摘要：Clarifying the effects of climate warming on seed germination is critical for predicting plant community assembly and species renewal, especially in alpine grassland ecosystems where warming is occurring faster than in other biomes globally. We collected matured seeds of 19 common species from a typical alpine meadow steppe community in Central Tibet. Seeds were germinated in three incubators with manipulated day-night temperatures to impose three treatments: (1) theoretically optimal values of 25/15 #176;C, (2) temperatures observed in the field (control), and (3) a warming of 3 #176;C above the observed temperatures. We calculated seed germination percentage (SGP) and mean germination time (MGT) per species at different treatments. Our results showed that SGPs of iStipa capillacea/i, iKobresia macrantha/i, iPotentilla saundersiana/i, iSaussurea tibetica/i, iPedicularis kansuensis/i, and iAndrosace graminifolia/i were higher under the warming treatment than under control. Among them, the MGTs of iS. capillacea/i, iK. macrantha/i, and iAnd. graminifolia/i were significantly shortened, while the MGT of iPe. kansuensis/i was significantly lengthened by warming of 3 #176;C. Significant decreases in MGT induced by warming were only observed for iFestuca coelestis/i and iAnaphalis xylorhiza/i. Additionally, the treatment with theoretically optimal temperatures restrained germination of iStipa purpurea/i, iS. capillacea/i, iF. coelestis/i, and iSa. tibetica/i seeds but promoted germination of iK. macrantha/i, iAstragalus strictus/i, iP. saundersiana/i, iPotentilla bifurca/i, iPe. kansuensis/i, iSwertia tetraptera/i, iPleurospermum hedinii/i, and iAnd. Graminifolia/i seeds, when compared with the control and warming treatments. Therefore, the response of seed germination to warming differs among alpine species, implying that future warming could result in significant changes in community assembly of alpine grasslands on the Tibetan Plateau.
