Researching How Forest Type, Disturbance, and Management Influences the Storage and Cycling of Key Elements in Soils and Vegetation
About My Research
My research has primarily focused on carbon, water and nutrient cycling in forested ecosystems, ranging from northern hardwood forests to intensively managed southern pine forests to coastal forested wetlands. My research has specifically addressed knowledge gaps related to how forest type, disturbance, and management influences the storage and cycling of key elements in soils in vegetation. Research I conducted for my dissertation work directly addressed the role of forest soil carbon and multi-use bioenergy production systems in mitigating climate change and helped inform management decisions related to carbon sequestration and greenhouse gas emissions reduction and in sustainable forest practices. For my post-doctoral research, I focused on above- and below-ground cycling of carbon soil microbial processes that determine CO2
and CH4 release from peat soils of coastal freshwater forested wetlands. Recently, my research has also expanded to using deuterium tracing methods in mature trees in order to refine our understanding of how trees store and transport water and how tree water cycling is influenced by environmental stressors such as drought.
My research has helped advance theoretical frameworks for understanding the role soil microbial processes in relation to soil carbon and nutrient transformations, through the combination of novel field and laboratory experimentation. For example, studies I have conducted (using eddy flux techniques, Picarro-assisted CH4 isotopic natural abundance, and laboratory incubations) on the role of methanogenic soil microbial functioning in freshwater wetland ecosystems of coastal North Carolina helped elucidate biotic drivers of wetland CH4 production, the CH4 production pathways, and the environmental factors that influence CH4 production.
Thus, the knowledge gained from this research has had important implications for policy, theory, and practice, particularly in the area of sustainable forest management and climate change impacts on forest health and productivity. By providing insights into the complex interactions between the plant-soil-atmosphere continuum this research has helped to inform decision-making and promote sustainable management practices.
How Picarro Analyzers Helped
Ecological research often involves the study of complex environmental systems, and isotopic analysis can provide valuable information on the movement and cycling of elements and compounds within those systems with high precision and accuracy. I have used Picarro isotope analyzers in a range of different studies, such as: 1) tracing of 99.9% APE deuterated water within trees;2) measurements of 13C natural abundance of CO2 and CH4 arising from wetland soils to determine their sources and sink and the microbial processes responsible for generating these greenhouse gases;and 3) tracing breakdown of 13C-labelled C into various soil organic matter pools. Overall, Picarro analyzers are powerful tools for a diversity of ecological research, providing researchers with the ability to make precise measurements (in the field and laboratory) of isotopic ratios on a wide range of environmental samples and is an essential tool in answering specific ecological research questions and test hypotheses.
One of the more unique challenges I encountered was with the G2201-i Isotopic CO2/CH4 analyzer during a laboratory incubation. I collected peat samples from a freshwater wetland in coastal North Carolina and incubated them in the laboratory with either freshwater or salt water to mimic effects of sea level rise on freshwater wetland salinization, which is occurring at an alarming and globally significant rate in coastal areas of North Carolina. As the incubation got underway, I quickly ran into issues involving the interference of H2S in gas samples generated from soils incubated with salt water (arising from sulfate-reducing microorganisms). This caused major issues in the analytical capabilities of the Picarro isotopic measurements. Over the next week, I researched remedies which led to my assembling of a H2S oxidizing trap (using Cu oxide shavings) which was subsequently installed into the gas line running into the Picarro. This had a positive and immediate effect on the isotopic values and allowed me to continue my incubation experiment with only a small data gap. This story, to me, exemplifies the utility and flexibility of the Picarro isotopic analyzers. They allow the user flexibility for gas sample analysis and backend adjustments of sample type, sample delivery, etc. which is exceptionally useful to tailor the Picarro to your specific experimental needs.
Finally, my research with collaborators from Duke University, UGA, and Idaho State University, utilized a unique and unprecedented field set up for the in situ tracing of labelled water radially and axially in mature trees using a new borehole method. A vehicle was rented for the extended field season in order to carry out this work, and was equipped with two Picarro water isotope analyzers which were powered by a generator. I measured the 2H isotopic signature of water vapor arising within the boreholes and developed 2H breakthrough curves for assessment of how trees store and move water with a spatially and temporally robust measurement regime. None, of this exciting work could have been accomplished without the use of these critical instruments developed by Picarro.