuels in forests also influence wildfire behavior and associated risks and hazards. Therefore, appropriate management of dead wood contributes directly to appropriate functioning of the forest ecosystem by conserving forest biodiversity, mitigating extreme wildfire events and pyrogenic emissions, and enhancing carbon sequestration. Using data extracted from peer-reviewed journal articles, geospatial, and field inventory data, and integrating meta-analytic, hierarchical regression, and vegetation simulation modeling approaches, this dissertation project examined the influence of dead wood on biodiversity, carbon, and wildfires in forest ecosystems.
The meta-analysis results suggest that dead wood quantity is an indicator of forest biodiversity, while dead wood types and decay stages had varied relationships with biodiversity. Generalized linear and additive mixed effects modeling of geospatial and human observed data demonstrated the predominant influences of weather conditions and moderate effects of live and dead fuels on exceptionally large wildfires’ behavior in the western United States. Consistently dominant effects of temperature on wildfire behavior highlight and emphasize the pressing need to address climate change's impact on western US forests. Lastly, vegetation and wildfire simulation modeling of forest stand inventory data and post-modeling carbon computations suggested that physical harvesting of dead wood, an approach analogous to traditional practice of firewood collection, when combined with modern mechanical fuel reduction treatments in Sierra Nevada, CA, mixed conifer forests has great potential to mitigate wildfire hazards, reduce fire emissions, and enhance carbon sequestration.

On September 28, 2022, Hurricane Ian, a large Category 4 hurricane, caused catastrophic damage and significant morphologic change along the southwest Florida barrier islands. This study evaluates the morphologic changes and sedimentological signatures of deposits resulting from Hurricane Ian through a combination of sediment cores, RTK-GPS beach profiles, and pre- and post-storm digital elevation models. During the storm, bidirectional sediment transport processes occurred along both developed and undeveloped shorelines, producing extensive washover deposits and ebb scour channels from the flood and ebb surges, respectively. Washover deposits contained interbedded sand and shell fragments with vertical grain size distributions dependent on position relative to the dune crest. Both washover deposits and ebb scour channels formed along dune crest elevational lows and were limited by dense vegetation and anthropogenic structures. Results from this study can be used to better constrain morphologic changes resulting from bidirectional sediment transport processes during large magnitude storm events.

A nearshore ridge complex (NRC) sits less than 250 m from the coast of Pompano Beach in Southeast Florida, and the varied bottom types within this complex may represent critical habitat for benthic mollusks. In order to document the diversity of mollusks within the NRC, SCUBA-based roving surveys were conducted between 2011 and 2019. Between 2021 and 2022, sediment samples were also collected from each of the bottom types to study mollusk diversity patterns. This combination of survey methods resulted in the identification of 325 species of hard-shelled mollusks, representing 103 families and 4 classes. To test for differences in community structure between bottom types, relative abundance data from the sediment samples was used for multivariate analyses including NMDS ordination, ANOSIM, and hierarchical cluster analysis. Results indicated statistically significant differences in mollusk species composition between NRC bottom types.

Gentrification describes rapid infrastructure development and investment in areas with lower income classes. It may cause potential erasure of the original neighborhood's unique culture and the displacement of residents. Due to rising sea levels and the increase in the frequency and intensity of storms, the inundation of Florida will increase as time passes. This creates an ironic relationship where historical coastal areas inhabited by an affluent population will move inland to historically lower-income populations. This thesis developed a Climate Gentrification Index (CGI) to identify areas at risk of gentrification caused by inundation of storm scenarios in Tampa City, Florida. Socioeconomic data and inundation data produced from a hydrological model were combined to define CGI and areas with high risk were mapped and discussed.