Data from: Parasites structuring ecological communities: the mistletoe footprint in Mediterranean pine forests

1. The capacity of parasitic plants in structuring natural communities is
increasingly recognized. These plants can affect the structure,
composition and productivity of plant communities by modifying the
competitive balance between hosts and non-host species and by altering the
quantity and quality of resources entering the soil. Despite the progress
made in this field, there is still a lack of integrative studies showing
the structuring capacity of parasitic plants in forest ecosystems, where
their effect may be less detectable due to the long lifespan of the
system. 2. In this study we evaluate the long-term impact of Viscum album
subsp. austriacum on the woody-plant community of a Mediterranean
pineland. This mistletoe remains several years on the same host, exerting
long-lasting, spatially concentrated effects on community and ecosystem
characteristics. Mistletoe concentrates zoochorous seeds and induces
changes in the soil fertility and light availability beneath the canopy of
parasitized trees, which have the potential to facilitate zoochorous-plant
colonization, recruitment, and growth at the same time as it weakens the
host. Here, we analyse whether mistletoe-driven changes could result in a
nucleus of zoochorous woody plants nourished by the abundant organic
detritus accumulated under the host. We also analyse whether mistletoe
effects can expand after host death. 3. We selected unparasitized,
parasitized, and dead parasitized Pinus nigra trees, in which we studied
the joint effect of mistletoe-mediated changes in soil nutrient and light
availability, with the seed rain, seed predation, seedling establishment,
plant recruitment, and plant growth. Light- and soil-nutrient resources
were greater under parasitized trees, and intensified after host death.
The seed rain was maximum under parasitized trees, where seedling
recruitment proved more likely. Sapling density, richness, and growth
increased with the development of parasitism. 4. Our findings show that
Viscum album exerts a strong and lasting impact on the structure and
dynamics of Mediterranean pinelands, with parasitized trees acting as
centres for the establishment and growth of colonizing fleshy-fruited
woody species, which, over the long term, promote vegetation shifts by
limiting dominant pine trees and facilitating less represented
fleshy-fruited shrubs.