摘要
种子的风传扩散是菊科入侵杂草的主要扩散方式之一,植物自身的传播特性和外在环境因子决定了种子扩散格局。从种子释放高度、沉降速度、脱落行为等内在因子出发,研究了两种在我国广泛分布的典型菊科入侵种小飞蓬和钻形紫菀自身的传播特性与风传扩散特征的关系。结果表明,小飞蓬和钻形紫菀的沉降速度均较小,分别为41.4cm·s-1和30.7cm·s-1,在空中停留时间长,且种子的脱落方式为非随机脱落,脱落概率大致与风速的平方成正比;种子的释放高度在种群内部存在很大的差异,显著影响种子的扩散距离。相比而言,小飞蓬种子的沉降速度大、释放高度高、远距离扩散(>100m)的概率大,扩散距离更远。研究表明了植物自身的传播特性对种子风传扩散的重要性,也为其他菊科入侵杂草种子风传扩散的研究提供了科学依据。
Seed dispersal by wind was a major process for invasive Asteraceae weeds to occupy new habitats,and quickly spread over their colonies.Internal and external factors,such as plant traits and environmental factors will determine seed dispersal direction,distance and seedling distribution.In this paper,we focused mainly on plant traits,such as release height,terminal velocity,shedding behavior,to study seed wind dispersal patterns of two invasive Asteraceae species,Conyza canadensis and Aster subulatus.Results showed that the terminal velocity of both C.canadensis（vt=41.4 cm·s-1） and A.subulatus（vt=30.7 cm·s-1） were slow,suitable for them to stay aloft in the air for potential long distance dispersal.Seed releasing heights of C.canadensis（120±38.48 cm） were higher than A.subulatus（100±26.97 cm）,with great variance excited among populations.Simulation of potential dispersal distance suggested that the average dispersal distance was 28 m and 19 m longer at the highest releasing height than the lowest for C.canadensis and A.subulatus,respectively.The probability of seed release was co-related with the square of horizontal wind velocity for both weeds.Results indicated that seed release of these two species were non-random,which increased the potential dispersal distance for seeds.About 0.015% and 0.002 5% of seeds were able to be long-distance dispersal（100 m） under non-random and random release condition for C.canadensis,and was 0.001 5% and almost none for A.subulatus.This paper suggested that plant traits were important for seed wind dispersal study and provided a way to study spread of other invasive Asteraceae weeds in China.
出处
《农业环境科学学报》
CAS
CSCD
北大核心
2011年第10期1978-1984,共7页
Journal of Agro-Environment Science
基金
国家自然科学基金(30771434)
浙江省科技厅公益性技术应用研究计划项目(2010C34003)
关键词
入侵杂草
种子脱落
释放高度
沉降速度
风传扩散
invasive weeds
seed release
release height
terminal velocity
wind dispersal
