Microbes in soils break down organic material and produce CO2, a major greenhouse gas in the atmosphere responsible for global warming. In turn, rising temperatures may increase the activity of these microbes, causing more CO2 to be lost to the atmosphere. The so-called positive feedback is a daunting threat to ecosystem sustainability and human society. However, responses of microbes in soils are complex. Different microbial groups may respond differently to temperature increase through changes in growth, composition and physiology. There may also be genetic changes to these microbes, which may profoundly change the impact of microbial activities. Genetic changes in response to temperature increases have rarely been studied. In addition, soil organic carbon varies substantially in how quickly it can be decomposed by microbes as temperatures increase. Given this level of complexity, it is difficult to achieve accurate predictions of soil response to temperature change. This research will design a unique soil warming experiment to test hypotheses on microbial responses to future environmental changes. Results will add substantially to knowledge on carbon cycling and allow better forecasts of environmental changes. In addition, this project will greatly increase research capacity at an institution serving underrepresented minorities, with strong impacts on their training and retention in STEM fields.
In this project, it is hypothesized that soil warming will cause consistently more CO2 loss to the atmosphere. This is likely driven by greater microbial decomposition of recalcitrant carbon compounds in soil organic matter (SOM), supported by elevated phenolic oxidase activity and greater diversity in fungal laccase genes. To address this hypothesis, a soil warming infrastructure will be established at Tennessee State University (TSU) to collect high frequency data on soil respiration, SOM content and quality, microbial community composition, extracellular enzyme activities, and microbial genomic information for at least two years. It is further hypothesized that thermal adaptation will result in decreased carbon use efficiency (CUE) and accelerated biomass turnover (rB) of microbial communities under warming. To address this hypothesis, the streams of data collected in the experiment will be integrated with a microbial ecosystem model to estimate the temperature sensitivities of CUE and rB. These efforts will improve the mechanistic understanding of soil microbial community response to temperature change. The project results should improve the representation of microbial processes in Earth system models. By developing strong research collaborations with the University of California Irvine (UCI), a leading institution in microbial and ecological sciences, this project will enable underrepresented minorities to participate in learning state-of-the-art modeling skills, and to get hands-on experience in microbial and molecular analytical techniques.
This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.
