黄顶菊对入侵地群落动态及植物生长生理特征的影响

为明确黄顶菊对入侵地植物群落和土著植物生理生长的影响机制,采用同质园试验对入侵和非入侵土壤的植物群落开展了整个生育期动态监测,并分析了黄顶菊入侵对狗尾草、羽叶鬼针草、灰绿藜、地肤4种土著植物生长和生理特征的影响规律。结果表明:黄顶菊入侵土壤植物群落多样性指数低于非入侵地,且有季节性差异,随生育期的推进差异逐渐减小;黄顶菊对本地植物的生长指标有显著影响(P0.05),随时间变化显著,但存在物种差异;4种植物的净光合速率(Pn)、气孔导度(Cd)、蒸腾速率(Tr)在非入侵土壤生长显著高于入侵地土壤(P0.05);而4种植物在入侵土壤生长的比叶面积(SLA)、比根长(SRL)、比根面积(SRA)显著高于本地土壤(P0.05)。综上,黄顶菊入侵抑制了本地植物的光合效率,减少了生物量的积累,导致本地植物群落的生物多样性水平降低,但表现出季节差异;不同物种对黄顶菊入侵胁迫的响应表现种间特异性,为理解入侵种对群落结构影响和实现入侵生境恢复提供了理论依据。

Effects of Flaveria bidentis invasion on the community composition and performance of native plants grown in invaded soil

To clarify the mechanism underlying the effects of invasive plant, Flaveria bidentis, on the community and physiological growth of indigenous plants, a common garden experiment was conducted. To monitor the dynamic growth of plant communities in invaded and non-invaded soils, we further determined the growth and physiological variables of four indigenous plants-Setaria viridis, Bidens maximowicziana, Chenopodium glaucum, and Kochia scoparia. The results showed that the plant community diversity index of F. bidentis-invaded soil was less than that of non-invaded soil, but this difference gradually decreased with time. Flaveria bidentis had significant effect on the growth index of native plants (P < 0.05), but this effect was species-specific. The net photosynthetic rate, stomatal conductance, and transpiration rate of the four native species grown in native soil were significantly higher than those of plants grown in the invaded soil (P < 0.05), signifying the suppression effect of F. bidentis on native vegetation. However, the specific leaf area(SLA), specific root length(SRL), and specific root area(SRA) of the four native species grown in invaded soil were significantly higher than those of plants grown in native soil (P < 0.05), indicating species-specific tolerant strategies to competition from the invader. Overall, the invasion of F. bidentis inhibited the photosynthetic efficiency of native plants and reduced the accumulation of biomass, decreasing the biodiversity level of native plant communities, but it showed seasonal differences. The response of different species to the invasion of F. bidentis showed interspecific difference. The study provides a theoretical basis to understand the influence of invasive species on the native community structure with time and to restore invaded habitats.