Seed germination characteristics and their influencing factors in alpine/subalpine meadow plants

Seed germination is a critical stage in the life of plants that strongly affects species establishment, interspecific coexistence, and community structure. We chose 104 common plant species from an alpine/subalpine meadow on the eastern edge of the Tibetan Plateau to conduct germination experiments and investigate the factors affecting their germination characteristics. The results showed that the germination behavior was strongly controlled by phylogeny. The taxon family could explain 50.74%, 35.22%, 19.68%, 16.57%, and 37.92% of the variation in germination percentage (GNP), mean germination time (MTG), germination uncertainty (UNC), germination synchrony (SYN), and germination variability (CVG), respectively. The germination characteristics of alpine/subalpine meadow plants were also affected by life history: The MTG of perennials was 5.21 d longer and UNC was 0.73 higher than that of annuals. When the seed size increased by 1 mg, the MTG was prolonged by 1.07 d, the UNC increased by 0.14, and SYN decreased by 0.03. Among the small-, middle-, and large-size species, the GNP, UNC, and CVG of large-size species were higher, but their SYN was lower. In addition, the GNP and MTG of the widely distributed species on the elevation gradient were 6.89% higher and 1.20 d shorter than those of the narrowly distributed species, respectively. In alpine/subalpine meadow communities, phylogeny is an important constraint that determines seed germination characteristics. Species cope with unpredictable environments by adopting different germination strategies, such as opportunistic rapid synchronous or asynchronous bet-hedging germination strategies.