Environmental, biomass and biotic interactions data of Spartina sp. niches in the Bay of Arcahon

questions: invasiveness depends in part on the ability of exotic species to either exclude native dominants or to fill an empty niche. comparisons of niches and effects of closely related native and invasive species enable the investigation of this topic. does spartina anglica invade european salt marshes through competitive exclusion of the native spartina maritima or due to the occurrence of an empty ecological niche in highly anoxic conditions?location: the arcachon bay (france).methods: at three intertidal levels, we quantified competitive response and effect abilities of the two species through a cross-transplantation removal experiment. we also compared at three intertidal levels the biomass, root/shoot ratio, productivity and environmental conditions (elevation, salinity, potential redox and soil moisture) of salt marsh communities dominated by the exotic spartina anglica or the native spartina maritima.results: both established species showed similar biotic resistance to the invasion of the other species, but the exotic showed important intraspecific facilitation for growth. species had similar niches and total biomass along a gradient of anoxic conditions, but the exotic had a much higher root/shoot ratio and productivity than the native. owing to its rhizome density, the exotic showed a high ability to increase sediment oxygenation, likely to explain its important intraspecific facilitation.conclusions: our results showed that the invasion success of s. anglica cannot be explained by the competitive exclusion of the native or by its ability to fill an empty niche along a gradient of anoxia. its behaviour as a self-facilitator invasive engineer is very likely to explain its rapid spread in the bay and biotic resistance to the colonization of other congeneric species when established in dense patches. additionally, we suggest that physical disturbance in the marsh communities dominated by the native s. maritima may disrupt its biotic resistance against the invasion of s. anglica.

探究入侵物种的侵扰性部分取决于其排除本地优势物种或填补空缺生态位的能力。通过对比密切相关本地及入侵物种的生态位和影响，本研究旨在深入探讨该议题。斯帕蒂纳·安格利卡是否通过竞争性排除本地斯帕蒂纳·马里蒂玛，或是在高度缺氧条件下出现的空生态位而入侵欧洲盐沼？研究地点位于法国的阿卡雄湾。研究方法包括在三个潮间带层次上，通过交叉移植去除实验量化两种物种的竞争响应和效应能力。同时，在三个潮间带层次上比较了由外来斯帕蒂纳·安格利卡或本地斯帕蒂纳·马里蒂玛占主导的盐沼社区的生物量、根/茎比、生产力和环境条件（海拔、盐度、潜在氧化还原和土壤湿度）。结果显示，两种已建立物种对其他物种的入侵表现出了相似的生物阻力，但外来物种在生长方面显示出重要的种内促进作用。物种在缺氧条件梯度上具有相似的生态位和总生物量，但外来物种的根/茎比和生产率显著高于本地物种。由于其根茎密度大，外来物种表现出提高沉积物氧化的高能力，这可能是其种内促进作用重要的原因。结论：我们的结果表明，斯帕蒂纳·安格利卡的入侵成功不能仅用本地物种的竞争排除或其沿缺氧条件梯度填补空缺生态位的能力来解释。其作为自我促进的入侵工程师的行为很可能解释了其在湾区的快速扩散以及在其密集斑块中建立后对其他同种物种的殖民抗性。此外，我们建议，在本地斯帕蒂纳·马里蒂玛占主导的沼泽社区中的物理干扰可能会破坏其对抗斯帕蒂纳·安格利卡入侵的生物阻力。