PARENT SESSION
Symposium 2: Soil Biodiversity: Scaling from microbe to ecosystem
Organized by: A Fitter, C Kennan, and H Jones
Monday, August 8, 8:00 AM - 11:30 AM, Meeting Room 517 B, Level 5, Palais des congrès de Montréal
Plant-soil feedbacks during exotic plant invasions reflect biogeographic decoupling of plants and soil biota.
Callaway, Ragan*,1, Hawkes, Christine2, 1 Division of Biological Sciences, Missoula, Montana, USA2 Section of Integrative Biology, Austin, Texas, USA
ABSTRACT- Evidence is increasing for the important role of soil biota in exotic invasions. Invaders may escape inhibitory biota, encounter facilitative biota, or alter soil microbial processes in invaded ecosystems, particularly when traditional biogeographic barriers are overcome. We find that plant soil feedback processes shed light on several exotic invasions between Europe and North America. Centaurea maculosa, a European invader of North America, and Prunus serotina, an American invader of Europe, participate in different plant soil feedback processes at home compared with their introduced ranges. In native soils, these invaders cultivate soil biota with increasingly negative effects on their growth, possibly leading to their control. But in soils from invaded ranges, Centaurea and Prunus cultivate soil biota with increasingly positive effects on themselves, which may contribute to the dramatic increase in ecological success that these species experience in their new ranges. These patterns were further confirmed in a range of exotic, native, and hybrid Senecio species in the UK. Introduced Senecio harbored significantly fewer soil-borne pathogens and greater mycorrhizal colonization regardless of time since invasion, which led to improved survival and reproduction compared to UK-native Senecio. In their introduced range in California, Senecio vulgaris also had lower rates of soilborne pathogen attack and belowground root lesions compared to their native UK range. We attribute these biogeographic differences to pathogen plant relationships that are more host specific than mutualist plant relationships. The feedback loops that develop between soil biota and an invasive plant may depend on the biogeographical source of the microbes.
Key words: soil biota, exotic invasions, soil feedbacks