  Mutualists and pathogens, collectively called symbionts, are ubiquitous in
plant communities. While some symbionts are highly host-specific, others
associate with multiple hosts. The outcomes of multispecies host-symbiont
interactions with different degrees of specificity are difficult to predict at
this point due to a lack of a general conceptual framework. Complicating our
predictive power is the fact that plant populations are spatially explicit, and
we know from past research that explicit space can profoundly alter plant-plant
interactions. We introduce a spatially explicit, stochastic model to
investigate the role of explicit space and host-specificity in multispecies
host-symbiont interactions. We find that in our model, pathogens can
significantly alter the spatial structure of plant communities, promoting
coexistence, whereas mutualists appear to have only a limited effect. Effects
are more pronounced the more host-specific symbionts are.
