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Harvard Forest REU Symposium Abstract 2012

  • Title: Soil Microbial Enzyme Potentials in Response to Forest soil Warming
  • Author: Lauren Alteio (SUNY College of Environmental Science and Forestry)
  • Abstract:

    Global climate change is impacting the function and health of our forest ecosystems. Soil plots at Prospect Hill have been heated five degrees Celsius above ambient temperature for twenty-one years to mimic the effects that rising global temperatures may have on northeastern hardwood forests. Over the past 21 years, the difference in the amount of CO2 respired from heated and control plots has changed: initially, the amount was greater in the heated plots than in the control. Between years ten and fifteen of the study, there was a negligible difference in CO2 respired, but this difference is now increasing again. Our hypothesis states that this change is due to microbial community shifts, allowing soil microbes to produce enzymes to break down alternative carbon sources. This summer, I explored the possible reasons for this increase in CO2 respired by examining microbial enzyme potential through enzyme assays. This methodology allows us to view potential microbial activity and metabolic mechanisms in the lab, and apply the findings to in situ activity. I expected the level of hydrolytic activity of β-1,4-Glucosidase, β-D-1,4-Cellobiosidase, and β-N-Acetylglucosaminidase to be greater in the control plots where simpler, labile compounds are more readily available. I also projected that the activity of the oxidative enzymes, Phenol Oxidase and Phenol Peroxidase, would be greater in the heated plots where labile compounds have largely been depleted and more recalcitrant compounds remain. I conducted three rounds of enzyme assays using organic horizon soil from the heated and disturbance control plots at Prospect Hill. I plated the twelve soil slurry samples, and read the fluorescence and absorbance using a microplate reader. I found that there was a significant difference in enzyme activities between months, but not between heated and disturbance control treatments. For some enzyme activity potentials, I found the percent soil moisture affected enzyme activity.

  • Research Category: Forest-Atmosphere Exchange; Large Experiments and Permanent Plot Studies; Soil Carbon and Nitrogen Dynamics