The functioning of arbuscular mycorrhizal fungal networks in response to grassland management

Abstract

This comprehensive thesis focused on the roles of arbuscular mycorrhizal (AM) fungi within grassland ecosystems, emphasizing their contribution to plant performance across varying management practices and the complexities of plant-soil feedback (PSF) processes. I explored the impact of intensive and extensive grassland management on hyphae production and the development of common mycorrhizal networks (CMNs) and their influence on seedling growth, focusing on the differential responsiveness of subordinate and dominant plant species. Moreover, I provided insight into how CMNs can be managed effectively to maximize the functions and outputs from managed systems. Additionally, I investigated how microorganisms associated with plant monocultures and mixtures affect PSF under both intensive and extensive grassland management. Furthermore, the thesis examined how grassland management regimes, influenced by soil treatment (autoclaved vs. non-autoclaved), interact with plant species richness and identity to affect community biomass, soil properties, and plant responsiveness. First, I provided a review of the current AM fungi research before discussing the role of AM fungi in structuring the hyphal production, CMNs, as well as determining PSFs and responsiveness with different grassland management. In chapter 2, I found that extraradical mycelium and the formation of CMNs are sensitive to grassland management practices, with intensively managed grasslands supporting less mycelium and providing fewer opportunities for the growth and development of CMNs, which neither significantly enhanced seedling growth nor provided as much benefit to subordinate species as to dominant species. In chapter 3, the review highlighted the CMNs’ potential to enhance ecosystems functions and outputs when effectively managed, while also cautioning against overestimating their benefits and noting their possible negative impact on plant performance. In chapter 4, I also reported that plant species richness and specific management practices were found to significantly enhance plant growth and modify soil properties through positive PSF effects, although the outcomes from plant mixtures present complexities that cannot be straightforwardly predicted from single-species responses. In Chapter 5, I discovered that plant responsiveness is influenced by a complex interaction of factors, including plant species, grassland management practices, and autoclaving treatment. This highlights the critical role these factors play in shaping plant growth and nutrient dynamics, demonstrating their importance for developing effective strategies in sustainable grassland management and conservation, and ensuring that management practices to support both plant diversity and soil fertility. This research demonstrated the critical need to incorporate microbial dynamics into grassland management and conservation strategies, aiming to sustain healthy and productive ecosystems by optimizing the ecological benefits of AM fungi and other soil microbes. The interaction effects between plant species and management on AM fungi, alongside the role of soil treatment in mediating these interactions, pointed to a complex relationship of environmental conditions, management practices, and species-specific traits in determining symbiotic relationship outcomes. The data presented in this thesis are crucial for developing sustainable management strategies that enhance plant productivity, soil health, and ecosystem resilience.

Date of Award	17 Jun 2024
Original language	English
Awarding Institution	The University of Manchester
Supervisor	David Johnson (Main Supervisor)