Precipitation Change, Switchgrass Biomass, and Greenhouse Gas Emission

Faculty #39
Discipline: Ecology, Environmental & Earth Sciences
Subcategory: STEM Research
- Tennessee State University
Co-Author(s): Qi Deng, Sadiye Aras, Chih-Li Yu, Kathrine Miller, E. Kudjo Dzantor , Tennessee State University, Nashville, TN; Philip A. Fay , United State Department of Agriculture, Temple, TX ; Weijun Shen , South China Botanical Garden, the Chinese Academy of Sciences, Guangzhou, China ; Yiqi Luo , Northern Arizona University, Flagstaff, AZ

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Switchgrass (Panicum virgatum L.) is widely selected as a model feedstock for sustainable replacement of fossil fuels and climate change mitigation. However, how climate changes, such as altered precipitation, will influence switchgrass growth and soil carbon storage potential have not been well investigated. We conducted two precipitation manipulation experiments with five treatments: -50%, -33%, +0%, +33%, and +50% of ambient precipitation, with an ‘Alamo’ switchgrass in Nashville, TN. Results showed that the wet (+33%, and +50%) treatments had little effects on aboveground biomass and leaf gas exchange compared to the ambient precipitation treatment, regardless of fertilization or not. The -33% treatment did not change aboveground biomass and leaf photosynthesis, but significantly decreased transpiration and enhanced water use efficiency. Only the -50% treatment significantly decreased plant biomass and leaf area index, without changing leaf photosynthesis. Soil CO2 emission generally decreased under the drought treatments and increased under the wet treatments, while there was no significant difference between the two drought treatments or between the two wet treatments. Our results demonstrate that switchgrass biomass responded in a single negative asymmetry model to precipitation changes, but soil CO2 emission responded strongly to precipitation changes in an ?S? curve model. The contrasting models for switchgrass biomass and soil respiration in response to precipitation indicate that extreme wet or dry conditions may shift ecosystem from carbon accumulation toward debt, and in turn provide government and policy makers with useful information for sustainable management of switchgrass.

Funder Acknowledgement(s): This study was financially supported by the NSF HBCU-UP, NSF IUSE, USDA CBG, and USDA Evans-Allen programs

Faculty Advisor: None Listed,