Nitrogen-fixing trees are an important nitrogen source, driving carbon dioxide (CO2) sequestration in plant biomass. However, nitrogen-fixing trees also stimulate significant nitrous oxide (N2O) emissions from soils. I am interested in the radiative offset of CO2 sequestration by N2O emissions driven by nitrogen-fixing trees. I am addressing this question using both a theoretical approach (see  below) as well as an empirical approach (for which I am conducting field work at Black Rock Forest, NY as part of a project lead by Duncan Menge, Jen Funk, Amy Wolf and Steve Perakis).
I am interested in how biological nitrogen fixation is represented in terrestrial biosphere models, specifically in the Geophysical Fluid Dynamics Laboratory's (GFDL) Land Model 4 (LM4.1). I am developing a representation of biological nitrogen fixation in LM4.1, which I will use to study the radiative balance of CO2 sequestration in plant biomass and soil N2O emissions driven by biological nitrogen fixation, and the degree to which these will be influenced by global change. I am working with Steve Pacala, Sergey Malyshev, Isabel Martínez Cano, and Elena Shevliakova on this project.
1. Nitrogen-fixing trees could exacerbate climate change under elevated nitrogen deposition. Sian Kou-Giesbrecht and Duncan Menge. Nature Communications. 2019.
2. Testing for a whole-organism trade-off between natural and sexual selection; are the male guppies preferred by females more likely to be eaten by predators? José Jonathas P. R. de Lira, Felipe Peréz-Jvostov, Kiyoko M. Gotanda, Sian Kou-Giesbrecht, Sarah K Pease, Marlee Jackson, Shaffiq Jersch & Andrew P. Hendry. Evolutionary Ecology Research. 2019.
3. Asian Americans: The Forgotten Minority in Ecology. Sian Kou-Giesbrecht. The Bulletin of the Ecological Society of America. 2020.
Measuring trees at Black Rock Forest, NY