Geomorphic influence of beaver on fluvial systems in the greater Yellowstone ecosystem

该奖项是根据2009年《美国复苏和再投资法案》(Public Law 111-5)提供资金的。人们一直认为，当海狸在小河流系统上修建水坝时，会导致河谷长期被泥沙填满，并创造出宽阔平坦的“海狸草场”。因此，海狸活动被认为既促进了沉积物通量的持续减少，也促进了累积沉积物中更大的地下水储存能力。通过降低流速，单独的河狸池塘明显地捕获了泥沙，但河狸水坝造成的泥沙沉积的深度和空间分布从未在比单个海狸池塘的寿命更长的时间尺度上得到量化。该项目的目标是记录大黄石地区小河流泛滥平原上的海狸水坝对沉积物的影响，这些沉积物可以追溯到大约12,000年前的最后一次冰川末期(全新世)。通过详细描述现代河狸塘沉积物及其相关地貌的结构、矿物和有机成分、化学成分和沉积结构，这项工作将确定在较老的泛滥平原层序和废弃河道中识别这些沉积物所必需的诊断特征。放射性碳测年将把海狸-池塘沉积的时间放在黄石地区长期环境变化的背景下。从这项研究中获得的关于海狸筑坝的长期影响的知识，对于理解溪谷的长期演变具有重要意义。它还与改善小溪系统的整体健康有关，例如在河狸数量下降导致河道切割显著增加的那些系统。因此，这将有助于将恢复和保护溪流栖息地和水质的现有资源集中在最需要的水道上。这些信息与黄石国家公园北部的管理特别相关，在那里，缺乏海狸筑坝被认为导致许多溪流被削减，从而导致地下水位下降和湿地栖息地减少。这项研究将涉及独立研究项目和对两名研究生的高级科学培训。此外，新墨西哥大学盖洛普校区以美国原住民为主的本科生将参与实地和实验室研究，这将有助于这些学生进入科学学位课程和职业生涯。

This award is funded under the American Recovery and Reinvestment Act of 2009 (Public Law 111-5).It has been assumed that when beavers build their dams across small stream systems it causes long-term filling of valleys with sediment and creates broad, flat "beaver meadows". Thus beaver activity is thought to promote both a persistent reduction in sediment flux and greater groundwater storage capacity in the accumulated deposits. By reducing flow velocities, individual beaver ponds clearly trap sediment, but the depth and spatial distribution of sediment deposition caused by beaver dams have never been quantified over timescales longer than the lifetime of a single beaver pond. The goal of this project is to document the effects of beaver dams in floodplains of small streams in the greater Yellowstone area, in deposits dating from the present back to the end of the last glaciation about 12,000 years ago (the Holocene epoch). By detailing the texture, mineral and organic composition, chemistry, and sedimentary structures of modern beaver-pond deposits and their associated landforms, this work will define diagnostic characteristics essential to identifying these deposits in older floodplain sequences and abandoned channels. Radiocarbon dating will put the timing of beaver-pond deposits in the context of long-term environmental change in the Yellowstone region. Knowledge gained in this study about the long-term effects of beaver damming is of significance in understanding the long-term evolution of stream valleys. It also has relevance to improving the overall health of small stream systems, such as those where a decline in beaver populations has caused a notable increase in channel incision. It will thus help to focus available resources for restoring and protecting stream habitat and water quality on those waterways that are most in need. Such information is particularly relevant to management in northern Yellowstone National Park, where a lack of beaver damming is thought to have caused downcutting of many streams, with consequent lowering of water tables and reduction of wetlands habitat. The study will involve independent research projects and advanced scientific training for two graduate students. In addition, undergraduate students from the predominantly Native American population at the UNM-Gallup campus will be involved in both field and laboratory research that will assist in movement of these students into scientific degree programs and careers.