Broadly, my research focuses on understanding drivers of soil carbon cycling and stabilization across ecosystems.
Some of my active fields of research include:
Global Change, Management and Topography Effects on Soil Carbon Dynamic and Sequestration
For my research, I use a series of analytical approaches, including total soil organic carbon and nitrogen analysis, Soil organic carbon density fractionation, isolation of water extractable carbon, ultraviolet absorbance, infrared spectroscopy, and radioisotope tracing (137Cs, 14C) in combination with terrain analysis to investigate the quality and distribution of soil organic carbon.
Soil carbon dynamic and sequestration
The role of soils in the global carbon cycle is of the upmost importance. Soil systems have the potential to offset large amounts of carbon and, currently, soils store over three times the amount of carbon contained in the atmosphere. However, questions remain on how soils from different ecosystems, latitudes, and management will respond to a changing climate. Accurate and reliable predictions of future terrestrial carbon sinks rely on our understanding of soil organic carbon decomposition responses to warming. While kinetic theories predict a strong response to an increase in temperature and greater temperature sensitivity for the fraction of soil organic carbon considered “recalcitrant,” enzyme activity may be dependent on substrate availability.To address the uncertainty of whether substrate supply affects soil organic carbon decomposition more than temperature, I developed an incubation study that led to the publication below:
Fissore, C., Giardina, C.P., Kolka, R.K. 2013. Reduced substrate supply limits the temperature response of soil organic carbon decomposition. Soil Biology and Biochemistry 67: 306–311
Our study suggests that, among temperate forest soils, substrate supply limits microbial activity and therefore soil organic carbon decomposition. Nevertheless, our findings support the view that, in many regions, warming may lead to more soil organic carbon being decomposed. If, as predicted, warming will largely affect carbon-rich soils (such as organic soils) located at northern latitudes, then increased decomposition of the most labile fraction of soil carbon will likely exacerbate global warming.
I am particularly interested in better understanding the role of clay minerals on wood decomposition. To address the existing knowledge gap, I developed a long-term, highly controlled mesocosm study that investigated wood decomposition in relation to two clay types (kaolinite and montmorillonite), three clay amounts (8%, 16%, 24%), three incubation temperatures (10°C, 20°C, 30°C), and three placements with respect to soil (in the mineral soil, on the soil surface, on top of the litter layer). Findings from this incubation study have been published in the journal Ecosphere.
Soil organic carbon stabilization is also a function of topography. Erosion and deposition processes can largely affect soil organic carbon stabilization through processes of renewal and burial, among others. Topographic features, such as slope and curvature, control rates of soil translocation and, consequently, can affect quantity and quality of soil organic carbon along a hillslope system. Erosion can expose more fresh mineral surfaces, which can incorporate fresh and more labile carbon that will become part of the ‘new’ topsoil. Conversely, depositional processes may lead to long-term soil organic carbon stabilization through burial at depositional sites. My work so far has produced the following publication:
Fissore, C., Dalzell, B. J., Berhe, A.A., Voegtle, M.*, Evans, M.*, Wu, A. 2016. Influence of topography on SOC dynamic in a Southern California grassland. Catena 149: 140-149 DOI: 10.1016/j.catena.2016.09.016
Soil health in sustainable agriculture production in California
Coffee is a new crop for Southern California and there is lack of knowledge concerning the potential role of growing organic coffee-avocado intercropping in sustainable agriculture. Therefore, it is my goal to investigate and compare soil quality and water use efficiency of intercropping systems, and specifically, in more traditional avocado orchards in the area.
Urban ecosystems, being characterized by high population density and large input and output fluxes of elements and material, are considered biogeochemical hotspots. There is growing interest in the role of urban ecosystems in the global cycling of elements, especially in consideration of the role played by human decisions and behavioral factors on such cycles. With my work, in collaboration with the Twin Cities Household Ecosystem Project (TCHEP) team at the University of Minnesota (https://www.tchep.umn.edu), I investigated biophysical drivers of carbon, nitrogen, and phosphorus cycles in an urban-to-suburban gradient in Saint Paul, MN. One aspect of the research focuses on biogeochemical fluxes within the residential landscape. Based on the extensive survey and field-derived dataset obtained by our team, I analyzed fluxes of carbon, nitrogen, and phosphorus through the residential landscape.Our work highlighted the important role played by individuals’ decisions and behaviors in affecting residential fluxes through the landscape. Additionally, the study informed on potential sources of urban pollution from the residential landscape.