Nor Azizah Kusai
Candidature
PhD Candidate
Thesis title
Soil microbial mechanisms regulating nitrous oxide emissions under climate change
Research project
The intensification of climate extremes, characterized by rising temperatures and the increasing frequency of rainfall events, has a significant impact on nitrous oxide (N₂O) emissions, reinforcing their positive feedback on global warming. Such climate extremes will alter soil moisture and temperature, which may enhance the microbial processes responsible for N2O production. Both warming and rainfall extremes will trigger cascading effects on N2O production, via disturbance to microbial communities who are the main factor regulating N2O emissions. These perturbations will affect nitrogen (N) cycling processes such as N fixation, mineralization, nitrification, and denitrification, and ultimately lead to altered N2O emissions. However, the interactive effects that warming and rainfall extremes have on N2O emissions, and its mechanisms remain understudied as most studies focus on only one climate factor, either temperature or rainfall. Specifically, the effects of climate extremes including periodic rewetting-drying cycles and seasonal fluctuations that can lead to significant increases in fluxes driven by the dynamics of soil microbial communities and their activities, have not been adequately studied.
This research aims to understand the processes and mechanisms of N cycling and N2O production under climate extremes (elevated temperature and extreme rainfall) in the experimental pasture ecosystems. This research employs continuous monitoring of N₂O emissions using automated long-term chambers, quantification of N-cycling functional genes through qPCR, and soil microbial community analysis via a metagenomic approach. Additionally, this research will assess the efficacy of nitrification inhibitors (NIs) in mitigating N losses in pastures under projected future climate extremes.
This research will improve our understanding of the mechanisms and processes controlling N2O emissions driven by the complex interactions of soil biogeochemical dynamics in pasture ecosystems under future climate scenarios. The findings are expected to improve climate model predictions and provide practical insights for mitigating N₂O emissions.
Supervisor
Associate Professor Catriona Macdonald
