Linking above and below-ground interactions in agro-ecosystems: An ecological network approach
Ecological networks are formed from the species present within communities and the interactions between them. The structure of these networks determine the nature of services provided to the ecosystem. Until recently, few studies attempted to link below-ground species interactions to above-ground interactions, with even fewer focusing on commercially important crop species, the cascading effects of altered network structures, or how the inherent traits of plant genotypes shape the resulting network. Arbuscular mycorrhizal fungi (AMF) have the potential to influence both plant floral traits, which may impact the attraction of pollinators and shape the resulting plant-pollinator network, as well as plant reproductive factors, which may influence the quantity and quality of crop yields. The influence of AMF and plant genotype on pollinator visitation rates, community structure, and yield was examined using three genotypes of strawberry plants, and four AMF treatments. We measured pollinator visitation and community composition by running field transects, and collected strawberries to determine yield quantity and quality. Additionally, we measured a range of plant floral traits to understand the fundamental biology behind the effects we observed. The study was run over a two year period, with the experiment mirrored between the field and greenhouse.
Overall, plant genotype was found to have the largest impact, resulting in significant changes in strawberry yield. AMF showed a trend to influence yield, though the results were equivocal, with the direction and strength of the interaction dependant on the specific combination of plant genotype and AMF community. Strawberry yield and the number of pollinator visits was found to be correlated for two of the three plant genotypes. In terms of floral traits, flowering phenology, flower size, pollen and nectar quantity, were influenced most strongly by plant genotype, with the influence of AMF again depending on the specific combination of AMF community and plant genotype. Data from the plant-pollinator network is currently being analysed. These results indicate that plant / pollinator interactions can be mediated by the inherent traits of the genotype of plant species studied, with a trend for AMF to influence the resulting yields. With increasing pressures on crop production, both through declines in pollinator communities and the cost and availability of agrochemicals, research into this field may form part of an important toolset for sustainable increases in food security, as well as helping us to gain a deeper understanding of the fundamental biology that influences ecological networks.