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Pellegrini Group: The effect of fire on coniferous forests in the western United States


Supervisor: Adam Pellegrini (Plant Sciences)

Importance of work

Climate change is causing fires to become more frequent and intense in many ecosystems across the globe, generating 'novel' fire regimes that stress an ecosystem. These rapid changes are concentrated in particular ecosystems such as high-alpine and latitude coniferous forest ecosystems, which coincidentally also are critical reservoirs for carbon. One hypothesis is that intensifying fire regimes in these ecosystems will produce large losses of carbon and biodiversity, but that losses will be greatest in drier ecosystems with a lower capacity to recover; an alternative hypothesis is that losses will be greatest in wet ecosystems because of the lack of adaptative traits that plants could use to tolerate fire. Furthermore, the resilience of soil carbon cycling to fire is expected to be coupled with the resilience of plants. This project will involve research across several ecosystems located across the western United States (California and Arizona). A series of field measurements and laboratory analyses will characterize key plant traits, carbon stocks and fluxes from soils and vegetation to test alternative hypotheses about the mechanisms structure ecosystem resilience.

Project summary

The project will take place in three main sites with fire manipulation experiments (Sequoia and Kings Canyon National Parks both located in California, USA, and experimental forests in Flagstaff, Arizona, USA). Sampling of plant growth and carbon storage in a gradient of plots exposed to different burning frequencies will be used to quantify the regrowth and resilience of vegetation to fire. Analyses of soil carbon cycling using in situ measures of microbial activity and laboratory measurements of specific microbial enzymes, and δ14C will be used to quantify carbon turnover, while measurements of microbial community composition, organic matter chemistry, and charcoal content will be used to determine the mechanisms controlling the carbon turnover.

What the student will do

The project will combine both field and lab work.

  1. Fieldwork: Fieldwork will be carried out in 10 different field sites dispersed throughout  Sequoia and Kings Canyon National Parks (California, USA), and experimental forests around Flagstaff (Arizona, USA). Time will be spent conducting vegetation measurements during the growing seasons in the field and collecting soil samples for future analyses in the lab.
  2. Labwork: Analyses of several plant physiological traits as well as biogeochemical variables in the soils (e.g., the amount and form of carbon and nutrients) will be carried out in the lab.

Training to be provided

The student will be trained in field survey and sampling techniques, biogeochemistry (carbon and nutrient measurements in soils, organic matter chemistry, and mineral-carbon interactions), and microbiology (microbial biomass, respiration assays, extracellular enzyme assays). Moreover, the broad geographical scope will give them exposure to working in international collaborations and allow them to create a strong research network.


  • Pellegrini, A.F.A.A.F.A., W.R.L.W.R.L. Anderegg, C.E.T.E.T. Paine, W.A.W.A. Hoffmann, T. Kartzinel, S.S. Rabin, D. Sheil, A.C.A.C. Franco, and S.W.S.W. Pacala. 2017. Convergence of bark investment according to fire and climate structures ecosystem vulnerability to future change. Ecology Letters 20:307–316.
  • Pellegrini, A.F.A., A. Ahlström, S.E. Hobbie, P.B. Reich, L.P. Nieradzik, A.C. Staver, B.C. Scharenbroch, A. Jumpponen, W.R.L. Anderegg, J.T. Randerson, and R.B. Jackson. 2018. Fire frequency drives decadal changes in soil carbon and nitrogen and ecosystem productivity. Nature 553:194–198.

Applying: To the Cambridge NERC C-CLEAR DTP programme:


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