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Harvard Forest REU Symposium Abstract 2011

  • Title: Soil Respiration and Its Response to Manipulation Treatments
  • Author: LETICIA R DELGADO (Northern Arizona University)
  • Abstract:

    Forest ecosystems contain more than two-thirds of their carbon in the soil. Soil respiration is the release of carbon from belowground (roots and microbes) into the atmosphere. Respiration rates are affected by various environmental and anthropogenic factors including: temperature, moisture, nitrogen addition, root removal and increased litter levels. This project explores the CO2 flux at five different manipulated treatment sites located in the Prospect Hill and Tom Swamp tract in Harvard Forest. Throughout the summer, five cycles of CO2 flux, temperature and moisture measurements were collected at each of the following manipulation sites: Warming, Trenching, Nitrogen Amendment, Detritus Input and Removal Treatments (DIRT), and Ants. Soil flux measurements were taken using the LICOR-6400 infrared gas analyzer. The warming site is a model of how future global warming will influence soil respiration rates. Results from this site can also be used to predict how the carbon flux will change in the natural gradient sites. At the trenching site, roots have been isolated to allow only for microbial respiration; flux rates for the trenched plots were on average 3.231383 µMol*m-2s-1 lower than the control plots. Data collected at the nitrogen addition site showed lower flux values as nitrogen levels increased in the hardwood stand but was inconsistent in the pine stand. Litter manipulation, DIRT, showed the highest flux values in plots with double litter and the lowest flux values in plots with no above or below ground inputs. The ant site consists of buckets containing three different soil types and ants placed under three different temperature treatments. CO2 flux at the ant site was higher in the heated plots containing ants than the controls. Understanding data from a manipulated site allows us to make predictions on the response of CO2 flux to that variable across a gradient.

  • Research Category: Soil Carbon and Nitrogen Dynamics