COS 25-3 - Integrating empirical data and mathematical models to forecast the effects of multiple terrestrial disturbances on small stream ecosystem function

Abstract: Human activity has impacted ecosystems for centuries, altering important habitats and resulting in biodiversity loss, climate change, and modified global nutrient cycles. Mitigating and managing environmental change has thus become an increasingly important task, but the complexity of ecosystem dynamics makes it an ongoing challenge. Meta-ecosystem theory is a novel framework for explaining how ecosystems are connected throughout the landscape by flows of energy, matter, and organisms. Meta-ecosystem models can predict properties that arise from connections among ecosystems (i.e., productivity and ecosystem stability), but are challenging to restrict to the finite spatial and temporal scales required for real-world application. We derived a meta-ecosystem model for the island of Newfoundland, Canada to understand how disturbances in a terrestrial ecosystem impact the functioning of small streams. Our study system is undergoing rapid change with disturbances associated with moose browsing, insect outbreaks, forestry, and ATV trail development. My objectives are to 1) empirically measure the impact of terrestrial disturbances on stream function at multiple spatial extents; 2) use these field data to parameterize a terrestrial-aquatic meta-ecosystem model that considers the effects of multiple disturbances on small streams; and 3) use the meta-ecosystem model to forecast stream productivity under different disturbance scenarios. My research links in situ data collection, geospatial analysis, and mathematical modelling, creating a framework for connecting meta-ecosystem models to real landscapes. Early results from the statistical analysis of the in situ (i.e., field study in 2022) and geospatial data indicate a negative relationship between terrestrial disturbance and both invertebrate biomass and EPT index (presence of sensitive benthic invertebrate species) across all spatial extents. Trail density had a negative relationship with invertebrate biomass at the small extent (i.e., within 550m of the sampling site), and a positive relationship total suspended solids at the large extent (i.e., catchment). We are integrating these empirical results with disturbance scenarios in our meta-ecosystem model. This integration will improve our mechanistic understanding of ecosystem functioning and can inform moose and spruce budworm management on the island of Newfoundland, as well as create a framework for similar models to be used for wildlife management policies elsewhere. Including meta-ecosystem models in landscape management allows us to strike a balance between societal and ecological benefits and concerns, enabling informed decision making and adding to our understanding of the indirect effects disturbances have across space and time.