【作者】 常瑞英；

【导师】 刘建；

【作者基本信息】 山东大学 ， 环境科学与工程， 2013， 硕士

【摘要】 生物入侵已成为全球变化的重要组成部分,并在人类干扰和全球气候变化的影响下日益加剧。生物入侵会干扰新栖息地生态系统结构和功能稳定性,降低当地物种的生物多样性,同时阻碍经济发展和危害人类健康。空心莲子草(Alternanthera philoxeroides (Mart.) Griseb.)是世界性的恶性入侵植物,已成为我国湿地的重要入侵种,造成严重的生态危害和经济损失。尤其在富营养分化水体中,空心莲子草能在短时期内迅速繁殖,形成大面积单种群落,给当地的生物多样性和湿地生态系统服务功能带来严重威胁。氮磷元素作为植物最重要的营养元素,对空心莲子草的生长具有重要影响。研究不同养分水平和氮磷比,对空心莲子草生长的影响,及对空心莲子草与非入侵种的种间竞争关系的影响,对于揭示空心莲子草的入侵机制具有重要意义,同时为空心莲子草的防治提供科学依据和建议。本研究通过温室实验,研究了不同养分水平和氮磷比条件下,空心莲子草的生长指标及与非入侵种竞争关系的变化。实验中设置低、中、高3个养分水平,同时每个养分梯度下设置3个氮磷比(1、10、100)。实验材料采用3个物种,分别为入侵植物空心莲子草(Alternanthera philoxeroies)、本地植物水芹(Oenanthe javanica)及外来非入侵植物黄菖蒲(Iris pseudacorus),采用单种和混种的种植方式,研究不同养分处理对空心莲子草及与其他2种非入侵植物的种间竞争关系的影响。空心莲子草的单种实验结果表明,养分水平和氮磷比对空心莲子草的生物量积累、形态特性、光合荧光及叶片氮磷含量均有显著影响。高养分水平显著地增加了空心莲子草的生物量积累、分枝数、分蘖数、匍匐茎长。氮磷比对空心莲子草植物地上部分,如分枝数、分蘖数、匍匐茎长等有显著影响,而对其生物量分配无显著影响。空心莲子草的比叶面积随着养分水平的升高显著地减低,在高养分下,具有最低的比叶面积；同时,在同一养分水平下,比叶面积随着氮磷的降低而显著增加,在氮磷比为1的条件下,具有最高的比叶面积。空心莲子草与2种非入侵植物的混种实验结果表明,在不同的养分条件下,空心莲子草具有比其他2个物种更高的表型可塑性,对环境的适应性较强。入侵种空心莲子草对养分水平的响应更为敏感,同时对氮磷比的响应快于其他2个物种,从而更好的促进自身生长和竞争能力。不同的养分条件下,入侵种空心莲子草的比叶面积具有较高的表型可塑性,而本地种水芹的比叶面积表型可塑性较低。空心莲子草叶片具有.比其他2个物种更高的氮磷含量,表明该物种具有较强的氮磷吸收能力,对高养分生境的适应性强。在入侵种空心莲子草与2种非入侵植物混种实验中,空心莲子具有绝对的竞争优势,高养分环境下空心莲子草的竞争优势更大,而低养分环境往一定程度上能降低空心莲子草的竞争优势。氮磷比对空心莲子草的竞争优势的影像随着养分总体水平不同而变化,在中养分条件下,磷元素让空心莲子草入侵的过程中扮演着重要角色,而在低和高养分下,氮磷比对该物种的入侵没有显著影响。总之,养分水平和氮磷比对空心莲子草及其与其他2个非入侵种的竞争关系均有显著影响,空心莲子草可塑性强,且对高养分环境更为适应。研究结果有助于揭示空心莲子草的入侵机制和预测环境变化对其未来入侵趋势的影响,同时为空心莲子草的防治工作提供科学依据和建议。更多还原

【Abstract】 Biological invasion has been an important part of global changes, and might aggravate under the influence of human disturbance and global climate change. Biological invasion might have serious influence on the ecosystem structure and functional stability, reducing the diversity of local species, hampering the economic development, and harming to people’s health. Alligator weed (Alternanthera philoxeroies (Mart.) Griseb) is a worldwide noxious invasive plant and has become a major invader of wetland habitats in China, causing serious ecological damages and economic losses. In the eutrophication wetland, A. philoxeroides could spread rapidly and form dominant species in large areas, which pose a serious threat to local biodiversity and wetland ecosystem service function. Nitrogen and phosphorus, considered as the most important nutrient elements for plant growth, has significant effect on the growth of A philoxeroies. The research on the effects of nutrient level and N:P ratio on growth of A. philoxeroies and the competition between A. philoxeroies and non-invasive species, could play an important role in revealing the invasive mechanism of A. philoxeroides and provide theoretical foundation and advice for the management of A. philoxeroides.A greenhouse experiment was conducted to study the effects of nutrient level and N:P ratio on growth of A. philoxeroides and competition between A. philoxeroides and two non-invasive plants. In the experiment, A. philoxeroides was grown in monoculture or in mixture with native plant Oenanthe javanica and non-invasive alien plant Iris pseudacorus at three N:P ratios (1,10and100) combined with three levels of total nutrient availability (low, medium, high).The experiment that A. philoxeroides was grown in monoculture indicated that both nutrient level and N:P ratio had significant effects on the biomass accumulation, morphological characteristics, photosynthetic fluorescence, leaf nitrogen and phosphorus concentration of A. philoxeroides. High nutrient level significantly increased the biomass accumulation, branch number, tiller number and the stolon length of A. philoxeroides. N:P ratio had significant influence on the aboveground part of A. philoxeroides, such as branch number, tiller number, length of maximum node and the stolon length, but had no significant effect on the biomass allocation. The SLA (Specific leaf area) of A. philoxeroides decreased significantly with the nutrient availability increasing, having lowest SLA under high nutrient level, and meanwhile under the same nutrient level, the SLA of A. philoxeroides increases with the N:P ratio decreasing, having highest SLA under N:P ratio1.The experiment that A. philoxeroides was grown in mixture with O.javanica and I. pseudacorus showed that A. philoxeroides had higher plasticity than other two non-invasive species, having higher adaptability to the different nutrient conditions. Invasive species A. philoxeroides had stronger response to the change of nutrient level and N:P ratio than other two species, promoting its the growth and competitive ability. And the SLA of A. philoxeroides had higher plasticity than that of O. javanica under different nutrient conditions. Higher leaf nitrogen and phosphorus concentration of A. philoxeroides indicated that species A. philoxeroides had higher ability to require nutrient, promoting its growth and invasion.When grown in mixture with two studied non-invasive plants, A. philoxeroides had absolute competitive advantage. High nutrient level could increase the competitive advantage of A. philoxeroides and low nutrient level could to some extent decrease its invasion. The effect of N:P ratio on the competitive advantage of A. philoxeroides changed with the nutrient level. Under medium nutrient level, phosphorus played an important role in the invasion of A. philoxeroides, while under low and high nutrient level, phosphorus had no effect on the competitive advantage of A. philoxeroides.In conclusion, both nutrient level and N:P ratio had significant effects on growth of A. philoxeroides and on the competition relationship between A. philoxeroides and two non-invasive plants. A. philoxeroides has more phenotypic plasticity than the other two non-invasive plants and adapts to high nutrient environment. These results would be of great importance for revealing the invasive mechanism of A. philoxeroides and predicting the effect of environment changing on its invasion. Meanwhile, the results could provide theoretical foundation for the scientific management of A. philoxeroides.更多还原