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首页> 外文学位 >Riparian forest vegetation patterns and historic channel dynamics of the Big Sioux River, South Dakota.
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Riparian forest vegetation patterns and historic channel dynamics of the Big Sioux River, South Dakota.

机译：南达科他州大苏河的河岸森林植被格局和历史河道动态。

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摘要

The Big Sioux River, a major tributary to the Missouri River, drains approximately 22,550 km2 in South Dakota, Iowa, and Minnesota. Compared to many other Great Plains rivers, the Big Sioux is relatively natural and free-flowing, with a largely intact riparian corridor and little flow regulation. Along its course, the river flows through a largely agriculturally dominated matrix that contains several major population centers. The close proximity to these agricultural and urban land uses have contributed to a number of water quality problems during the last 50 years that have threatened the ecologically integrity of the Big Sioux. In order to conserve and properly manage the Big Sioux corridor, it will be important to gain an improved scientific understanding of ecological patterns and their environmental correlatives along the river. This thesis is an attempt to provide these data.;Using modern aerial imagery and ground-truthing techniques, I quantified the current extent of riparian forest communities along a 576 km stretch of the Big Sioux River. In total, there were 7 dominant riparian forest community types along the river that contributed to 6.85% of the total Big Sioux basin land cover. Riparian forest extent increased from north to south and was dominated by the Silver Maple-Elm-Cottonwood Forest community type (41% of total). In addition, 35 riparian forest sites and 5 upland forest sites were sampled to examine the typical vegetative characteristics of forest within the basin. In general, floristic quality and basal area decreased from south to north and % exotics increased. These findings provided data on riparian forest habitats along the river and can be used to assess future forest restoration efforts.;Streamflow has increased dramatically over the last 30 years in the Big Sioux basin (122% increase in mean annual flow) resulting in a highly significant, 62% increase in channel planform area, a 4% decrease in channel length and sinuosity, and a 69% increase in channel width. These channel adjustments were highly correlated with increasing mean annual flows and baseflow. To examine why these increases have occurred, the relative effects of land use change and climatic variation were examined, with findings from these analyses lending support towards land use change, specifically agricultural intensification, being a more important driver of increased streamflow and channel adjustments than changes in the climatic regime. These results are in line with findings from similar studies of agriculturally dominated basins throughout the Upper Midwest.;The final chapter examines potential pitfalls and uncertainties associated with using the Floristic Quality Assessment (FQA) across state boundaries. In total, results from 18 riparian and upland forest sites along the South Dakota/Iowa border were compared using Coefficients of Conservatism (C-values) from each state. Findings indicated that for the 141 observed species, South Dakota mean C-values were higher (3.57) than Iowa (2.50) and that there were 98 C-value divergences between states with 20 being equal to +/- 4. FQA values calculated using Iowa C-values were consistently lower than South Dakota and highlight the subjective nature of assigning C-values at the individual state level. This thesis provides several recommendations that would improve the utility of the FQA and allow it to become more widely standardized as a valuable ecological assessment tool.;This thesis provides baseline data critical to targeting current and future management efforts along the Big Sioux and provides an improved scientific understanding of ecological patterns in habitats along this valuable watershed in eastern South Dakota and northwestern Iowa.
机译：大苏河是密苏里河的主要支流，在南达科他州，爱荷华州和明尼苏达州的排水量约为22,550平方公里。与其他许多大平原河相比，大苏河相对自然且自由流动，河岸走廊基本完好，流量调节很少。在这条河中，这条河流经一个以农业为主的矩阵，其中包含几个主要的人口中心。在过去的50年中，这些农业和城市土地的使用非常接近，导致了许多水质问题，这些问题已经威胁到大苏族的生态完整性。为了保护和妥善管理大苏城走廊，重要的是要对沿河的生态模式及其与环境的相关性有更好的科学了解。本论文试图提供这些数据。我利用现代航空影像和地面实地技术，对大苏河576公里处的河岸森林群落的当前范围进行了量化。沿河共有7种主要的河岸森林群落类型，占大苏河盆地土地覆盖总量的6.85％。河岸带森林面积从北向南增加，主要由银枫-榆木-卡顿伍德森林群落类型（占总数的41％）主导。此外，还采样了35个河岸林地和5个山地林地，以研究流域内森林的典型营养特征。一般而言，植物种类质量和基础面积从南到北下降，外来植物百分比增加。这些发现提供了沿河沿岸森林栖息地的数据，可用于评估未来的森林恢复工作。在过去30年中，大苏流域的流量急剧增加（年均流量增加122％），从而导致显着的是，通道平面面积增加了62％，通道长度和弯曲度降低了4％，通道宽度增加了69％。这些渠道调整与年均流量和基准流量的增加高度相关。为了检查为什么会出现这些增加，研究了土地利用变化和气候变化的相对影响，这些分析的发现为土地利用变化（特别是农业集约化）提供了支持，是增加流量和调整河道的重要驱动力。在气候体制下。这些结果与对整个中西部地区农业为主的盆地进行的类似研究得出的结论相一致。最后一章探讨了跨州使用植物质量评估（FQA）可能带来的陷阱和不确定性。总体上，使用每个州的保守系数（C值）比较了南达科他州/爱荷华州边界沿岸的18个河岸和山地森林地点的结果。结果表明，对于141个观察到的物种，南达科他州的平均C值（3.57）比爱荷华州的（2.50）高，并且各州之间的C值差异为98，其中20个等于+/- 4。爱荷华州的C值始终低于南达科他州，并且突显了在各个州一级分配C值的主观性质。本文提出了一些建议，这些建议将改善FQA的效用，使其成为有价值的生态评估工具而更加广泛地标准化。；本论文提供了基准数据，这些数据对于在Big Sioux上当前和将来的管理工作有针对性，并且提供了改进的方法。对南达科他州东部和爱荷华州西北部这一重要流域沿线栖息地生态模式的科学理解。

著录项

  • 作者

    Ley, Matt J.;

  • 作者单位

    University of South Dakota.;

  • 授予单位 University of South Dakota.;
  • 学科 Environmental Management.;Natural Resource Management.;Water Resource Management.
  • 学位 M.S.
  • 年度 2012
  • 页码 201 p.
  • 总页数 201
  • 原文格式 PDF
  • 正文语种 eng
  • 中图分类
  • 关键词

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