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Sam Flake

Graduate Student | Department of Plant Biology | NC State University

2019-20 Global Change Fellow

Where are they now?

Sam is now a postdoctoral research scholar in the Department of Forestry and Environmental Resources at North Carolina State University.

Statement of purpose:

I study the processes that limit tree growth and forest development trees near the edges of their physical tolerances. It is at these places that large effects of global change processes are likely to be most readily seen, where only a small change is needed to push a system past a tipping point. While I’ve worked with a variety of ecosystems and taxa, what has unified my research is a focus on disturbances, environmental gradients, and how they affect one another. While my research is primarily of a basic nature, seeking to understand how disturbances and vegetation affect one another, my goal is to conduct basic research that is clearly relevant to the management and conservation of rare ecosystems and useful for forecasting the effects of altered disturbance regimes.

Description of research:

My current work focuses on the dynamics of savannas (grassy ecosystems with partial tree cover) and forests (with a closed tree canopy), especially how those dynamics interact with fire, whether wild or prescribed. In the absence of disturbance such as fire, savannas may be displaced by forest, with devastating effects on the diversity of specialized savanna species. In other places, forests are at risk of transformation to non-forested systems like savanna or chapparal. Predicting where and when these transitions will occur is complicated because of feedbacks between forest cover and disturbance processes. For example, as forest cover increases, fuels on the ground are often reduced, preventing the low-intensity fires that keep the understory open and allow savanna species to survive. Because of these feedbacks, the details of how forests develop are important – especially because many of the drivers of disturbance and forest growth are sensitive to global change processes, like land use change or temperature increases.

Among the questions I am exploring are: How do the attributes of different species contribute to rates of forest development? How are the interactions between dominant species, such as longleaf pine and turkey oak, changing? How susceptible are different species to fire? What are the impacts of fire regimes on plant communities? I am addressing these questions using several approaches: tracking the changes in savanna and forest composition over time and in response to prescribed fire; measuring “functional traits,” or aspects of plant morphology of physiology that influence their ecology; and developing a simulation modeling framework to explore how different global change processes might change where forests are found in the future. My research is aligned with DOI Priorities 1 and 2, in particular Utilize science to identify best practices to manage land and water resources and adapt to changes in the environment and Refocus timber programs to embrace the entire ‘healthy forests’ lifecycle.

Contact Information:



  • Flake, S. W., Abreu, R. C. R., Durigan, G., & Hoffmann, W. A. (2021). Savannas are not old fields: Functional trajectories of forest expansion in a fire‐suppressed Brazilian savanna are driven by habitat generalists. Functional Ecology.
  • Flake, S. W., Honda, E. A., Pilon, N. A. L., Hoffmann, W. A., & Durigan, G. (2021). Not all trees can make a forest: Tree species composition and competition control forest encroachment in a tropical savanna. Journal of Ecology, n/a(n/a).
  • Flake, S. W., & Weisberg, P. J. (2021). Drought alters the understory of pinyon-juniper woodlands indirectly through tree dieback. Rangeland Ecology & Management, 76, 118–128.