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首页> 外文期刊>Estuarine Coastal and Shelf Science >Hydrological modification, saltwater intrusion, and tree water use of a Pterocarpus officinalis swamp in Puerto Rico
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Hydrological modification, saltwater intrusion, and tree water use of a Pterocarpus officinalis swamp in Puerto Rico

机译：波多黎各紫檀（Pterocarpus officinalis）沼泽的水文改良，咸水入侵和树木用水

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Tidal freshwater forested wetlands occupy a narrow ecological space determined by the balance between saltwater and freshwater inputs to the system. However, this balance is not well understood. In the Caribbean, tidal freshwater-forested wetlands dominated by Pterocarpus officinalis are vulnerable to . changes in tidal influence and freshwater inputs. In this setting, the seasonal interactions of saltwater and freshwater inputs create less than ideal conditions for these forests to survive. Hence, it is crucial to have a better understanding of the hydrologic context of these and other tidal freshwater forested wetlands. We examined the extent of tidal forcing and saltwater influence in the largest Pterocarpus swamp of Puerto Rico by installing automated water level and conductivity recorders across a tidal creek transect at four different distances from the ocean, and by using water stable isotopes ratios (δD, δ~(18)O) as natural tracers to determine the most important freshwater sources for tree transpiration. Records of water level and salinity revealed that the amount of rainfall was most influential on saltwater wedge migration in the creek for locations at the front and back of the tidal network, but that tidal dynamics were most influential at the middle section of the tidal network. Saltwater intrusion into the deepest parts of the tidal network was most prominent during sustained dry periods. Isotopic ratios of the surface water samples in the forest revealed that most of the water there was derived from freshwater runoff, but there was a seasonal change in its relative contribution to the forest hydrology. During the dry season, high δ values suggested the presence of runoff-derived water that had undergone evaporation, and saline influences were found in locations where past deforestation created preferential pathways for this water. During both seasons, δ~(18)O values of groundwater revealed the influence of saline water at depths 60 cm and greater near the adjacent tidal creek. Nonetheless, ~(18)O-enriched stem water and low d-excess values suggested that Pterocarpus officinalis relies primarily on water accessed from unsaturated soil mounds that surround the tree and that are subject to evaporation, as opposed to groundwater at depth. This observation provides further insight to the adaptation mechanisms of Pterocarpus officinalis to survive in flooded ecosystems. In summary, our work demonstrates that for preventing saltwater intrusion, the amount of rainfall and freshwater inflow is more important than the sea level or the existence of an overland hydrological connection to the ocean.
机译：潮汐淡水森​​林湿地占据了狭窄的生态空间，这取决于盐水和淡水输入系统之间的平衡。但是，这种平衡尚不清楚。在加勒比地区，以紫檀为主的潮汐淡水森​​林湿地很容易受到侵害。潮汐影响和淡水输入量的变化。在这种情况下，盐水和淡水输入的季节性相互作用为这些森林的生存创造了不理想的条件。因此，至关重要的是要更好地了解这些和其他潮汐淡水森​​林湿地的水文背景。我们通过在距海洋四个不同距离的潮汐小溪横断面上安装自动水位和电导率记录仪，并使用水稳定同位素比（δD，δ），研究了波多黎各最大的紫檀沼泽中的潮汐强迫和盐水影响的程度。 〜（18）O）作为自然示踪剂，以确定树木蒸腾最重要的淡水源。水位和盐度的记录表明，降雨量对潮汐网前后两岸的小溪中的咸水楔迁移影响最大，但潮汐动力学在潮汐网的中部影响最大。在持续干旱期间，盐水侵入潮汐网络最深处的现象最为明显。森林中地表水样品的同位素比值表明，那里的大部分水来自淡水径流，但是其对森林水文学的相对贡献存在季节性变化。在干旱季节，较高的δ值表明存在径流水，这些水已经蒸发，并且在过去的森林砍伐为该水创造了优先途径的位置发现了盐分的影响。在两个季节中，地下水的δ〜（18）O值都显示了邻近潮汐小溪附近60厘米及更大深度的盐水的影响。尽管如此，〜（18）O富集的干水和较低的d-过量值表明，紫檀主要依靠从围绕树的非饱和土丘获取的水，这些丘丘易于蒸发，而不是深层地下水。该观察结果进一步揭示了紫檀在水淹的生态系统中生存的适应机制。总而言之，我们的工作表明，为了防止盐水入侵，降雨和淡水的流入量比海平面或与海洋的陆上水文联系更为重要。

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