Shrub leachates rich in soluble phenols negatively affect the germination of dominant perennial grasses and shrubs in the Patagonian Monte

Grazing reduces grass cover and promotes the dominance of shrubs with high concentration of soluble phenols, which may leach from their canopies and reach neighboring plants and soils. Despite their potential allelopathic effects, these interactions remain poorly studied in arid ecosystems. Our aim was to analyze the effects of leachates from shrub canopies with high concentration and diversity of soluble phenols, and shrub-associated soils on germination of perennial grasses and conspecific shrub propagules. We sowed propagules of dominant perennial grasses and shrubs in separated Petri dishes containing soil from shrub patches. Propagules were moistened with water (control) or leachates from canopies dominated by shrubs with different phenolic profiles. Shrub leachates reduced shrub germination and increased the mean germination time of perennial grasses and shrubs. The strongest inhibitory effects were associated with complex phenolic profiles, indicating that allelopathic effects depended on shrub compound complexity. Our results suggested that increased mean germination time may expose late-emerging seedlings to low resource availability during the later stages of the growing season, along with increased exposure to negative allelopathic effects, not only from shrubs on perennial grasses, but also among shrubs. These results highlighted the importance of allelopathic interactions in arid ecosystems affected by grazing. Fil: Muñoz, Giovana Magali. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Centro Nacional Patagónico. Instituto Patagónico para el Estudio de los Ecosistemas Continentales; Argentina Fil: Carrera, Analía Lorena. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Centro Nacional Patagónico. Instituto Patagónico para el Estudio de los Ecosistemas Continentales; Argentina. Universidad Nacional de la Patagonia "San Juan Bosco"; Argentina