Li Hong-Li, Wang Yong-Yang, An Shu-Qing, Zhi Ying-Biao, Lei Guang-Chun, Zhang Ming-Xiang
School of Nature Conservation, Beijing Forestry University, Beijing 100083, China.
The State Key Laboratory of Pollution Control and Resource Reuse, School of Life Science, Nanjing University, Nanjing 210093, China.
Sci Rep. 2014 Oct 23;4:6748. doi: 10.1038/srep06748.
Different types of sediments in salt marsh have different physical and chemical characters. Thus sediment type plays a role in plant competition and growth in salt marsh ecosystems. Spartina anglica populations have been increasingly confined to upper elevation gradients of clay, and the niche sediment has changed. Because the niches of S. anglica and the native species Scirpus triqueter overlap, we conducted a greenhouse experiment to test the hypothesis that plant competition has changed under different types of sediments. Biomass and asexual reproduction were analyzed, and inter- and intraspecific competition was measured by log response ratio for the two species in both monoculture and combination under three sediment types (sand, clay and mixture of sand and clay). For S. anglica, biomass, ramet number and rhizome length in combination declined significantly compared with those in monoculture, and the intensity of interspecific competition was significantly higher than that of intraspecific competition under all sediments. For S. triqueter, the intensities of intra- and interspecific competition were not significantly different. This indicates that S. triqueter exerts an asymmetric competitive advantage over S. anglica across all sediments, but especially clay. Thus the sediment type changes competition between S. anglica and S. triqueter.
盐沼中不同类型的沉积物具有不同的物理和化学特性。因此，沉积物类型在盐沼生态系统中的植物竞争和生长中发挥着作用。大米草种群越来越多地局限于黏土的高海拔梯度区域，其适宜的沉积物生态位发生了变化。由于大米草和本地物种藨草的生态位重叠，我们进行了一项温室实验，以检验在不同类型沉积物下植物竞争是否发生变化的假设。分析了生物量和无性繁殖情况，并通过对数响应比来衡量两种物种在单一培养和混合培养下，在三种沉积物类型（沙子、黏土以及沙子和黏土的混合物）中的种间和种内竞争。对于大米草来说，混合培养中的生物量、分株数和根茎长度与单一培养相比显著下降，并且在所有沉积物类型下，种间竞争强度均显著高于种内竞争强度。对于藨草而言，种内和种间竞争强度没有显著差异。这表明，在所有沉积物类型中，尤其是黏土中，藨草对大米草具有不对称的竞争优势。因此，沉积物类型改变了大米草和藨草之间的竞争关系。
