Studies across the United States and globally have revealed that mature riparian trees often utilize little streamwater, relying on soil moisture and groundwater instead. Contrastingly, riparian plants growing in wetland systems in the southeastern US use greater proportions of swamp water. The purpose of the present study was to determine if plant water uptake was linked to surface flow regime of the riparian system, characterized by stream flow and standing pond water nearby. Water sources of Liquidambar styraciflua growing along Whetstone Creek, a perennial stream in Stoneville, NC, were determined and compared to those of individuals growing along adjacent spring-fed ponds by analyzing stable isotopic compositions of plant water. Plant water status and environmental variables were also monitored due to possible influences on the specific water sources accessed. It was expected that pondside individuals, due to the lower flow rate and increased pond water availability, would utilize a greater amount of surface water than groundwater, which is shallow at the site, compared to streamside trees. However, trees at both sites appeared to rely about equally on shallow soil and surface water, while groundwater contributed only a minor proportion to trees at both sites. There were no meaningful relationships between the water sources measured and environmental factors, and plant water status was consistently high for trees at both sites. The current study is one of the first to demonstrate quantitatively a strong reliance on surface water by mature riparian trees in the southeastern US.

美国和全球范围内的研究表明，成熟的河岸树木通常很少利用溪流水，而是依靠土壤水分和地下水。相反，在美国东南部的湿地系统中生长的河岸植物使用的沼泽水比例更高。本研究的目的是确定植物的摄水量是否与河岸系统的地表水流态有关，其特征是附近的溪流和立塘水。香蒲的水源通过分析植物水的稳定同位素组成，确定了在北卡罗来纳州斯通维尔的多年生小溪Whetstone Creek上生长的水，并将其与在相邻的春季养鱼池中生长的个体的水进行了比较。由于可能会对所使用的特定水源产生影响，因此还监控了工厂用水状态和环境变量。可以预料，由于水流流速较低和池塘可用水量增加，池塘旁的人比地面流的树木要利用比地面浅的地下水更多的地表水。但是，这两个地点的树木似乎都同样依赖浅层土壤和地表水，而地下水在这两个地点的树木中只占很小的比例。所测量的水源与环境因素之间没有有意义的关系，并且两个地点的树木的植物水分状况始终很高。当前的研究是第一个定量证明美国东南部成熟的河岸树木对地表水的强烈依赖的研究。