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Abstract

Understanding how and why complex systems work is vital across contexts, including ecological food webs and post-secondary education. Initially, I focus on testing how food webs change when humans modify the environment. Humans have modified the environment through land use change (i.e., forest fragmentation) and climate change. These changes can lead to alterations in ecosystem function and community composition; there is great variation in these alterations depending on context. To better understand the impact of these changes, I used a small, replicable ecosystem (artificial treeholes). First, I tested top-down controls in these ecosystems, using observational and experimental methods to examine how fragmentation of the forests that treeholes were located in altered top-down effects. While there were clear fragmentation-dependent top-down effects on the top predator, there were few fragmentation or predator driven effects on detritivores. Second, I conducted an experiment testing fragmentation-dependent bottom-up effects on the same ecosystem by placing leaf litter from different sized forests into treeholes across the fragmented landscape and then measuring leaf litter loss and community composition. I found that there was a strong effect of forest fragmentation on leaf litter loss related to the size of the forest the litter originated from. The presence and magnitude of forest size effects – and if that effect was driven by leaf litter origin – were taxa-dependent. The majority of taxa were affected by the size of the forest in which the treehole was located, not the source of leaf litter. Third, I examined how forest gaps from hurricane disturbance changed these communities by comparing leaf litter loss and community composition in hurricane-disturbed and intact forest sites. While leaf litter loss was not different between treatments, there was greater community variation in hurricane-disturbed sites. Finally, I explored how Graduate Student Teaching Assistants (GTAs) see their experience as part of their education and how they derive meaning from it using a phenomenological interview approach. Overall, GTAs see their experience as vital to their education and derive meaning through relationships with faculty and students. This dissertation underscores the importance of complexity in understanding how systems work, both in ecological and human-specific contexts.