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Pellegrini Group: Ecosystem and biogeochemical reassembly after fire on peatlands

NERC / UF / OTHER

Supervisor: Adam Pellegrini (Plant Sciences)
Co-supervisor: Prof David Coomes

Importance of work

Climate change is increasing the frequency and intensity of fires in many ecosystems across the globe. Peatlands are experiencing some of the largest changes in fire, which is problematic because they store and sequester large amounts of carbon and are globally distributed. Although the immediate effect of fire via the combustion of peat is well understood, the long-term implications for changing soil biogeochemistry is unclear. One hypothesis is that following fire, decomposition of soil carbon accelerates, causing large sustained long-term losses of carbon from the ecosystem. The alternative hypothesis is that fire reduces decomposition by increasing the recalcitrance of organic matter, and the colonization and growth of plants results in the rapid re-sequestration of the carbon lost in the fire. This project will involve research across peatlands in the Flow Country (northern Scotland) where a series of field sampling campaigns will be combined with lab measurements to evaluate the long-term implications of fire for peatland carbon storage and test the alternative hypotheses.

Project summary

The project will take place in northern Scotland where wildfires have burned areas spanning a variety of ecological contexts and the plots differ in their fire history. Sampling of plant biomass and soil organic matter will be used to quantify the total stocks of carbon in the ecosystem. Changes in carbon cycling will be evaluated by monitoring plant growth combined with analyses of soil carbon cycling using in situ measures of microbial activity and laboratory measurements of specific microbial enzymes. Measurements of organic matter chemistry, charcoal content, and microbial communities 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 5-10 different field sites dispersed throughout the Flow Country that vary in their time since last fire. Time will be spent conducting vegetation measurements and monitoring soil CO2 production 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 collaborative work with researchers in Scotland will give them exposure to working in collaborations and allow them to create a strong research network. Moreover, the student will be involved with a collaboration with the Royal Society for the Protection of Birds (who manage reserves in the Flow Country), providing exposure to non-academic organizations.

References

  • A. F. A. Pellegrini, 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.

  • A. F. A Pellegrini, S. E. Hobbie, P. B. Reich, A. Jumpponen, E. N. J. Brookshire, A. C. Caprio, C. Coetsee, and R. B. Jackson. 2020. Repeated fire shifts carbon and nitrogen cycling by changing plant inputs and soil decomposition across ecosystems. Ecological Monographs: e01409.

For details on how to apply to the Cambridge NERC Doctoral Training Partnerships see https://nercdtp.esc.cam.ac.uk/  

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