LTREB: Collaborative Research - River ecosystem responses to floodplain restoration

蒙大拿州西部的克拉克福克河上游有采矿污染和洪水的遗留问题。一项耗资2亿美元的河流生态修复计划于2013年启动，将持续20年。20多年来，国家机构和科学家们收集了有关这条河的水化学、河底生长的藻类以及沿280公里河流的金属污染的丰度和分布的数据。这些核心数据集捕获了一条高度受损河流的历史，但随着时间的推移，负责这些数据集的大部分资金和人员都已流失。本研究扩展并利用这些长期监测数据，以解决河流的物理形态和生物过程如何响应不断变化的营养丰度和大规模洪泛平原恢复的同时影响。对河流过去和未来动态的比较为研究人员提供了一个机会，以解决生态学的基本理论，以应对范围内罕见的系统操纵。该研究将为理解大规模河漫滩恢复的影响提供一个框架，这将适用于未来的河流工程。教育和推广活动将包括为本科生实习生建立一个研究培训计划，指导美国原住民本科REU参与者，与克拉克福克流域教育计划合作，并与克拉克福克河沿岸农村社区的五年级科学班一起制定一个项目。修复将包括去除含金属的洪泛区土壤，将洪泛区降低到原来的高度，以便在洪水期间更容易与河流相连，并在离污染源最近的70多公里的洪泛区重新种植植被。本研究将产生数据来验证恢复将改变河流生态系统结构和功能的假设，因为恢复响应将反映洪泛区尾矿的清除，洪泛区连通性的重建以及上游营养物质输入的减少。此外，该研究将测量排水网络上游河段的变化将如何改变下游河段的能量和材料的纵向梯度。该研究将重新建立对沉积物中无机磷和氮浓度、底栖有机物储量和总可回收金属的监测。无机氮同位素特征的纵向调查将用于追踪营养源的变化。历史监测将通过荧光光谱表征来跟踪溶解有机碳浓度和组成，并通过实验来解决碳组成如何影响金属生物利用度。水下自主系泊仪器的使用将提供pH值、氧气和二氧化碳的高分辨率测量，这些测量将用于生成河流代谢（初级生产和呼吸）模型，以便将功能变化与改变的化学和生物环境联系起来。这些努力将为解决克拉克福克河上游的生态变化提供机会，在与景观恢复相称的时间和空间尺度上。

The Upper Clark Fork River in western Montana has a legacy of mining pollution and flooding. A $200 million-dollar ecological restoration of the river was initiated in 2013 and will continue for 20 years. For over 20 years, state agencies and scientists have gathered data on the river's water chemistry, the algae that grow on the river bottom, and the abundance and distribution of metal contamination along 280 km of the river. These core data sets have captured the history of a highly impaired river, but most of the funding and personnel responsible for these data sets have been lost over time This research extends and capitalizes on these long-term monitoring data to address how the river's physical forms and biological processes will respond to the simultaneous influences of changing nutrient abundance and large-scale floodplain restoration. Comparisons of past and future dynamics of the river provide an opportunity for the researchers to address fundamental theories of ecology in response to a system manipulation that is rare in scope. The research will provide a framework for understanding effects of large-scale floodplain restoration that will be applicable to future river projects. Educational and outreach activities will include the establishment of a research training program for undergraduate interns, mentoring Native American undergraduate REU participants, working with a the Clark Fork Watershed Education Program, and developing a project with 5th grade science classes in rural communities along the Clark Fork River. Restoration will include removal of metal-laden floodplain soils, lowering of the floodplain to its original elevation where it will be more readily connected to the river during flooding, and re-vegetation of over 70 km of the river's floodplain closest to contaminant sources. This research will generate data to test the hypothesis that restoration will change the river ecosystem structure and function because restoration responses will reflect removal of floodplain tailings, reestablished floodplain connectivity, and reduced nutrient inputs to upstream reaches. Additionally, the research will measure how changes to upstream reaches within the drainage network will alter longitudinal gradients in energy and materials available to downstream river segments. The research will re-establish monitoring of inorganic phosphorus and nitrogen concentrations, benthic organic matter stocks, and total recoverable metals in depositional sediments. Longitudinal surveys of isotopic signatures for inorganic nitrogen will be used to track changing nutrient sources. Historical monitoring will be augmented with tracking of dissolved organic carbon concentration and composition using characterization by fluorescent spectroscopy, along with experiments to address how carbon composition influences metal bioavailability. Use of Submersible Autonomous Moored Instruments will provide high-resolution measures of pH, oxygen, and carbon dioxide that will be used to generate models of river metabolism (primary production and respiration) in order to link functional changes to altered chemical and biological environments. Together these efforts will provide opportunities to address the ecological changes in the Upper Clark Fork River over a temporal and spatial scale commensurate with landscape restoration.