Temporal dynamic of parasite-mediated linkages between the forest canopy and soil processes and the microbial...

Parasitic plants are important drivers of community and ecosystem properties. In this study, we identify different mechanisms by which mistletoe (Viscum album subsp. austriacum) can affect soil chemical and biological properties at different temporal stages of parasitism. We quantified the effect of parasitism on host growth and the number of frugivorous mutualists visiting the host canopy. Then we collected, identified, and weighed the organic matter input underneath tree canopies and analyzed its nutrient content. Simultaneously, we analyzed soil samples under tree canopies and examined the chemical properties, microbial abundance, and functional evenness of heterotrophic microbial communities. Mistletoe increased the amount, quality, and diversity of organic matter input beneath the host canopy, directly through its nutrient-rich litter and indirectly through a reduction in host litterfall and an increase in bird-derived debris. All these effects gave rise to enriched hotspots able to support larger and more functionally even soil microbial communities beneath parasitized hosts, the effects of which were accentuated after host death. We conclude that mistletoe, together with the biotic interactions it mediates, plays a key role in intensifying soil resource availability, regulating the functional evenness, abundance, and spatial distribution of soil microbial communities.