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Lettice Hicks

Researcher | PhD

I am interested in understanding how soil biogeochemical cycles, regulated by the activities of soil microorganisms, will be influenced by global environmental change.

My PhD research (University of Edinburgh, UK) focused on how the direct effect of climatic warming, together with warming-related changes to plant productivity and species composition, will influence future carbon cycling in tropical soils. I used a large elevation gradient in natural forest and grassland, traversing 3400 m in elevation from the top of the Peruvian Andes to the Amazon lowlands, to investigate how temperature, soil nutrients, plant species composition and microbial community composition together affect rates of decomposition in tropical lowland and montane systems.

I will continue to investigate microbial responses to global change at the Rousk Laboratory, Lund University. My projects include both investigating how soil microbes respond to (i) altered moisture availability following periods of drought (together with PhD student Ainara Leizeaga) and (ii) a warmer Arctic with altered plant-inputs as a consequence of climatic warming.

Hydrological regimes will intensify due to climate change, resulting in an increase in the duration and intensity of drought and rainfall events. Rewetting of dry soil is known to stimulate dramatic carbon dioxide (CO2) releases from soils to the atmosphere. I will study the microbial responses underlying this pulse of CO2 release, using radioisotope tracer based methods to measure bacterial and fungal growth at high temporal resolution.

Climate change is also modifying the plant community, thus modifying the type of, quantity and chemistry of plant-derived carbon inputs to soil. I will investigate how warming-induced changes to plant inputs can influence carbon and nitrogen cycling through ‘priming effects’, and their microbial underpinnings. Stable isotopes will be used to identify sources of respired carbon (i.e. carbon derived from either the added substrate or from native soil organic matter), which will be linked to responses in the growth rate of microbial groups, and also traced into functionally active microorganisms (microbial PLFAs). I will also use the 15N pool-dilution method to determine nitrogen mineralisation following the addition of added substrates, to assess whether carbon and nitrogen mineralisation is coupled or decoupled during priming.

I will assess the microbial control of soil processes using a combination of lab-based experiments in parallel with assessments of soils from natural field-gradients and experiments. This will include using soils from natural precipitation gradients in Texas and Ethiopia, and rain-exclusion field experiments at several sites, as well as soils from the Swedish subarctic and tropical forests in Peru.

Publications

Retrieved from Lund University's publications database

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Publications

Retrieved from Lund University's publications database

Publications

Retrieved from Lund University's publications database

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