【作者】 卜海燕；

【导师】 杜国祯；

【作者基本信息】 兰州大学 ， 生态学， 2007， 博士

【摘要】 自从Theophrastus(372-287 B．C．)开始研究种子的萌发之后，关于种子萌发的信息越来越多。然而，长期以来，有关种子萌发能力的研究多集中在同一物种范围内，而不同物种间的比较研究却不多，而且大多仅限于几个物种或者某一个属的物种间比较，对于整个群落的物种间萌发与休眠比较也就更少了，但是在同一物种内的研究结果并不足以说明种子萌发能力的生态学意义。而且，对群落范围上已经开展的少数研究都集中在热带或温带地区，对于高寒草甸这一特殊生境的研究还是一片空白。因此，本研究中对青藏高原东部高寒草甸中的常见植物的种子萌发能力进行了较为系统的研究，可以说是物种间种子萌发能力研究的重要补充。我们期望通过我们的研究为探讨青藏高原东部高寒草甸的物种组成以及整个生态系统的动态变化提供最基础的理论依据。我们的研究结果表明：1)本研究所用的633个物种中，66个物种自始至终没有萌发，超过一半的物种萌发百分率没有达到20％，物种休眠的主要类型为生理休眠。根据种子的萌发特性，种子的萌发类型可以分为爆发型、过渡型、缓萌型和低萌型四种。2)不同海拔梯度之间，种子萌发百分率差异显著，随着海拔的升高，平均种子萌发百分率逐渐降低，而萌发开始时间与海拔相关不显著；物种的休眠比例差异也不显著。3)不同生境之间，种子萌发能力和休眠比例差异不显著，但是从阳坡采集到的种子的萌发百分率、萌发开始时间均为最高；阳坡具有最低的休眠比例，阴坡具有最高的休眠比例。4)不同生活型、植物生活周期以及种子扩散方式之间，种子萌发能力差异显著，其中，木本植物萌发百分率最低，休眠比例最高，而禾草类植物萌发百分率最高，休眠的比例最少；多年生植物萌发百分率较高，一年生植物的休眠比例稍高一些；随着物种扩散能力的增强，物种的萌发百分率增高，物种的休眠比例降低；5)种子萌发百分率与种子大小呈显著负相关，萌发开始时间与种子大小呈显著正相关。6)不同科间种子萌发能力差异显著。物种休眠比例较低的科大多集中在系统发育树较高的位置，而那些物种休眠比例较高的科则多集中在系统发育树较低的位置。7)综合探讨影响种子萌发与休眠的因素，我们发现，系统发育对解释平均种子萌发时间变异的贡献最大(25％)，其它几个生活史特征因素一共只能解释平均萌发时间变异的7％；此外，大部分系统分类群与海拔(和生境)之间存在显著的交互作用，这些交互作用的效应说明本区系内种子萌发时间变异的系统发育控制力与环境条件有关系。因此，我们认为，青藏高原东部高寒草甸植物种子萌发能力变异受到系统发育史、生活史背景以及环境因素的共同控制。我们在探讨物种间种子萌发能力变异的时候，应该同时考虑生态因素与系统发育史的影响，而不能有意将其分开。更多还原

【Abstract】 Since the days of Theophrastus (372-287 B.C.) , a vast amount of information related to seed germination has accumulated. However, most of the literature investigated seed germination within one species, and the less paid attention to the difference among species. Furthermore, most comparison in seed germination among species only limited to compare among several species or within a genus, and the comparative studies on seed germination and dormancy in a whole community were much less. But the comparative results derived from one or several species didn’t account for the ecological significance of seed germinability. In addition, the studies reported on seed germination within a community were done in tropical or temperate zone, and there was not investigation on alpine meadow. Thus, we investigated the seeds germinability of species in an alpine meadow on the eastern Qinghai-Tibet plateau, which might be the important supplement to the field on inter-specific seed germinability. We expected to provide the basic theoretic evidence by our study on discuss the species composition and dynamic of ecosystem in the alpine meadow on the eastern Qinghai-Tibet plateau.The results showed: 1) Among the studied 633 species, 66 species did not germinate, over half of the species were dormant, and physiological dormancy was the most important; according to the seed germination characteristics, the species were divided into 4 distinct groups: rapid, slow, intermediate (percent germination > 50%) and low germinating(percent germination <50%). 2) There was significant difference in percent germination among altitudes, but not significant in days to first germination and dormant proportion of species; and there was significant negative correlations between percent germination and altitudes. 3) There was not significant difference in seed germinability and dormant proportion of species among habitats, however, species from south slope had the highest percent germination, the earliest days to first germination and the lowest dormant proportion of species, and species from north slope had the highest dormant proportion of species. 4) There was significant difference in seed germinability among life form, perenniality and seed dispersal mode. The woody plants had the lowest percent germination and the highest dormant proportion, and the graminoid plants had the adverse results; the annuals had higher dormant proportion and lower percent germination; increasing percent germination and decreasing dormant proportion were going with increasing dispersal; 5) There was significant negative correlation between percent germination and seed size, and significant positive correlation between days to first germination and seed size; 6) There was significant difference among families. Furthermore, there was a trend that most species with lower dormant proportion were concentrated in families in the upper portion of the phylogenetic tree, and most species with higher dormant proportion were in the lower position of the phylogenetic tree; 7) In summary, phylogenetic relatedness had the greatest contribution to the variation in mean germination time (25%), and all the life-history traits could explained only 7% of the variation in mean germination time among the species in the alpine meadow. In addition, there was significant interactions between phylogenic groups and altitudes (or habitats), which could be considered that the phylogenetic constraints on seed germinability also related to environment conditions. Thus, seed germination and dormancy in the alpine meadow on the eastern Qinghai-Tibet plateau were affected by phylogenetic, life-history and environment factors. The ecological and phylogenetic factors should be taken into account when we discussed the difference of species.更多还原