Response of Coastal Plants to Salt Water Intrusion

佛罗里达州南部相对较浅的淡水地下水位位于多孔性的底质(橄榄石灰岩)中，特别容易受到海水入侵的影响。除了严重的影响外，人们对造成这种入侵的更微妙的影响和过程知之甚少。众所周知，抽取地下水以供应不断扩大的城市地区和修建运河是造成入侵问题的原因之一。然而，关于咸水入侵的几个问题仍有待回答。例如，是否有季节性的入侵；旱季和雨季？如果海平面上升是因为全球气候变化，那么这种影响是否已经在佛罗里达州南部的沿海植物群落中检测到？咸水入侵对植物群落的影响如何；这是否意味着外来有害植物的增加？这项拟议的研究解决了这些问题。这项研究的结果将回答许多关于植物如何对周期性和慢性盐分胁迫做出反应的基本科学问题。这项研究将在很大程度上依赖于植物生物量的稳定同位素分析。最近，通过这项技术，人们对生物系统有了很多了解。稳定同位素分析将有助于揭示植物群落咸水入侵的历史。此外，稳定同位素技术可用于将水文学和生态生理学概念结合起来研究咸水入侵。这项研究的潜在应用是相当清楚的。佛罗里达州南部的海水入侵很大程度上是由水管理项目造成的。这项研究有助于更准确地预测水管理战略的效果。例如，如果海水入侵是季节性的，那么一个适当的战略将是在旱季限制淡水抽水。此外，这里将要使用的实验技术将允许在不可逆转的变化发生之前检测到植物群落中的咸水入侵。

Southern Florida's relatively shallow freshwater table in a porous substrate, (oolitic limestone), is particularly susceptible to ocean water intrusion. Other than gross effects, little is known about more subtle effects and processes responsible for this intrusion. It is well known that pumping of ground water to supply expanding urban areas and canal building have contributed to intrusion problems. Several questions about salt water intrusion remain to be answered, however. For example, Is there a seasonality of intrusion; dry season versus wet season? If ocean levels are rising because of global climatic changes, is this effect already detectable in coastal plant communities of southern Florida? What about the effect of salt water intrusion in plant communities; will this mean an increase in exotic pest plants? The proposed research addresses such questions. The results of this research will answer many basic scientific questions about how plants react to periodic and chronic salt water stress. The research will rely heavily on stable isotope analysis of plant biomass. Recently much has been learned about biological systems with this technique. Stable isotope analysis will shed light on the history of salt water intrusion in plant communities. In addition, stable isotope techniques can be used to integrate hydrological and ecophysiological concepts in the study of salt water intrusion. The potential applications of this research are quite clear. Much of the salt water intrusion in southern Florida is caused by water management projects. This research can aid in predicting more precisely the effects of water management strategies. As an example; if ocean water intrusion is seasonal, then an appropriate strategy would be limitation of freshwater pumping during the dry season. Further, the experimental techniques to be used here will permit the detection of salt water intrusion in plant communities before irreversible changes occur.