Carbon and Nutrient Cycling in Forests

We are working to resolve the effects of geology, disturbance and climate variability on forest soil C and nutrient dynamics in Appalachian forests.

Carbon cycling in the Critical Zone

 The flux of CO2 from soils to the atmosphere is one of the largest components of the global C cycle.  In forests, this flux varies tremendously in space and time.  Discovering the source of this variation is important for scaling up plot-level soil respiration measurements and refining regional and global carbon models.  At the Susquehanna-Shale Hills Critical Zone Observatory we are monitoring soil CO2 concentrations and fluxes on concave and planar slopes along transects from the ridge top to the toe slope. Simultaneously, we monitor soil temperature, water, oxygen, and nitrous oxide.  These data will increase our understanding of how soil development and soil moisture variability control the accumulation of CO2 in soil pore spaces and the flux of CO2 from soils to the atmosphere.

The response of harvested forests to climate change

A field-based climate change simulation experiment was maintained from 2008 to 2011 in Penn State's Stone Valley Forest to identify the responses of soils and tree species to predicted increases in temperature and precipitation.  Research plots were heated by ~2 degrees C with suspended infrared lamps and irrigated with +20% of the average long-term precipitation in a forested area that was harvested prior to the experiment.  In the plots we monitored: tree seedling growth, phenology, and ecophysiology; early successional community composition and phenology; and soil temperature, moisture, nutrient fluxes, nutrient pools, and soil biotic community responses.  See publications by graduate students Marshall McDaniel, Rebekah Wagner, and Christie Rollinson.