OOS 46-3 - Integrating network and meta-ecosystem theories to study zoogeochemistry

There is growing empirical evidence from diverse biomes demonstrating how animals affect elemental cycling at local and regional extents. Theory on the zoogeochemical impacts of animals, however, lags behind empirical progress. Developing zoogeochemical theory in parallel with empirical research is paramount to forecasting how the loss (i.e., extinction) and gain (i.e., re-introductions) of animals will cascade to influence elemental cycling. Progress is particularly needed to heed the recent calls for considering animals in nature-based carbon mitigation strategies. In this talk, we will review salient components of aspatial network theory and spatial meta-ecosystem theory that can be integrated as a foundation for zoogeochemical theory.

Our synthesis of existing theories identified three key considerations for the development of zoogeochemical theory: i) dynamic feedbacks between biotic and abiotic components are critical to predicting ecosystem elemental budgets, ii) feeding mode, body size, and movement rates are key traits driving zoogeochemistry, iii) incorporating the diverse mechanisms for animal effects on elemental cycling is essential for precise predictions. We propose a framework for aspatial trait-based network models with biotic and abiotic feedbacks as a starting point for zoogeochemical models with intermediate complexity. Such models would capture key features of ecosystems while being simple enough to be fit to data from empirical case studies. Animal effects, however, often vary across landscapes and spatially explicit models are needed to capture spatial heterogeneity in zoogeochemistry. We propose that aspatial trait-based network models can be used with spatial patch dynamics models to predict how different animals may impact spatial heterogeneity in elements at regional extents. This framework will allow for local patch dynamics to be coupled via spatial flows of matter and organisms across a landscape. We illustrate this framework with a model case study of moose (Alces alces) and snowshoe hare (Lepus americanus) effects on elemental cycling in the boreal forests of Newfoundland, Canada.

The Anthropocene is characterized by significant shifts in biodiversity in every major biome on earth. We now appreciate that these biodiversity shifts can impact ecosystem functions such as elemental cycling and the services ecosystems provide such as food production. We outline a roadmap for developing zoogeochemical theory with close integration with empirical research. Such theory is necessary to inform natural resource management for the persistence and restoration of ecosystem elemental cycling.