豚草入侵对新疆伊犁河谷林下本地草本植物群落结构的影响

为探究外来入侵植物豚草（Ambrosia artemisiifolia）对本地植物群落结构的影响，结合区内林下草本植物调查和室内分析方法，分析了豚草不同入侵压力下（无入侵、轻度入侵、中度入侵、重度入侵）本地草本植物丰富度、盖度等特征，探讨了地形、气候、土壤、光照、人口密度等外部因素与豚草种群特征、本地植物群落结构之间的关系。结果表明：豚草种群盖度与其高度、密度、生物量显著正相关。与对照相比，轻度入侵下本土草本植物Shannon-Wiener多样性指数和Pielou均匀度指数显著增加，丰富度、盖度未出现显著差异。随着豚草入侵程度加剧，本地草本植物物种丰富度、盖度极显著降低，样方Shannon-Wiener多样性指数先升高再降低，本土草本植物Pielou均匀度指数差异不显著。冗余分析（RDA）表明，土壤全氮、与道路距离、土壤全磷、郁闭度对研究区植物群落结构影响最大，土壤全氮含量随豚草盖度和生物量增加而减少，距道路越近或光照越强，豚草盖度和生物量越高。增强伊犁河谷地区交通往来货物豚草检验检疫力度、增加林内植被郁闭度或是抑制区内豚草入侵的有效手段。

Effect of invaded Ambrosia artemisiifolia on understory native plant community structure in Yili River Valley of Xinjiang

To explore the effects of invasive species on understory native plant community structure, individual abundance, coverage of native plant species were investigated under different invasion pressures (no invasion, low invasion, medium invasion, and high invasion) of invasive species Ambrosia artemisiifolia with field investigation and analysis. The relationship between the external factors such as topography, climate, soil, light, and population density and the population characteristics of A. artemisiifolia and the local plant community structure was discussed. The results showed that A. artemisiifolia coverage was positively correlated with invasion height, invasion density, and aboveground biomass. Compared with the control no contain A. artemisiifolia, under the low invasion pressure, Shannon-Wiener diversity index and Pielou evenness index of native plant were significantly increased, while there were no significant change of native species richness and coverage. With increase in invasion cover, native species richness and coverage were decreased gradually, the native plant Shannon-Wiener diversity index showed a downward tendency after initially rising, and no significant differences in Pielou evenness index of native plant. Redundancy Analysis (RDA) analysis showed that soil total nitrogen, distance to the road, soil total phosphorus, and canopy density were the main factors influencing relationships between the success of invasive plants and native plant diversity. The soil total nitrogen content decreased with increase of A. artemisiifolia coverage and biomass. The closer to the road or at higher light intensity, the higher coverage and biomass of A. artemisiifolia. While intensify inspection of invasive species in traffic flow and increasing canopy density could inhibit A. artemisiifolia spread.