Wednesday, August 8, 2007PS 41-26: Microbial community structure and nutrient cycling dynamics in soils exposed to chronic warming and nitrogen additions: Preliminary results
Alexandra R. Contosta and Serita D. Frey. University of New Hampshire
A new study at the Harvard Forest Long Term Ecological Research site examines how warming and nitrogen additions act alone and together to impact soil C and N cycling, microbial community structure, and microbial community function. During the fall of 2005, we installed twenty-four 3x3m plots and assigned them one of four treatments: control, N addition, warming, and warming plus N. In early August 2006, we initiated the heating and the fertilization treatments. Since then, we have heated the plots to 5°C above ambient soil temperature using buried heating cables. We also have applied N as an aqueous solution of NH4NO3 in doses equivalent to an N deposition rate of 5 g N m-2 y-1. In June 2006, we started taking monthly soil samples and soil water samples, and bi-monthly soil respiration measurements. Soil samples are used to quantify: soil moisture, nitrogen mineralization rates, labile carbon pools, and soil enzyme activity. Our pre-treatment data indicates no differences among plots in microbial enzyme activity, labile carbon availability, soil moisture, soil respiration and DIN concentrations in soil water. After initiating the experimental treatments, labile C availability, enzyme activity, and DIN did not respond to warming and fertilization. Soil respiration showed an immediate response to heating and nitrogen additions, such that CO2 flux rates in the heated and the heated plus nitrogen plots have increased about 40% relative to the controls.
See more of PS 41 - Cycling - nitrogen
See more of Contributed Oral and Poster Abstracts
See more of The ESA/SER Joint Meeting (August 5 -- August 10, 2007)
See more of Contributed Oral and Poster Abstracts
See more of The ESA/SER Joint Meeting (August 5 -- August 10, 2007)