Date of Graduation

5-2017

Document Type

Thesis

Degree Name

Bachelor of Science in Chemical Engineering

Degree Level

Undergraduate

Department

Chemical Engineering

Advisor/Mentor

Thoma, Greg

Committee Member/Reader

Hestekin, Jamie

Abstract

Climate change is a result of greenhouse gases released into the atmosphere. These changes are expected to cause extreme weather conditions, including severe storms. Large amounts of rain will fall in shorter periods of time, leading to heavy runoff, and increasing the severity of drought conditions within the soil (Zeglin et al. 2013).

Native grasslands occupy almost a quarter of the earth’s land surface and are valuable ecological resources. They contain soils with high concentrations of organic matter and play a key role in mitigating greenhouse gas emissions through carbon sequestration. There are a variety of grassland management techniques including annual burning, patch burning, and cattle grazing. These management techniques can be beneficial for ecosystems, but can also alter soil compositions (Jerome et al. 2014). Microbial communities in the soil influence many ecosystem processes such as nutrient acquisition, carbon and nitrogen cycling, and soil formation (Heijden et al. 2008). Changes in precipitation patterns can effect microbes in these grasslands by causing shifts in community composition, and changes in nutrient cycling and decomposition processes. Many microbial activities can be directly correlated with water availability, and drought conditions may be detrimental to these grazed grassland ecosystems (Gray et al. 2011). Summer months and differences in time lead to changes in temperatures and rainfall patters, similarly having the potential to alter activity and structure of microbial communities.

This study was conducted at the Konza Prairie Biological Station in eastern Kansas, USA. Soil samples were collected to compare June versus July and moist versus dry treatments. Findings from this study concluded that seasonal changes through June and July alter microbial communities in Konza Prairie soil. Total PLFA concentrations significantly increased, with the largest increase occurring in fungi. This change caused a decrease in relative abundance of gram positive and gram negative bacteria, and also an increase in the ratio of fungi to bacteria. Drought conditions caused no significant change in microbial communities, suggesting the microbes in the soil have a high tolerance for lack of moisture.

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