CARI D. FICKEN
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    • Effects of human land use on boreal wetlands
    • From plants to ecosystems: Scaling the impacts of disturbance
    • Drought sensitivity of soil biota
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Plant-mediated responses of ecosystem functions to fire and nitrogen fertilization in longleaf pine forests

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My PhD research examined how the impacts of disturbances on ecological process are mediated by plants.

​Working mostly in longleaf pine forests, I found that soil inorganic nitrogen increases for a short period of time after a fire. This pulse occurs, in part, because plants reduce their nitrogen capture after they burn. However, these plants are well-adapted to the low intensity fires that occur every few years in longleaf pine forests, and they begin to resprout only a few days after a fire. Does this nitrogen pulse contribute to plant resprouting success? In a series of greenhouse and mesocosm experiments, I found that co-dominant species differed in their nitrogen capture and this ability was positively associated with resource acquisitive functional traits. However, differences in resource capture did not translate to a competitive advantage because biomass regrowth was negatively associated with similar resource acquisitive functional traits. Thus, the effect of fire on plant competition was mediated by a physiological tradeoff between fast resource capture, and fast biomass regrowth.
 
In a follow up field study, I found that fires influence understory productivity through their long-term legacy impacts on plant regrowth strategies. Individuals exposed to frequent historical fires resprout quickly in the short-term to a subsequent disturbance. Over a full growing season, however, these individuals have lower performance than individuals exposed to infrequent disturbances. These results indicate that the historical disturbance regime is a stronger driver of plant productivity and competitive ability than short-term changes to resource availability after disturbance.


Ficken, CD and JP Wright. 2018. Nitrogen uptake and biomass resprouting show contrasting relationships with resource acquisitive and conservative plant traits. Journal of Vegetation Science. doi: 10.1111/jvs.12705. 

Ficken, CD and JP Wright. 2017. Effects of fire frequency on litter decomposition as mediated by changes to litter chemistry and soil environmental conditions. PLoS ONE. doi: 10.1371/journal.pone.0186292.

Ficken, CD 
and JP Wright. 2017. Contributions of microbial activity and ash deposition to post-fire nitrogen availability in a pine savanna. Biogeosciences. doi:10.5194/bg-2016-303.

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  • Home
    • About the lab
    • Contact
  • Research
    • Effects of human land use on boreal wetlands
    • From plants to ecosystems: Scaling the impacts of disturbance
    • Drought sensitivity of soil biota
    • Older projects
  • CV
  • Publications