Project

How do different soil processes respond to changes in temperature?

Soil organic matter (SOM) stores large amounts of organic carbon. Under the influence of climate change, higher temperatures have the potential to stimulate SOM decomposition, accelerating the release of carbon dioxide into the atmosphere. If carbon loses are higher than photosynthetic inputs, increased SOM decomposition can positively reinforce the feedback to climate change.

Background

SOM decomposition rates are controlled by biotic (i.e., enzymatic depolymerisation) and abiotic (i.e., sorption-desorption, diffusion) processes that are significantly affected by temperature changes. Recent research suggest a distinctive pattern in the response of biotic processes, demonstrating a unimodal relationship with a clear temperature optimum. In contrast, abiotic processes tend to exhibit an exponential increase as temperatures rise. However, there is a need for a robust empirical experiments testing these hypothesis.

In this thesis, you will evaluate the temperature response of biotic and abiotic processes independently. You will incubate a range of samples with different soils, substrates, and microbial communities in a temperature gradient block and measure CO2 production. Additionally, you will conduct measurements on soil pH, DOC, mineralogy and microbial composition, and depending on your interest, possibly other techniques. You will learn to analyse complex datasets and use multiple statistical approaches.

Literature:

  • Conant, et al. Temperature and soil organic matter decomposition rates - synthesis of current knowledge and a way forward. Glob. Chang. Biol. 17, 3392–3404 (2011);
  • Robinson, et al. Rapid laboratory measurement of the temperature dependence of soil respiration and application to changes in three diverse soils through the year. Biogeochemistry 133, 101–112 (2017);
  • Schipper, et al., Shifts in temperature response of soil respiration between adjacent irrigated and non-irrigated grazed pastures. Agriculture, Ecosystems and Environment 285 (2019).

Used skills

  • Literature review;
  • Writing proposal and thesis;
  • Experimental design;
  • Laboratory skills;
  • Data analysis.

Requirements

  • Required courses for MSc thesis in Soil Biology OR Soil Chemistry and Chemical Soil Quality.