高寒/亚高寒草甸植物种子萌发特性及其影响因素

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

种子萌发是植物生活史的关键阶段,强烈影响着物种建植、种间共存和群落结构。本研究选取青藏高原东缘高寒/亚高寒草甸为研究区,选择104种常见植物开展萌发试验,探讨种子萌发特性的影响因素。结果表明,高寒/亚高寒草甸植物种子的萌发行为受到系统发育的强烈控制,科分类单元分别能够解释50.74%、35.22%、19.68%、16.57%和37.92%的萌发率、萌发时间以及萌发不确定性、同步性和变异性。高寒/亚高寒草甸植物的萌发特性还受到生活史特征的影响:多年生植物的平均萌发时间比一年生植物长5.21 d,不确定性高0.73;种子大小每增加1 mg,平均萌发时间延长1.07 d,萌发不确定性升高0.14,同步性降低0.03;在小株、中株、大株3类株高中,大株植物的萌发率、萌发不确定性及变异性较高,同步性较低。此外,海拔梯度上的广布种的平均萌发率比狭布种高6.89%,平均萌发时间短1.20 d。在高寒/亚高寒草甸植物群落中,系统发育是决定种子萌发特性的重要约束条件,物种通过采取快速同步萌发的机会主义对策、“两头下注”的异步萌发对策等不同的萌发策略应对不可预测环境。

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.