1. Halophyte distributions on saltmarshes are strongly related to elevation in the tidal frame. However, collinearity between elevation, the consequent inundation regime, and sediment waterlogging/redox potential obscures the proximate causes of distribution patterns. We sought to distinguish the effects of elevation per se from those of waterlogging by manipulating microtopography.
2. We experimentally manipulated elevation by ±15 cm at locations that spanned the elevation ranges of three saltmarshes recently reactivated by managed coastal realignment. Experimental plots were initially cleared of any vegetation. Elevation and sediment redox potential were determined for each plot. We planted five perennial species (Armeria maritima, Atriplex portulacoides, Limonium vulgare, Plantago maritima and Triglochin maritima) in half of the plots, recording survival over 4 years, and monitored natural colonization of the other plots.
3. Overall, redox potential increased with elevation. Sediments were more oxidizing in raised plots and more reducing in lowered plots. Redox reductions in lowered plots were in line with those that would be predicted from the overall redox/elevation relationship, but increases in raised plots were greater than predicted from elevation alone.
4. Plant colonization and survival was poorer in lowered plots and, for most species, improved in raised plots. This poorer colonization and survival can, in part, be attributed to the concomitant alterations in redox potential and elevation in the tidal frame, but microtopographic manipulation also had substantial independent effects on plant performance, including on the survival of all planted species and the colonization of Puccinellia maritima, Salicornia europaea agg. and Tripolium pannonicum.
5. Synthesis. Microtopography can have effects on sediment chemistry and plant performance similar in magnitude to those of overall tidal elevation. Understanding how its effects modulate the relationship between tidal elevation, redox and other environmental conditions helps clarify the abiotic factors that fundamentally determine halophyte colonization and survival. These results support the use of topographic manipulation to enhance the diversity of created saltmarshes.

中文翻译：

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操纵盐沼微地形可调节海拔高度对沉积物氧化还原电位和盐生植物分布的影响

1. 盐沼上的盐生植物分布与潮汐架中的海拔高度密切相关。但是，高程，随之而来的淹没状态和沉积物内涝/氧化还原电位之间的共线性掩盖了分布模式的近因。我们试图通过操纵微形貌来将高程本身的影响与内涝的影响区分开。
2. 我们在经过管理的沿海调整最近重新激活的三个盐沼的海拔范围内，通过实验将海拔高度提高了±15厘米。最初清除了实验地的任何植被。确定每个样区的高程和沉积物氧化还原电位。我们在一半的地块中种植了五个多年生物种（海地大虾，滨藜，，草，车前草和海螯虾），记录了4年的生存情况，并监测了其他地块的自然定居情况。
3. 总体而言，氧化还原电位随海拔升高而增加。高地块中的沉积物氧化程度更高，低地块中的沉积物减少量更多。降低的地块中的氧化还原减少量与根据整体氧化还原/海拔关系所预测的减少量一致，但升高的地块的增加量大于仅根据海拔高度所预测的增加量。
4. 低地块的植物定植和存活较差，对大多数物种而言，高地块的植物定植和存活率提高。这种较差的定殖和生存能力部分可以归因于氧化还原电位和潮汐架抬高的同时变化，但显微地形学操作也对植物的生长性能，包括对所有种植物种的生存和定殖的影响，具有实质性的独立影响。桔梗，欧洲刺槐。和Tripolium pannonicum。
5. 合成。微观地形对沉积物化学和植物性能的影响与总体潮汐高度的影响相似。了解其作用如何调节潮汐升高，氧化还原和其他环境条件之间的关系有助于阐明从根本上决定盐生植物定居和生存的非生物因素。这些结果支持使用地形操纵来增强盐沼的多样性。