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Harvard Forest REU Symposium Abstract 2011

  • Title: Acidiobacteria and Proteobacteria Found to Dominate Harvard Forest Soil Samples
  • Author: Kelden M Pehr (MIT (Massachusetts Institute of Technology))
  • Abstract:

    Despite the preeminent importance of the carbon cycle, much remains unclear on the influence of particular feedback systems upon the changing cycle. One such feedback, the fluctuation of carbon stored in the soil, may be caused by the alteration of microbial communities in response to warmer climates. Past studies have shown that soil carbon respiration increases for a short period of time in warmer plots before leveling off and then increasing again. One theory suggests that microbial communities quickly use up the available labile soil organic carbon pool, and must then shift toward optimizing the use of other available carbon sources. To test this, we will be looking at microbial community diversity and function in warming and control plots at Harvard Forest. We will evaluate microbial community composition and function by analyzing soil samples collected at four time points from warming and control plots at Barre Woods, in Harvard Forest, to determine the response of microbial communities to a warming soil ecosystem. To date we have collected two points and are waiting to sequence them. As a parallel study, we analyzed unpublished metagenomic sequence data of 60 soil samples from Prospect Hill in Harvard Forest, generously made available by Bill Landesman. Using a pipeline of python scripts, collectively known as QIIME (Quantitative Insights Into Microbial Ecology), we looked at microbial taxonomy along with diversity among and between the collected soil samples. Our analysis revealed the dominant phyla present in the soil samples to be (in decreasing order) Acidobacteria, Proteobacteria, Actinobacteria, Verrumicrobia, Bacteroidetes, and Planctomycetes, all common soil phyla. The representative phyla in each sample were relatively consistent, although slight correlations were found with regards to soil pH and tree species near at the site of individual samples. This study provides the first insights into the bacteria that are present in Harvard Forest soils. This analysis will provide a foundation for the interpretation of our Barre Woods study.

  • Research Category: Physiological Ecology, Population Dynamics, and Species Interactions