Study 1 (Earhart & Tarter): Describing Tropical Termite Nest Growth and Decline Patterns Using Logistic Growth Models

Describing tropical termite nest growth and decline patterns using logistic growth models Termites act as ecosystem engineers, capable of recycling most dead organic material and maintaining the flow of resources in a tropical ecosystem; this characteristic may be especially important on St. John, USVI, where the arboreal nesting termite, Nasutitermes acajutlae is the major invertebrate degrader. Our goal is to investigate nest growth, decline, and longevity on St. John, as well as to understand how biotic and abiotic factors affect changes in nest size and survival, via mathematical models. We have collected natural history data on \u3e200 N. acajutlae nests from five major habitat types (dry, mangrove, moist, sparse, wooded/wetlands) spanning the years 1998-2012. We developed an adaptive logistic model using nest volumes from these years capable of describing the patterns of nest growth and decline from year to year for each habitat. We observed that growth and decline, and general nest size patterns were typically unrelated between habitats. However, each habitat has its own typical pattern of growth and decline. Using this model, it is possible to estimate when nests first appeared and their likely longevity, enabling us to effectively determine the average nest lifespan for each habitat. In the future, we will incorporate both abiotic (i.e., ambient humidity and ambient temperature) variables, and intrinsic biotic (e.g., production of alates) to estimate their affects on nests in each habitat. This will allow us to predict the efficacy of termite degradation in tropical ecosystems in changing environmental conditions