Plant movements and climate warming: intraspecific variation in growth responses to non-local soils
Mouvements des plantes et réchauffement climatique : variations intra-spécifiques de la croissance en réponse aux sols non-locaux
Résumé
Most range shift predictions focus on the dispersal phase of the colonization process. Since moving populations experience increasingly dissimilar non-climatic environmental conditions as they track climate warming, it is also critical to test how individuals originating from contrasting thermal environments can establish in non-local sites. We assess the intraspecific variation in growth responses to non-local soils by planting a widespread grass of deciduous forests (Milium effusum) into an experimental common garden using combinations of seeds and soil sampled in 22 sites across its distributional range, and reflecting movement scenarios of up to 1600 km. Furthermore, to determine temperature and forest-structural effects, the plants and soils were experimentally warmed and shaded. We found significantly positive effects of the difference between the temperature of the sites of seed and soil collection on growth and seedling emergence rates. Migrant plants might thus encounter increasingly favourable soil conditions while tracking the isotherms towards currently 'colder' soils. These effects persisted under experimental warming. Rising temperatures and light availability generally enhanced plant performance. Our results suggest that abiotic and biotic soil characteristics can shape climate-change driven plant movements by affecting growth of non-local migrants, a mechanism which should be integrated in predictions of future range shifts.