I am a restoration ecologist investigating how human infrastructure and landscape modification shape native plant and animal communities. My work uses field-collected data across multiple systems and applies modern statistical tools to allow us to make inferences about the direct and indirect effects humans have on biodiversity amd how to restore these ecosystems. Below I outline two central projects that have guided my career thus far; first the NAVIDIV project, and second research from my PhD.
NAVIDIV: Inland navigation infrastructures and biodiversity: impacts and opportunities for waterwayscape management
Inland aquatic navigation is among the most promising low-carbon transport alternatives and has become increasingly important in recent years. However, it is important we find a balance between the need to develop infrastructure to support this green form of transit with the affects this has on biodiversity and ecological resilience. The central question guiding this project is: What are the effects of inland aquatic navigation on biodiveristy, and how do we mitigate them?
Freshwater ecosystems, rich with biodiversity, provide vital ecosystem services globally. However; these ecosystems are critically threathened. Four central treats to these systems are habitat degredation, loss of connectivity, flow modifications, and the indtroduction of invasive species. Infrastructure to support inland aquatic navigation and shipping have the ability to increase or decrease these issues, depending on the context. The NAVIDIV project utilizes dozens of large river datasets with fine spatial-temporal biodiversity data to investigate the mechanisms underlying the relationships between biodiversity and inland aquatic infrastructure.
Additionally, our team is conducting both meta-analyses and qualitative reviews to determine the efficacy of restoration stradegies applied in large rivers to mitigate the effects of navigation. This has involved extensive literature searches and collaborations with restoration/waterway management practitioners.
Restoring plant-pollinator interactions in urban ecosystems
Grassland habitats are a novel landscape in the state of Kentucky that can provide vital habitat for a diverse group of species. Pollinators and their floral resources are important functional groups in these grasslands and my research focuses on the local and landscape level factors that influence these groups of species. By using a combination of approaches, my PhD focused on the restoration of pollinator communities in grasslands globally, and how landscape context may influence the success of these grassland restorations. I have investigated how restroation parameters influence plant and pollinator success in restorations, my monitoring floral production and phenology, seed set, pollinator visitation rates and bee fecundity. I have worked closely with restoration practitioners and land owners to identify the needs in their grasslands to support diverse, native plant and animal communities.
Floral Phenology
Increasing temperatures and changing moisture regimes are known to cause shifts in floral phenology. These phenological shifts have been extensively studied in montane regions and using experimental tools. My research investigated how floral phenology is influenced by urbanization and local habitat characteristics. Louisville, KY is one of the strongest urban heat islands in the US, with summertime highs as much as 3-5°C warmer in urban areas than in surrounding rural areas. By surveying floral communities across an urbanization gradient I was able to model how species shifted their phenologies in urban vs. rural habitat patches.
Solitary Bee Demographics
Several recent studies have found solitary cavity-nesting bees increase along an urbanization gradient, while most other bees decrease. My work investigated the to mechanisms driving this increase, by looking at bee demographics. This work was published in Urban Ecosystems in 2020, titled Reproductive patterns of solitary cavity-nesting bees responsive to both local and landscape factors.
Aaron Sexton 