Dr. Josh Hashemi

Biography

Josh Hashemi studied Biology with a focus in plant ecophysiology and restoration ecology at Kennesaw State University (B.Sc.). He attended the University of California in Davis for his PhD in Ecology from 2017-2022 studying greenhouse gas (CO₂, CH₄, and N₂O) exchange dynamics in pristine Arctic tundra. He completed his dissertation, entitled “Variability in Greenhouse Gas Dynamics due to Spatial Heterogeneity and Seasonality in Alaskan Arctic Coastal Wetlands” in 2022. He began research as a post-doc at the Chair of Environmental Meteorology, University of Freiburg in May, 2022.

Research

Currently, his research examines greenhouse gas exchange as part of the Pilot Applications in Urban Landscapes (PAUL) project. Specifically, his focus involves using eddy covariance towers to take measurements of ratios of CO₂ fluxes to fluxes of co-emitted species (e.g. NO_x, CO, COS) to examine the relative contribution of different sectors (traffic, residential, biogenic etc.) in urban landscapes. Additionally, his research involves partitioning CO₂ emissions into fossil fuel CO₂ (ffCO₂) and biogenic CO₂ using a combination of eddy covariance data and measurements of radiocarbon (¹⁴C).

Current Research Projects

•  ICOS Cities – Pilot Applications in Urban Landscapes (H2020)

Publications

Articles in peer-reviewed journals

• Zona, D., Lafleur, P.M., Hufkens, K. et al. (2022). Earlier snowmelt may lead to late season declines in plant productivity and carbon sequestration in Arctic tundra ecosystems. Scientific Reports, 12, 3986. 

• Hashemi, J., Zona, D., Arndt, K. A., Kalhori, A., Oechel, W. (2021). Seasonality buffers carbon budget variability across heterogeneous landscapes in Alaskan Arctic tundra. Environmental Research Letters, 16, 035008.

• Arndt, K. A., Lipson, D. A., Hashemi, J., Oechel, W. C., Zona, D. (2020). Snow melt stimulates ecosystem respiration in Arctic ecosystems. Global Change Biology, 26: 5042– 5051 

• Arndt, K. A., Oechel, W. C., Goodrich, J. P., Bailey, B. A., Kalhori, A., Hashemi, J., Sweeney, C., Zona, D. (2019). Sensitivity of Methane Emissions to Later Soil Freezing in Arctic Tundra Ecosystems. Journal of Geophysical Research: Biogeosciences, 124, 2595– 2609.