The effect of plant-fungi interaction generalism on plant community productivity
Authors:   , Thomson-Laing Jacob 
Published: December 2021

<p>Plant-plant productivity relationships within ecosystem and community ecology are contentiously debated in the literature due to the numerous factors involved making conclusions hard to draw and disentangle. There are several widely established and supported plant-plant productivity relationships. Increasing species richness can allow for greater niche complementarity, which in turn increases overall above and below ground productivity. Plants with different functional traits can differentially affect a plant community depending on the arrival time of the plant. These priority effects allow certain plants to outcompete others and persist in a community across different temporal scales. Plant species differ in their ability to interact with certain species of symbiotic partners in the soil (Arbuscular mycorrhizal fungi, AMF). This interaction generalism of a plant species indicates the ability of a plant to host many or few AMF species (generalist or specialist, respectively). However, there remains a limited understanding of plant-fungi relationships especially with respect to community productivity and the temporal effects of adding contrasting types of interaction generalism into an established community. The aim of this study was to determine the effects of the addition of an interaction specialist or generalist plant species into an established plant community on the overall community productivity. Three communities that differed in plant species richness were grown for 38 days at which point either a generalist or specialist was added. Community treatments were carried out in field soil, sterile soil and sterile soil reinoculated with viable field soil, separating the effects of plant niche-partitioning for plant-fungi interaction partners from the effects of niche-partitioning for other resources (e.g. soil nutrients). Community productivity was tested using different productivity measures; 1) carbon flux as the Net Ecosystem Exchange (NEE) of the community, 2) total above and below ground plant biomass, 3) neutral lipid fatty acid (NLFA) AMF biomarker, 16:1w5, extracted from total soil and total root mass to assess AMF biomass. It was difficult to disentangle the effects of species richness and interaction generalism on carbon flux in communities, with soil type clearly impacting these relationships. In all soil types, an increase in community plant richness had the greatest effect on carbon draw down and biomass productivity with respect to both plant and AMF biomass. In non-sterilised soil, interaction generalism, specifically the addition of a specialist alongside increased species richness corresponded to increased carbon drawdown. In the context of previous research, this study further highlighted the complexity of factors driving plant-plant-fungi relationships, but clearly identifies the positive role that species richness is having. Although the role of plant-fungi relationships in overall community productive remains unclear, this study provides a platform for future research to be undertaken.</p>