Arbuscular mycorrhiza has little influence on N2O potential emissions compared to plant diversity in experimental plant communities

ABSTRACT Denitrification is an ecosystem process linked to ongoing climate change, because it releases nitrous oxide (N2O) into the atmosphere. To date, the literature covers mostly how aboveground (i.e. plant community structure) and belowground (i.e. plant-associated soil microbes) biota separately influence denitrification in isolation of each other. We here present a mesocosm experiment where we combine a manipulation of belowground biota (i.e. addition of Rhizophagus irregularis propagules to the indigenous mycorrhizal community) with a realized gradient in plant diversity. We used a seed mix containing plant species representative of mesophytic European grasslands and by stochastic differences in species establishment across the sixteen replicates per treatment level a spontaneously established gradient in plant diversity. We address mycorrhizal-induced and plant-diversity mediated changes on denitrification potential parameters and how these differ from the existing literature that studies them independently of each other. We show that unlike denitrification potential, N2O potential emissions do not change with mycorrhiza and depend instead on realized plant diversity. By linking mycorrhizal ecology to an N-cycling process, we present a comprehensive assessment of terrestrial denitrification dynamics when diverse plants co-occur.

Shroomroot: An Action-Based Digital Game to Enhance Postsecondary Teaching and Learning about Mycorrhizae

The majority of terrestrial plants associate with fungi in symbiotic resource-exchange relationships called mycorrhizae. Because of the importance of these mycorrhizal systems to ecosystem functioning, it is crucial that future resource managers and scientists have a solid understanding of mycorrhizal ecology. Limited interest of postsecondary students in plants and fungi compared with animals, combined with difficulties visualizing below-ground processes, present challenges for learning mycorrhizal concepts. To address this, we created the digital, plant-ecology-centric, action-based game Shroomroot for use in a second year, postsecondary Introduction to Soil Science course. We then assessed effects of Shroomroot on students’ knowledge acquisition and engagement with the topic of mycorrhizal ecology using a pre- and post-test evaluation. Students’ knowledge of mycorrhizal ecology increased significantly after playing Shroomroot, and tended to increase more for items related to Shroomroot gameplay than in rewards-based game content. Student engagement with mycorrhizal content tended to increase after gameplay. These results suggest positive potential for action-based, plant-ecology-oriented digital games in a postsecondary science curriculum. Furthermore, greater understanding of mycorrhizae has the potential to improve our multifaceted relationships with the ecosystems upon which we depend.

Mycorrhizal Ecology

Mycorrhizae are ubiquitous in terrestrial ecosystems. With an increasing awareness that this symbiotic association plays important roles in plant population dynamics, community structures and ecosystem functioning, mycorrhizal ecology has emerged as a fast growing subdiscipline in the field of ecology. Over recent decades, studies have expanded from descriptions of basic mycorrhizal biology to investigations of their functional relevance in a broader ecological context. Today’s research is dominated by the search for underlying mechanisms and general principles. The readings on issues related to mycorrhizal ecology include basic overviews of mycorrhizal studies, classification and species diversity, methodology in mycorrhizal examination, costs and benefits, population and community ecology of mycorrhizae, their ecological significance in plant community and ecosystem, multitrophic interactions, and practical applications. This bibliography focuses on the most widespread and ecologically important types of mycorrhizae—arbuscular mycorrhizae and ectomycorrhizae.

Suppression of fungal and nematode plant pathogens through arbuscular mycorrhizal fungi

Arbuscular mycorrhizal (AM) fungi represent ubiquitous mutualists of terrestrial plants. Through the symbiosis, plant hosts, among other benefits, receive protection from pathogens. A meta-analysis was conducted on 106 articles to determine whether, following pathogen infection of AM-colonized plants, the identity of the organisms involved (pathogens, AM fungi and host plants) had implications for the extent of the AM-induced pathogen suppression. Data on fungal and nematode pathogens were analysed separately. Although we found no differences in AM effectiveness with respect to the identity of the plant pathogen, the identity of the AM isolate had a dramatic effect on the level of pathogen protection. AM efficiency differences with respect to nematode pathogens were mainly limited to the number of AM isolates present; by contrast, modification of the ability to suppress fungal pathogens could occur even through changing the identity of the Glomeraceae isolate applied. N-fixing plants received more protection from fungal pathogens than non-N-fixing dicotyledons; this was attributed to the more intense AM colonization in N-fixing plants. Results have implications for understanding mycorrhizal ecology and agronomic applications.