入侵与本地菊科植物种子功能特征差异及其对局域扩散的影响

Differences in seed functional traits between invasive and native Asteraceae plants and their effects on local dispersal patterns

关键词:  菊科, 入侵植物, 种子形态特征, 冠毛特征, 种子扩散

Key words:  Asteraceae, invasive plants, seed morphological traits, pappus characteristics, seed dispersal

摘要:

为探究菊科种子(瘦果)形态和功能特征对植物扩散的影响,该文以哀牢山区的9种类型同为瘦果的菊科植物(5种入侵植物、4种本地植物)为研究对象,采用样方法测定了道路沿线各物种的密度和频度,并分别测定了各供试植物的沉降速度、冠毛半径、冠毛长度、种子长度、种子宽度、种子质量、种子萌发率和冠毛载荷。结果表明:(1)在调查道路的沿线,物种出现频度的差异主要在物种间,入侵植物和本地植物类型间没有差异,而在植株密度方面入侵植物则显著高于本地植物。(2)在种子特征方面,入侵植物的种子萌发率显著大于本地植物,但其余种子的特征变化主要在物种间。(3)相关性分析显示,种子萌发率和种子质量没有明显的相关性,而种子沉降速度与种子长宽和冠毛载荷存在显著关联。(4)种子特征之间的相关关系在入侵植物和本地植物间不同,如在本地植物之间,种子萌发率和沉降速度呈负相关,但在入侵植物中缺乏这样的权衡关系,暗示入侵植物和本地植物种子生态策略的差异。(5)在所有供试菊科植物中,物种密度与种子萌发率呈显著正相关,但物种出现频度与种子特征之间没有明显的相关关系。这表明种子的形态特征能显著影响种子扩散潜力,但并不能完全反映实际扩散效果,菊科入侵植物更高的种子萌发率是其在野外能形成高密度群丛的一个重要原因。

Abstract:

To investigate the effect of Asteraceae seed(achene)morphology and functional traits on plant dispersal, we selected nine Asteraceae species(five invasive species and four native species)from the Ailao Mountain area as study species. We measured the density and frequency of each species along roads in the study site using a plot method.Furthermore, settling velocity, pappus radius, pappus length, seed length, seed width, seed mass, seed germination rate, and pappus loading of each species were measured. The results were as follows:(1)Along the surveyed roads, differences in species frequency were primarily observed among species with no significant differences between invasive and native species; however, invasive plants exhibited significantly higher plant densities compared to native plants.(2)Regarding seed traits, invasive plants had a significantly higher germination rate than native plants, while variations in other seed traits were predominantly species-specific.(3)Correlation analysis showed that no significant correlation was found between seed germination rate and seed mass, whereas seed sedimentation velocity was significantly correlated with seed length and width, and pappus loading.(4)Correlations between seed traits differed between invasive and native plants. For instance, among native species, seed germination rate was negatively correlated with sedimentation velocity, but this trade-off was not observed in invasive species, indicating differing seed ecological strategies between invasive and native plants.(5)For all tested Asteraceae plants, species density was significantly positively correlated with seed germination rate, and no significant correlation was found between species frequency and seed traits. These results suggest that seed morphological traits significantly influence seed dispersal potential, yet they do not fully reflect the actual dispersal outcomes. The higher seed germination rates of invasive Asteraceae plants is an important reason for their high field density formation.