The emerging science of linked plant–fungal invasions

Abstract

Contents 1314I.1315II.1316III.1322IV.1323V.1325VI.1326VII.1326VIII.13271328References1328 Summary Invasions of alien plants are typically studied as invasions of individual species, yet interactions between plants and symbiotic fungi (mutualists and potential pathogens) affect plant survival, physiological traits, and reproduction and hence invasion success. Studies show that plant–fungal associations are frequently key drivers of plant invasion success and impact, but clear conceptual frameworks and integration across studies are needed to move beyond a series of case studies towards a more predictive understanding. Here, we consider linked plant–fungal invasions from the perspective of plant and fungal origin, simplified to the least complex representations or ‘motifs’. By characterizing these interaction motifs, parallels in invasion processes between pathogen and mutualist fungi become clear, although the outcomes are often opposite in effect. These interaction motifs provide hypotheses for fungal‐driven dynamics behind observed plant invasion trajectories. In some situations, the effects of plant–fungal interactions are inconsistent or negligible. Variability in when and where different interaction motifs matter may be driven by specificity in the plant–fungal interaction, the size of the effect of the symbiosis (negative to positive) on plants and the dependence (obligate to facultative) of the plant−fungal interaction. Linked plant–fungal invasions can transform communities and ecosystem function, with potential for persistent legacies preventing ecosystem restoration.

Biodiversity of arbuscular mycorrhizal fungi and ecosystem function

“…There are many types of novel environments to consider for manipulative experiments in the present and future. These include invaded systems (Dickie et al ., ); marginal soils opened up for agriculture with the increasing pressure to feed a growing population; degraded systems that are to be restored (Asmelash et al ., ); systems in which climate change facilitates range expansion by AM fungi and their hosts (Smith, ; Newsham et al ., ); and green roofs and other urban/technological environments up to high‐tech glasshouses and horticultural settings. These latter instances will probably increase in importance, and data on AM functional contributions and diversity in such human‐made systems is mostly unavailable (green roofs: John et al ., ).…”

Land use is a determinant of plant pathogen alpha‐ but not beta‐diversity

“…In natural ecosystems they are known to enhance the diversity of forests and grasslands (the Janzen‐Connell and the dilution effect hypotheses; Janzen, ; Keesing, Holt, & Ostfeld, ) and shape the succession of vegetation (Van der Putten, Van Dijk, & Peters, ). Invasive pathogens can have large effects on agricultural systems and alter entire ecosystems (Dickie et al, ). Despite their importance, very little is known about large‐scale diversity patterns of plant pathogens (Burgess et al, ).…”

Sharing resources for mutual benefit: crosstalk between disciplines deepens the understanding of mycorrhizal symbioses across scales

“…Marcel van der Heijden (Agroscope and University of Zurich, Switzerland) used network imagery to show how different farming systems (organic vs conventional) shift microbial co‐occurrence networks in ways that affect their function. Ian Dickie (University of Canterbury, New Zealand) used a network approach to show that many exotic tree species in New Zealand tend to interact with a distinct set of fungi compared with native tree species (Dickie et al ., ,b).…”