Plants have been central to life on land for over 400 million years, during which time environmental conditions have changed dramatically.
Plants’ responses to changing environmental conditions can include changes in leaf chemistry, which encompasses: i) lignin, cellulose and other cell wall components, the most abundant organic polymers on the planet and a significant sink for photosynthetically fixed carbon. ii) proteins, peptides and amino acids, an important aspect of nutritional value for herbivores. iii) lipids, such as leaf wax n-alkyl compounds and triterpenoids, which provide physical and chemical protection for the plant and are widely used in palaeoclimate and palaeoenvironmental reconstructions.
Together, these chemical components determine the quality and reactivity of leaf organic matter, ultimately influencing terrestrial carbon sequestration, which can feed back to influence atmospheric composition. Changes in leaf chemistry driven by temperature, precipitation or other environmental variables have received limited attention, especially in temperate climates. Additionally, the utility of leaf chemistry to investigate plant response to environmental change in the Quaternary has not been fully investigated.
The aim of this project is to determine baseline leaf chemistry for a range of living fossil and native UK species and investigate how these species respond to changing environmental conditions along natural climate gradients. Leaf chemistry will be compared to other leaf traits (e.g. leaf mass per area, leaf shape) to determine if variations in leaf chemistry co-vary with other traits known to respond to environmental pressures. The project will also investigate leaf chemistry preservation in a range of Holocene sediment cores from arctic, temperate and tropical sites to determine if and how leaf chemistry tracks environmental change in these different locations over long timescales. This will allow us to investigate responses at specific locations, but also determine whether the relationships can be scaled up to global scale fluxes over long timescales.
You will work with scientists at the University of Leeds, National University of Ireland, Galway, and botanic gardens around the UK to quantify leaf chemistry changes over temperature/precipitation gradients and to understand how these signals can be used to interpret palaeoecology. In particular, according to your particular research interests, the studentship could involve:
1. Characterising leaf chemistry for “living fossil” taxa that have previously not been fully investigated. 2. Evaluating the changes in leaf chemistry of selected taxa along climate gradients. 3. Comparing leaf chemistry to other leaf traits associated with plant responses to environmental change. 4. Investigating the leaf chemistry signal and its utility as a palaeoecological tool in a range of Holocene sediment and peat cores from arctic, temperate and tropical biomes. 5. Investigate the implications of changes in leaf chemistry on the environment and carbon cycling under Holocene and future climate change, utilizing climate model simulations incorporating a dynamic vegetation model.
The project will directly investigate the potential links between leaf chemistry and environmental change. The wider question that this project will contribute to is “How do changes in leaf organic matter (OM) quality associated with environmental changes affect the fate of that OM in the global carbon cycle?”. This has implications for understanding how terrestrial ecosystems have responded to past environmental change and how they may respond in the near and medium term future (Figure 1), making the research timely and likely to produce several outputs, including 3–4 publications, at least one of which we anticipate being suitable for submission to a high-impact journal.