Doctoral Dissertation Research: Influence of Grazing Differences on Stream Geomorphology in Tallgrass Prairie Headwater Streams

本论文项目是关于确定不同的牛和野牛放牧方式如何影响沉积物污染和运输的草地溪流。尽管放牧是一种常见的土地利用方式，但人们对不同的放牧方式如何影响流经这些土地的河流中的沉积物动态知之甚少。由于物种特有的生理和行为差异（如打滚、需水量、耐热性、植被偏好），不同种类的放牧动物可能会产生显著不同的沉积物输入。研究人员期望发现，由于斜坡侵蚀和践踏对河床的干扰增加，放牧流域的泥沙负荷和河床输沙事件的频率和强度将显著增加。据预测，牛放牧的流域比野牛放牧的流域具有更高的泥沙负荷，因为牛的行为习惯可能对河道产生更直接的影响和干扰。该项目将促进对生理和行为差异如何驱动物种特异性影响的理解，并有助于形成地貌生物工程或生物地貌学的越来越多的文献。沉积物是影响美国河流的主要污染物之一。高泥沙负荷导致整个北美和世界的水库填满，并被认为是沿海系统中氧气消耗的主要来源。在北美大平原地区，径流和山坡侵蚀率的增加导致水质下降，淡水的社会和经济价值下降。本项目的研究成果将为草原河流的保护、恢复和管理实践提供参考。特别是，研究结果可以作为修订放牧最佳管理做法的基础，以解决该区域内的水质问题。研究结果将在国家和地方科学和政策导向的学术会议上发表，提交给负责牧场管理的州和地区机构，并在同行评审的科学和管理导向的期刊上发表。作为博士论文研究进步奖，该项目将为有前途的学者提供支持。它还将为其他一些学生提供培训，其中包括来自少数民族、妇女和退伍军人等代表性不足群体的学生。

This dissertation project is about determining how various cattle and bison grazing practices influence sediment pollution and transport in grassland streams. Although grazing is a common land use practice, little is known about how different grazing practices affect sediment dynamics in the streams that drain these lands. Different species of grazing animals may produce significantly different sediment inputs to streams due to species-specific physiological and behavioral differences (e.g. wallowing, water demand, heat tolerance, vegetation preference). The researchers expect to find that grazed watersheds will have significantly higher sediment loads and higher frequencies and magnitudes of stream-bed sediment transport events because of increased hillslope erosion and stream-bed disturbance from trampling. Cattle grazed watersheds are predicted to have higher sediment loads than bison grazed watersheds because the behavioral habits of cattle are likely to produce more direct impacts and disturbances to channels. This project will advance the understanding of how species-specific impacts are driven by physiological and behavioral differences and contribute to a growing body of literature on biological engineering of landforms, or bio-geomorphology. Sediment is one of the major pollutants impacting streams in the United States. High sediment loads have led to reservoir filling throughout North America and the world and are implicated as a major source of oxygen depletion in coastal systems. In the Great Plains region of North America, increased runoff and hillslope erosion rates have led to decreased water quality and decreased the social and economic value of freshwaters. Results of this project will help to inform conservation, restoration, and management practices of grassland streams. In particular, the results could serve as the basis for revised grazing best management practices to address water quality issues within the region. The results will be presented at national and local science and policy-oriented academic conferences, presented to state and regional agencies charged with grazing land management, and published in peer-reviewed scientific and management oriented journals. As a doctoral Dissertation Research Improvement award, this project will provide support to enable a promising scholar. It will also provide training for a number of other students including several from underrepresented groups including minorities, women, and military veterans.