Collaborative Research: Leaky Rivers: Nutrient Retention and Productivity in Rocky Mountain Streams Under Alternative Stable States

河流只占地球表面的一小部分，但对营养物质的运输和加工以及对维持全球生物多样性来说，其重要性不成比例。溪流中的木塞增加了营养物质的保留和鱼类产量。在森林生态系统中，人类清除堵塞物的行为很普遍，造成了“缺乏水坝”的溪流，储存营养和生产鱼类的能力有限。一个最好的例子是落基山脉南部的溪流，那里的木材清除遗产大大减少了堵塞。这个项目的问题是：堵塞的损失是否降低了源头河流的生产能力？据推测，果酱的损失使溪流中的营养物质泄漏更多，随后减少了营养物质的加工和鱼类产量。该项目将研究跨越河流梯度的堵塞和堵塞相关过程，包括古老森林中的河流，未管理的年轻森林和集中管理的森林。 这项工作将提供第一个大规模的评估果酱清除对河流生态系统的影响。这项研究可以改变目前的理解木材对河流生态系统的影响相结合的木塞的历史分布与密集测量的地球化学和生物变量在当代果酱的估计，允许扩展到整个蒸汽网络的局部尺度观测。了解堵塞的损失如何影响溪流将为森林景观中的源头溪流的资源管理提供信息。国家公园管理局和美国林务局监督着美国西部大片的林地，并试图恢复落基山脉景观的一些推断历史特征。通过加强对堵塞变化的理解，以及这些结构的地球化学和生态影响，拟议的工作将为这些管理行动提供急需的背景。 该项目还将为一名博士后学者和四名研究生提供培训。它还将为一些本科生提供研究经验。

Streams occupy a small part of Earth's surface, but are disproportionately important for transport and processing of nutrients and for maintaining global biodiversity. Logjams in streams increase retention of nutrients and fish production. Human removal of logjams is pervasive in forested ecosystems, creating "dam-impoverished" streams with limited capacity to store nutrients and produce fish. A prime example is streams of the southern Rocky Mountains, where a legacy of wood removal has greatly reduced logjams. This project asks: Does the loss of jams reduce the productive capacity of headwater streams? It is hypothesized that the loss of jams makes streams more leaky of nutrients, with subsequent decreased nutrient processing and fish production. This project will examine logjams and jam-associated processes across a gradient of streams, including streams in old-growth forests, unmanaged younger forests, and intensively managed forests. This work will provide the first landscape-scale assessment of the effects of jam removal on stream ecosystems. This research can transform current understanding of wood effects on stream ecosystems by combining estimates of logjam historical distribution with intensively measured geochemical and biological variables in contemporary jams, allowing extension of local-scale observations to entire steam networks. Understanding how the loss of jams affects streams will inform resource management of headwater streams in forested landscapes. The National Park Service and the US Forest Service oversee vast tracts of forested lands in the American West and are attempting to restore some of the inferred historical characteristics of the Rocky Mountain landscape. By enhancing understanding of changes in jams, as well as the biogeochemical and ecological influence of these structures, the proposed work will provide much-needed context for these management actions. This project will also provide training for one post-doctoral scholar and four graduate students. It will also provide research experiences for several undergraduate students.