乡土植物芦苇对外来入侵植物加拿大一枝黄花的抑制作用

在城市建筑荒地中设立实验样地，通过对样方植物进行实地观测，并结合实验室比叶重和生物量测算，了解和分析野外建筑荒地中自然混生条件下芦苇(Phragmites communis)和加拿大一枝黄花(Solidago canadensis)的竞争过程和结果。结果表明芦苇和加拿大一枝黄花混生群落中芦苇发展近似于单优群落，芦苇以较高的平均株高和密度抑制加拿大一枝黄花生长，混生群落逐渐趋向于芦苇单优群落。混生群落芦苇比叶重和平均每株生物量近似于单优群落，加拿大一枝黄花比叶重和平均每株生物量显著低于其单优群落，光合作用受到显著抑制。de Wit模型分析显示，混生群落中芦苇和加拿大一枝黄花相互竞争、拮抗，前者竞争攻击力高于后者，模型预测混生群落中芦苇最终将把加拿大一枝黄花从样地中排除出去。浸提液种子培养显示加拿大一枝黄花具有化感作用，在低浓度条件(12.5mg/mL)下，对自生种子发芽有促进作用，高浓度条件下出现强烈抑制，但各浓度下芦苇种子不受加拿大一枝黄花化感作用影响；芦苇种子繁殖能力相对较弱，混生样地中加拿大一枝黄花在芦苇竞争胁迫下，种子千粒重和发芽率显著上升，扩散能力增强。芦苇具有在一定区域生态控制加拿大一枝黄花的潜力。

Inhibition of local plant Phragmites communis on the invasive plant Solidago canadensis

This article discusses the possibility and mechanism of utilizing a local plant species, Pharammites communis, to control an invasive species Solidago Canadensis. We monitored specific ecological parameters of the two species in a complete growing season and also measured respectively the specific leaf weight and biomass. To calculate the competitiveness and the aggressiveness between the two species, the de Wit model was applied so as to predict the community succession pattern. We examined the reproduction strategy of the two species based on the comparison of the thousand-seed-weight and seed germination percentage. A seed culture with the tissue extraction of the two plants was conducted to observe the reciprocal allelopathic effect. In these experiments, we collected samples from a set of quadrates established in the construction wastelands in Minhang District located in southwest Shanghai. The experiment has suggested the following major findings. First, in the species mixed communities and at the end of the growing season, the average height, the coverage degree, the density and the important value of the P. communis, which approximated to the results obtained in P. communis mono-community, were all superior to those of S. canadensis. Second, there was no significant difference of the specific leaf weight and biomass per capita of P. communis between the species mixed communities and the P. communis mono-communities, while the two index of S. canadensis in the species mixed communities were significantly lower than those in the S. canadensis mono-communities. Third, the de Wit model showed the existence of competition and antagonism between P. communis and S.canadensis in the species mixed communities, and a significant inferiority of S. canadensis in aggressiveness compared to P. communis. The model also implied that P. communis would expel S. canadensis out of the quadrates as their competition progressed. Fourth, the thousand-seed-weight of P. communis was relatively higher than that of S. canadensis in their respective mono-communities, while the germination percentage was lower, which suggested an inferior distribution and reproduction capability of P. communis. And in the species mixed communities, the two data of the two species were significantly higher compared to those in their mono-communities, with a more noteworthy change of S. canadensis, which suggested that it enhanced its distribution and invasive capability more than P. communis does. Finally, S. canadensis extraction exerted an allelopathic effect on itself but imposed no effect on P. communis. Compared to the control group, the germination percentage of S. canadensis was higher at a low S. canadensis extraction concentration (12.5mg/mL), but it was lower at a higher S. canadensis extraction concentration. On the contrary, S. canadensis extraction of various concentrations exhibited no conspicuous allelopathic effect on P. communis. Based on the observations and results, we conclude that the local plant P. communis has the potential to control and prevent the expansion of the alien invasive plant S. canadensis in our study areas.