McGill University
Ph.D. candidate
Supervisor: Fiona Soper
Martijn Slot, Smithsonian Tropical Research Institute
Start: 2023-09-03

Project

Forecasting climate change impacts on tropical nitrogen cycling: from field data to global models
It is critical to understand the effects of climate change on tropical forest ecosystems to accurately forecast global responses. Climate change is altering the frequency and severity of ecosystem stressors, specifically warming and drought. Currently, we lack understanding of how environmental conditions, specifically climate and soil, alter the flow of nitrogen (N), critical for plant growth, through tropical ecosystems. Before we can assess the impact of climate change on the N cycle, we must define how individual and interacting environmental conditions regulate N availability and loss from the ecosystem. N availability is a double-edged sword, having either a negative feedback on climate change by fueling growth and therefore carbon sequestration, or positive feedback as it is a precursor to a strong greenhouse gas, nitrous oxide (the primary loss of N from ecosystems). This project will determine if the environmental conditions of previously measured sites align with actual combinations of conditions across tropical ecosystems, utilize existing climate change experiments to collect field measurements of nitrous oxide emissions, and then use these field data to improve tropical N cycling representation in the global models used to forecast climate change. I completed a literature review synthesizing 100 years of data to define the combinations of conditions we’ve sampled to identify blind spots and to guide future data collection. How warming and drying will affect forest N cycling individually and in interaction is unclear. Their interactions could improve or worsen climate change. I will collect the first long-term tropical dataset of nitrous oxide emissions in existing warming and drying experiments, spanning multiple seasons to capture the dynamics of emissions at the Smithsonian Tropical Research Institute in Panama. Climate change experiments are logistically and financially difficult to run and maintain, and none currently consider interacting climate change stressors in the tropics. To combat this and expand temporal and spatial coverage, terrestrial biosphere models (TBMs) are our best tools to forecast climate change effects on N cycling and its influence on carbon cycling at the global scale. To test the accuracy of these models, I will leverage existing infrastructure to test two TBMs at the site level: the land components of the flagship Canadian earth system model, and the United States equivalent. I will test hypotheses about the effects of changing climate on the tropical biome and generate predictions to guide the next generation of multifactorial ecosystem experiments in the tropics.

Keywords

biogeochemistry, climate change, ecology, global change, greenhouse gas

Publications

1- Total CO2 budget estimate and degassing dynamics for an active stratovolcano: Turrialba Volcano, Costa Rica
Nelson, Kate M., Christofer Jiménez, Chad D. Deering, Maarten J. de Moor, Joshua M. Blackstock, Stephen P. Broccardo, Florian M. Schwandner, Joshua B. Fisher, Snehamoy Chatterjee, Guillermo Alvarado Induni, Alejandro Rodriguez, Doménicca Guillén Pachacama, Alexander Berne, Cecilia Prada Cordero, Paola Rivera Gonzalez, Espree Essig, Manuel E. Anderson, Carlos Hernandez
2024 Journal of Volcanology and Geothermal Research