UBC Theses and Dissertations
The effect of grazing on arbuscular mycorrhizal fungi in temperate grasslands van der Heyde, Mieke Elisabeth
Managed grazing, involving large animals destined for human consumption, covers more than 25% of the land surface and has the capacity to alter ecosystems, often leading to desertification, woody encroachment, and deforestation (Asner et al 2014). Arbuscular Mycorrhizal (AM) fungi are ubiquitous root symbionts that colonize 80% of terrestrial plants and influence plant productivity and community composition. Despite the importance of AM fungi for plant communities, the effect of grazing on AM fungal communities is largely unknown. I used grazing exclosures of varying ages to compare AM fungal community and infectivity in grazed and ungrazed plots, as well as several environmental variables that may be affected by grazing. AM fungal community composition was not significantly different between grazed and ungrazed, but grazing increased spore density while decreasing soil hyphal length. This may be attributed to the plasticity of AM fungi in response to environmental conditions, flexibility allowed isolates to respond to grazing without shifting community composition. None of the environmental variables was related to the change in AM fungi, indicating that variables not measured may be responsible. Time since the exclosure was established was the only variable related to community dissimilarity between grazed and ungrazed. As the age of the exclosure increased, the dissimilarity also increased, highlighting the importance of long-term studies in furthering our understanding of grazer-fungi interactions.
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