Research

Our research program strives to increase our understanding of the processes of carbon (C) and nitrogen (N) cycling in terrestrial ecosystems, and how human-induced disturbance influences these processes. The perturbation of these cycles has enormous consequences to humans.

Changes in the C cycle, particularly those that release C to the atmosphere, will contribute to rising levels of carbon dioxide in the atmosphere and rates of climatic change. Nitrogen deposition may enhance forest growth rates, but excess N can lead to reduced soil and water quality and increased emissions of greenhouse gases such as N2O.

The key research questions are -

  1. How do forest management practices and other disturbances particularly non-stand-replacing events, alter rates of C exchange with the atmosphere?
  2. How does conversion of former agricultural land to forest influence soil C storage?
  3. What is the fate of different forms of N added to forest ecosystems, and how does this exogenous N influence rates of C exchange between the forest and the atmosphere?

Dr. Scott is also interested in the impact of invasive plant species on plant/soil interactions, and the impact of historical land-use patterns on contemporary C and N cycling processes. His research approach includes field studies, development and testing of process-based terrestrial C and N cycling models, and the use of remote sensing and GIS to extrapolate research results in space and time. When possible, I try to use my research results to help address key environmental policy issues.

Soybean Nitrogen Dioxide Project

Legume plants have the unique feature of both fixing N2 and producing H2 gas (as a byproduct of the nitrogenase reaction) in root nodules. The H2 diffused to soil surrounding the nodules can stimulate the population of some soil microbes which could stimulate plant growth (Plant Growth Promoting Rhizobacteria), building soil carbon pools, and increasing N2O (a potent greenhouse gas) emissions.

Over the past 3 years, our research has shown that long term (weeks) exposure of soil to elevated concentrations of H2 (similar to that experienced by soils adjacent to legume nodules) in the laboratory, results in a major increase in the emission of N2O. In collaboration with scientists at the Agriculture and Agri-Food Canada, Eastern Cereal & Oilseed Research Center, Ottawa, we established field trials of soybeans (Glycine max cv. Bravor) on soil that had not seen legumes for at least 20 years. We measured soil atmosphere N2O concentrations in the field, and soil N2O emissions in the laboratory using soils collected from soybean field over the last two years. Soil adjacent to nodules had significantly higher rates of N2O emission than soil near roots lacking nodules, giving evidence of enhanced N2O emissions related to the legume symbiosis.

Further work will explore soil properties and the mechanism leading to enhanced N2O production associated with H2 uptake in soil. Field trials are underway to quantify the growth promotion effects in plant biomass and yield of barley, corn and wheat crops.

Current Funded Projects

(section currently being updated)