Isabel Ross

Green Infrastructure Impacts on Carbon Cycling: Evaluating Changes in Soil Microbial Composition and Function

Isabel Ross, Cienega High School, High School Student

This project aimed to identify how the implementation of green infrastructure (GI) water harvesting systems impacts the carbon cycle by studying shifts in microbial composition and function. To conduct this study, we created a GI system in a residential area in Tucson, Arizona. We identified the microbes present in the soil by sequencing a 16S rRNA gene marker and using a program called FAPROTAX. This program mapped the identified microbes to associated functions. I then conducted a literature review to link the identified microbes to functions they have been proven to perform. I focused on two functions involved in the breakdown of cell walls and exoskeletons, making them key for decomposition: chitinolysis and cellulolysis. I found that both functions have higher abundances in all GI systems compared to the control. This demonstrates that GI water harvesting treatments do impact soil microbial composition and function. This is important because it suggests that GI does alter the carbon cycle, which could have possible impacts on climate change, as carbon is a major greenhouse gas. In addition, GI systems may increase the availability of key nutrients by releasing locked compounds stored behind strong cell walls, exoskeletons, and cellulose. Increases in bioavailable compounds can lead to greater access by other organisms such as soil invertebrates and plants supporting growth and increased diversity.

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