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首页> 外文学位 >Relation of hydrogeology, soils and vegetation on the wetland-to-upland transition zone of the Great Dismal Swamp, Virginia and North Carolina.
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Relation of hydrogeology, soils and vegetation on the wetland-to-upland transition zone of the Great Dismal Swamp, Virginia and North Carolina.

机译：大沼泽沼泽，弗吉尼亚州和北卡罗来纳州从湿地到高地过渡带的水文地质，土壤和植被的关系。

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Data on hydrogeology, soils and vegetation collected on the wetland-to-upland transition zone of the Great Dismal Swamp were used to characterize this zone, to analyze changes along the moisture/elevation gradient, and to select tentative wetland-upland boundaries based on these three parameters. Recharge-discharge relationships on the transects, hydraulic connection of the Tabb aquifer underlying the swamp with aquifers in formations further west, evapotranspiration, and precipitation were responsible for high water tables and water-table fluctuations encountered on all transects during the growing season. Transition zone vegetation was dominated by three facultative hydrophytes, Acer rubrum, Liquidambar styraciflua, and Nyssa sylvatica. On the basis of DECORANA ordination performed on consecutive 25-m increments, the increments were divided into three types: wetland (subdominants primarily obligate hydrophytes, facultative wetland or facultative species occurring at the wetter end of the moisture/elevation gradient); transitional wetland (subdominants primarily a mixture of facultative wetland, facultative and facultative upland species); and upland (subdominants primarily facultative, facultative upland or upland species). Water was within the root zone (0-30 centimeters below the ground surface) an average of 50-100 percent of the growing season for well sites classified wetland, 25-100 percent for most well sites classified transitional wetland and {dollar}<{dollar}25 percent for well sites classified upland. Soils were classified as hydric along almost the entire length of transects A, B, and C; more than half of transect D had nonhydric soils. Except on transect B, wetland boundaries determined on the basis of each parameter were different, but fairly close considering the length of the transects and certain assumptions made during the analysis. Elevation of the individual wetland-upland boundaries decreases from north-to-south along the 48-kilometer transition zone except at transect B. A method developed to determine wetland boundaries based on the 3 parameters has 3 alternatives for delineating boundaries and should result in greater precision in placement.
机译：利用大雾沼泽湿地-高地过渡带上收集的水文地质，土壤和植被数据表征该带，分析沿湿度/海拔梯度的变化，并基于这些数据选择暂定的湿地-高地边界三个参数。横断面的补给关系，沼泽下方的Tabb含水层与西侧地层中的含水层的水力联系，蒸散和降水是生长季节所有横断面遇到的高地下水位和地下水位波动的原因。过渡带植被以三种兼性水生植物为主，即红槭，枫香，枫香和Nyssa sylvatica。根据连续25米增量进行的DECORANA排序，将增量分为三种类型：湿地（主要为专性水生植物，兼性湿地或兼性物种出现在湿度/海拔梯度的较湿端）；过渡湿地（主要是兼性湿地，兼性和兼性高地物种的混合物）；和高地（主要为兼性，兼性高地或高地物种）。在分类为湿地的井场中，水处于生根区（低于地面0-30厘米）内，平均占生长季节的50-100％，对于大多数分类为过渡性湿地的井场，则为25-100％，且{美元} <{美元}，其中25％归类为高地。几乎在样带A，B和C的整个长度上，土壤都被归类为酸性。断面D的一半以上具有非水土。除B样带外，基于每个参数确定的湿地边界是不同的，但考虑到样带的长度和分析过程中的某些假设，其边界非常接近。除样带B以外，各个湿地-高地边界的海拔高度从北向南沿48公里过渡带减小。一种基于3个参数确定湿地边界的方法具有3种替代方法来划定边界，应得出更大的结果放置精度。

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