Bertness Mark D, Wikler Karen, Chatkupt Tom
Program in Ecology and Evolutionary Biology, Brown University, 02912, Providence, RI, USA.
Oecologia. 1992 Aug;91(2):171-178. doi: 10.1007/BF00317780.
Tidal flooding is widely believed to be an important determinant of marsh plant distributions but has rarely been tested in the field. In New England the marsh elder Iva frutescens often dominates the terrestrial border of salt marshes and we examined its flood tolerance and distribution patterns. Marsh elders only occur at elevations where their roots are not subject to prolonged water table flooding. Consequently they are found on the terrestrial border of marshes and at lower elevations associated with drainage ditches and locally elevated surfaces. Marsh elders transplanted to elevations lower than they normally occur died within a year with or without neighbors and greenhouse tests revealed that I. frutescens is much less tolerant of flooded soil conditions than plants found at lower marsh elevations. We also manipulated the water table level of field plots and found that increasing or decreasing water table drainage led to enhanced and diminished I. frutescens performance, respectively. Our results demonstrate the importance of water table dynamics in generating spatial patterns in marsh plant communities and provide further evidence that supports the hypothesis that the seaward distributional limits of marsh plant populations are generally dictated by physical processes.
潮水淹没被广泛认为是沼泽植物分布的一个重要决定因素，但在实地很少得到验证。在新英格兰地区，沼泽接骨木（Iva frutescens）常常在盐沼的陆地边界占据主导地位，我们研究了它的耐淹能力和分布模式。沼泽接骨木仅出现在其根部不会长期被地下水位淹没的海拔高度。因此，它们生长在沼泽的陆地边界以及与排水沟和局部高地相关的较低海拔处。移植到比其正常生长海拔更低处的沼泽接骨木，无论有无相邻植株，都会在一年内死亡，并且温室试验表明，与生长在较低沼泽海拔处的植物相比，沼泽接骨木对淹水土壤条件的耐受性要低得多。我们还对田间地块的地下水位进行了调控，发现提高或降低地下水位排水分别会导致沼泽接骨木生长状况增强或减弱。我们的研究结果证明了地下水位动态在形成沼泽植物群落空间格局方面的重要性，并进一步提供了证据支持这一假说，即沼泽植物种群向海的分布界限通常由物理过程决定。
