One does not simply grow well: Performance of grassland plants in home and foreign soil and climate

O_LIPlant-soil feedbacks (PSF) play a substantial role in determining plant performance in native and foreign habitats. Yet, PSF strength may be altered by climatic parameters, creating synergies. Here, we assess performance of alpine grassland species in their native and in foreign soils in an experiment including different climates. C_LIO_LIUsing soil and seeds sampled from six alpine grassland sites spreading in a gradient from Northern Africa to Northern Europe, we compared plant performance in home soil and in five foreign soils, as well as home and foreign climates (simulated temperature and photoperiod in growth chambers). C_LIO_LIWe found that despite a high variability in plant performance between sites, plants generally performed better in their home soil and home climate, than in foreign soil or in foreign climate. However, an interaction between soil and climate effect caused this better performance in home soil to occur only when in foreign climate. Similarly, performance improved in home climate only when plants were also placed in foreign soil. C_LIO_LISynthesis: In contrast to predictions from the literature, no benefit from growing in foreign soils are indicated. At least on the short term, climate change alone is not suggested to affect native grassland plant performance. However, when introduced to a habitat with a similar climate to their native habitat, plants may perform as well as in their native range, but when introduced both to a new soil and climate, plants will do poorly. This finding sheds light on the interactive effect of climate and soil origin, as well as the possible success of plant introductions under a changing climate. C_LI