植物生态学报 ›› 2004, Vol. 28 ›› Issue (6): 787-793.doi: 10.17521/cjpe.2004.0103

• 论文 • 上一篇    下一篇

外来入侵植物北美车前繁殖及光合生理生态学研究

郭水良1,2 方芳1 黄华1 强胜3   

  1. (1 浙江师范大学化学与生命科学学院,浙江金华321004)
  • 出版日期:2004-11-10 发布日期:2004-11-10

STUDIES ON THE REPRODUCTION AND PHOTOSYNTHETIC ECOPHYSIOLOGY OF THE EXOTIC INVASIVE PLANT, PLANTAGO VIRGINICA

GUO Shui-Liang1,2 FANG Fang1 HUANG Hua1 and QIANG Sheng3   

  1. (1 College of Chemistry and Life Sciences, Zhejiang Normal University, Jinhua, Zhejiang 321004, China)
  • Online:2004-11-10 Published:2004-11-10

摘要: 北美车前(Plantago virginica)原产北美,20世纪50年代进入我国华东地区,近年来其种群呈现爆发式增长态势,已分布到上海、浙江、江西、江苏等省区,是一种典型的生态入侵种。本文计测了该种在不同密度下的繁殖指标,统计了种群密度与繁殖指标间的关系;应用LAC-4 (ADC英国)光合和蒸腾系统测定了该种及其伴生杂草一年蓬(Erigeron annuus)、小飞蓬(Conyza canadensis)、野塘蒿(Conyza bonarinsis)、马缨丹(Lantana camara)、空心莲子草(Alternathera philoxeroides)、菊芋(Helianthus tuberoses)、蓖麻(Ricinus communis)、紫茉莉(Mirabilis jalapa)、车前(Plantago asiatica)、苦苣菜(Sonchus oleraceus)、羊蹄(Rumex japonicus)、藜(Chenopedium album)和黄鹌菜(Youngia japonica)等杂草的光合作用指标,作出了它们的光合光响应曲线。主要实验结果有:1)北美车前个体花穗重(Y1)、花数/穗(Y2)与种群密度(X)呈现倒数关系(Y1 = 0.138 2+15.959 8/X, Y2 = 46.306 9+6 914.07/X);随着种群密度增加,北美车前的繁殖投资(Y3)、与繁殖投资关系密切的种子数/营养器官重(Y4)呈线性增加(Y3 = 0.046 9+0.000 2X,Y4 = 130.24+0.023 9 X); 2) 随着北美车前种群密度的增加,个体间的大小不整齐性(Y5)变小(Y5 = 0.374 8 - 0.000 02X); 3)种群个体间大小不整齐性(Y5)与繁殖投资(X)呈明显负相关(Y5 = 0.379 3 - 0.106 6 X),即随着个体大小不整齐性的增加,北美车前种群的繁殖投资减少;4)以自然条件下测得的光合作用数据为基础,拟合得到了北美车前及其它13种伴生杂草的光合光响应曲线。北美车前的光合光响应曲线符合Y= - 7E-06X2+0.022 3X-0.831 2,光补偿点、光饱和点和最大净光合速率分别为37.32 μmol·m-2·s-1、159 3 μmol·m-2·s-1和16.93 μmol CO2·m-2·s-1,说明北美车前是典型的阳生杂草。从光补偿点分析,北美车前的耐荫能力比车前、黄鹌菜、小飞蓬、一年蓬、野塘蒿、蓖麻、加拿大一枝黄花(Solidago canadensis)、苦苣菜、羊蹄和马缨丹的要弱;北美车前净光合速率比一年蓬、小飞蓬、野塘蒿和加拿大一枝黄花等要低些,但是比藜、苦苣菜、蓖麻等的要高,与同属的车前比较接近;5)在5月下旬,杂草性极强的一年蓬、小飞蓬和空心莲子草的光合午休现象不明显,逸生杂草紫茉莉具有明显的光午休现象,北美车前是早春杂草,在5月下旬也有明显的光合午休现象,反映出该种不能够很好地适生于5月下旬的高温强光环境。通过分析,得出如下结论:1)随着种群密度的增加,北美车前产生种群自疏作用,使个体大小不整齐性下降;高密度给北美车前种群造成某种逆境状态,种群以r-对策的生存方式适应环境,提高其繁殖投资,产生尽可能多的种子,以保证后代的生存,这反映出北美车前在繁殖策略上灵活的调节能力;2)北美车前种群在定居后,如果定居点不再受到人为干扰,其种群将被快速更替,这与其粘液性的种子、较高的光补偿点有关;3)通过保护植被,定植高秆植物,减少对环境的干扰,能够有效地治理该外来杂草。

Abstract:
Plantago virginica, an annual weed species originating from North America, was introduced into Eastern China during the 1950's. The populations of this invasive species have spread rapidly during recent years in Zhejiang, Jiangsu, Jiangxi, Guangdong and Hunan provinces. In the present paper, reproductive indices of Plantago virginica, including spike weight per individual, flower number per spike, reproductive biomass per vegetative biomass and Gini coefficient, which indicates individual size inequality, were obtained from populations growing at different densities. The photosynthetic indices of Plantago virginica and its companion species were determined using a LCA-4 portable photosynthesis and transpiration system (ADC, England). The companion species included Erigeron annuus, Conyza canadensis, Conyza bonarinsis, Lantana camara, Mirabilis jalapa, Alternathera philoxeroides, Ricinus communis, Chenopodium album, Rumex japonicus, Plantago asiatica, Sonchus oleraceus and Helianthus tuberoses. Their net photosynthetic rates (Y) and leaf photosynthetic active radiation (X) were modeled using the equation Y=aX2+bX+c. The main experimental results are summarized below. 1) During the reproductive phase, the relationships of the population density (X) with spike weight per individual (Y1), flower number (Y2), reproductive effort (Y3) and seed numbers per vegetative biomass (Y4) were as follows: Y1 = 0.138 2+15.959 8/X, Y2 = 46.306 9+6 914.07/X, Y3 = 0.046 9 + 0.000 2X and Y4 = 130.24 + 0.023 9X. 2) With an increase in the population density of P. virginica, the individual size inequality (Gini coefficient, Y5) declined by the following relationship: Y5 = 0.374 8 - 0.000 02X. 3) The individual size inequality (Y5) was negatively related to reproductive effort (X), following Y5 = 0.379 3 - 0.106 6X, which indicated that the population reproductive effort declined with an increase in individual size inequality. 4) The photosynthesis (Y) - light (X) response curve followed: Y = -7E-06X2+0.022 3X-0.831 2. The light compensation point, light saturation point and the maximum net photosynthetic rate of P. virginica were 37.32 μmol·m-2·s-1, 1 593 μmol·m-2·s-1 and 16.93 μmol CO2·m-2·s-1, respectively, indicating that P. virginica is a typical heliophyte. The shade-tolerant ability of P. virgincia was lower than that of Plantago asiatica, Youngia japonica, Conyza canadensis, Erigeron annuus, Conyza bonarinsis, Ricinus communis, Solidago canadensis, Sonchus oleraceus, Rumex japonicus and Lantana camara, its net photosynthetic rate was lower than that of Erigeron annuus, Conyza canadensis, Conyza bonarinsis and Solidago canadensis, but higher than that of Chenopodium album, Sonchus oleraceus, Ricinus communis and similar to that of Plantago asiatica. 5) During the last ten-day period of May, the photosynthetic “midday-depression” was not apparent in the three typical weedy species (Erigeron annuus, Conyza canadensis and Alternathera philoxeroides) but obvious in P. virginica and the escaped species, Mirabilis jalapa. Plantago virginica is an early-spring weedy species, and the high temperature and intensive light were not suitable for its growth during the last ten-day period of May. We drew the following conclusions based on the experimental results. 1) The high population density of P. virginica resulted in self-thinning, which reduced the individual size inequality. Because of environmental stress resulting from high densities, the high-density population of P. virginica switched to an r-strategy to increase its reproductive output by producing more seeds in order to maintain large numbers of offspring. Obviously, Plantago virgincia had the flexibility to adapt its reproductive strategy to environmental conditions. 2) If there was no human disturbance to the recipient environments, the populations of P. virginica would rapidly decline in the community over five successive years due to their higher light compensation point and their mucilage seeds. 3) Our suggestions for controlling Plantago virginica include protection of vegetation, planting horticultural plants with higher stalks and reducing disturbance to the recipient environments.