Collaborative Research: Hierarchical Functioning of River Macrosystems in Temperate Steppes - From Continental to Hydrogeomorphic Patch Scales

随着全球气候变化和淡水河流和湖泊中外来动植物的影响，在更大的区域到大陆尺度的宏观系统层面上了解和管理生态系统的必要性变得越来越重要。宏观系统管理需要了解不同层次的空间复杂性（从一条河流到整个河谷）和生物组织（从种群到生态系统）如何影响河流和湖泊的功能。本研究将提供18条河流的信息，这些河流平均分布在世界上两个最大的温带草原生物群落之间：北美大平原和欧亚草原（包括蒙古）。本项目将为代表性不足的参与者提供研究经验（特别是农村和美洲原住民学生），刺激STEM项目在代表性不足（EPSCoR）的州的招聘，支持主要是本科院校的一些教师和学生，这些河流流经这些温带草原内的三种主要生态区，生物群落：山地草原灌丛、矮到高的草地和半干旱灌丛。来自美国和蒙古的科学家和学生将对这18条河流在各种水文地貌区域的结构和功能进行采样，如狭窄，蜿蜒，编织和封闭的河道部分。尽管它们在生物群系和生态区域类型上具有相似性，但大平原和蒙古草原的河流宏观系统在动物群、植物群和群落方面通过生态系统功能存在很大差异。这些变化是由于气候模式的差异、河流景观改变的程度（例如，由水坝，堤坝，和河岸修改），和自然的居民动物。例如，美国的大多数河流都有一些水坝，许多外来动物也被引入，而蒙古的绝大多数河流没有水坝，它们的水生动物几乎完全是天然的，与美国的水生动物不同。此外，蒙古的中亚次大陆地区是地球上最强烈的变暖信号之一，气温上升速度比整个北方平均水平快三倍。因此，在美国的河流宏观系统可以帮助预测蒙古河流的变化，作为一个悬而未决的大坝建设和可能的物种引进到一些河流，而蒙古宏观系统的响应更快的气候变化的知识，可以帮助预测未来的影响在美国河流。因此，本项目的目标是：（a）比较和对比两大洲类似生物群落和生态区中系统驱动因素和跨尺度相互作用对河流的等级尺度关系和影响;（B）评估气候变化和人为干扰对这些河流宏观系统的影响。

The need to understand and manage ecosystems at larger regional to continental scale macrosystem levels is becoming increasingly crucial with global climate changes and impacts of exotic plants and animals in freshwater rivers and lakes. Macrosystem management requires an understanding of how different levels of spatial complexity (within a stream reach to entire river valley scales) and biotic organization (populations to ecosystems) affect the functioning of rivers and lakes. The present study will provide this information for 18 rivers spread equally between the two largest temperate steppe biomes of the world: the North American Great Plains and the Euro-Asian Steppes (including those in Mongolia). This project will provide research experiences for under-represented participants (particularly rural and Native American students), stimulate STEM program recruitment in largely under-represented (EPSCoR) states, support some faculty and students at primarily undergraduate institutions, and contribute to scientific education at both graduate and undergraduate institutions in two countries.These rivers flow through 3 major types of ecoregions within these temperate steppe biomes: mountain steppe shrublands, short-to-tall grasslands, and semi-arid shrublands. Scientists and students from the USA and Mongolia will sample the structure and functioning of these 18 rivers in a variety of hydrogeomorphic areas, such as constricted, meandering, braided, and anastomosing channel sections. Despite their similarity in biome and ecoregional types, the river macrosystems of the Great Plains and the Mongolian steppes vary substantially in fauna, flora, and community through ecosystem functioning. These variations result from differences in climatic patterns, the degree of riverine landscape modification (e.g., by dams, levees, and riparian modification), and the naturalness of the resident fauna. For example, most rivers in the USA contain some dams and many exotic fauna have been introduced, while the vast majority of Mongolian rivers contain no dams and their aquatic fauna is almost exclusively natural and different from those in the USA. Moreover, the Central Asian subcontinental area of Mongolia has one of the strongest warming signals on earth, with air temperatures rising three times faster than the overall northern hemisphere average. Consequently, riverine macrosystems in the USA can help predict changes to Mongolian rivers as a result of pending dam construction and possible species introductions to some rivers, while knowledge of responses of Mongolian macrosystems to more rapid climatic changes can help predict future effects in U.S. rivers. Therefore, this project's goals are to: (a) compare and contrast hierarchical scaling relationships and effects of system drivers and cross-scale interactions on rivers in similar biomes and ecoregions of the two continents; and (b) evaluate effects of climatic changes and anthropogenic disturbance to these river macrosystems.