Modelling the role of mycorrhizal associations in soil carbon cycling: insights from global analyses of mycorrhizal vegetation

Abstract

This research aims to investigate how different types of mycorrhizal associations affect soil carbon cycling, explore the mechanisms underlying their impact on plant litter decomposition, and assess how these dynamics vary across different ecosystems and climatic conditions, thus enhancing our understanding of mycorrhizal ecology at a global scale. In this thesis, through the use of a modelling approach supplemented with lab experiments, to examine the role of mycorrhizae in the global carbon cycle, we seek to elucidate the complex interactions between mycorrhizal fungi, soil carbon, and environmental factors, ultimately providing insights into the implications of the current and future distributions of mycorrhizal associations for soil carbon storage in the face of global environmental change. I quantitatively explored the direct impact (fungal biomass as carbon input, Pathway Ⅱ, Figure 1.2-c) and mediation effect (through influences on litter decomposition, Pathway Ⅲ, Figure 1.2-d) of different types of mycorrhizal fungi on soil carbon, addressing the following research questions: (1) How do mycorrhizal effects on soil carbon cycling vary between different types of mycorrhizal associations? (Chapter 2 and Chapter 3) (2) How can we incorporate the mechanisms through which mycorrhizae impact plant litter decomposition in modelling? (Chapter 3) (3) How does the impact of mycorrhizal associations on soil carbon vary across different types of ecosystems in various climates? (Chapter 4) (4) How does global environmental change influence the distribution of mycorrhizae in the future and how could this influence the future soil carbon storage? (Chapter 5)