不同光照强度下物种组合对沉水植物苦草种间关系的影响

为了解种间关系对沉水植物群落结构的影响，在不同光照(20%自然光和50%自然光)和不同物种组合下，研究了长江中下游常见优势沉水植物苦草(Vallisneria natans)与黑藻(Hydrilla verticillata)和穗状狐尾藻(Myriophyllum spicatum)的相互作用。结果表明，在低光下，苦草与穗状狐尾藻混种时，苦草生物量、株高和叶数均没有明显变化，当穗状狐尾藻的比例较高时，苦草根长生长受到抑制，根叶比呈下降趋势；在高光下，穗状狐尾藻比例的增加会促进苦草单株生物量和叶生物量的增加，而对苦草株高、根长和叶数无显著影响；与黑藻混种相比，苦草与穗状狐尾藻混种时，苦草的株高、根长和叶数均无显著差异，而苦草的单株生物量和叶生物量均呈降低趋势。因此，物种组合和混种比例均会影响苦草与其他物种的相互作用关系，进而影响沉水植被的群落动态。

Effects of Species Composition on Interspecies Relationships of Submerged Plant Vallisneria natans Under Different Light Intensities

To understand the influence of interspecific relationships on community structure of submerged plants, the interaction of Vallisneria natans with Hydrilla verticillata and Myriophyllum spicatum was studied in the middle and lower reaches of the Yangtze River with different combinations of species under different light levels (20% and 50% nature light). The results showed that the biomass, height and leaf number of V. natans co-cultured with M. spicatum had not significant changes under low light intensity. The biomass of root and root/leaf of V. natans decreased with co-cultured ratio of M. spicatum increasing. Under high light intensity, the biomass and leaf biomass of V. natans increased with co-cultured ratio of M. spicatum increasing, while the height, root length and leaf number of V. natans had not change. There were no significant differences in height, root length and leaf number of V. natans between co-cultured with H. verticillate and M. spicatum, while biomass and leaf biomass of V. natans co-cultured with M. spicatum were lower than those co-cultured with H. verticillate. Therefore, both the species composition and co-cultured ratio could affect the interaction relationships between V. natans and other species, and then affect the community dynamics of submerged vegetation.