Beaver ponds: Influence on peatland ecohydrology

我们对18世纪到19世纪海狸的区域迁移对整个北美湿地和河流生态系统造成的整体变化知之甚少。这是因为我们几乎所有的水文调查都是在他们缺席的情况下进行的。在过去的90年里，海狸的数量被认为在北美的大部分栖息地重新出现，但密度只有历史规模的10%左右。海狸的灭绝和部分种群的恢复对湿地、河流、流域和景观尺度的水文过程有什么长期影响？控制河流流量和湿地固碳能力的水文过程是否已经恢复？它们会永远改变吗？不知道这些基本问题的答案，是我们对未来不确定气候下潜在供水风险的理解上的一个巨大漏洞。这一建议的重点是探索河狸如何影响位于山谷底部的泥炭形成湿地的地表水和地下水之间的相互作用途径。我们将结合实地观察、水文和水化学实验以及水文模型来解决一般问题，例如：泥炭地海狸池塘下的冲积含水层是否有集中补给？储存在海狸池塘中的水量会影响含水层的补给吗？海狸池塘是否为泥炭地创造了有利于其持续碳积累的水文条件？这些研究将在加拿大最缺水的流域之一——弓河流域进行。这里提出的工作从基本的角度解决了其中的几个问题，并将进一步加深我们对海狸如何影响山谷地表水和地下水分配的理解-科学需要为改进供水模式和湿地管理政策的发展提供信息。该提案包括通过博士后培养本科生形式的高素质人才，使他们成为加拿大未来劳动力的领导者。

We know little about the overall changes to wetland and riverine ecosystems throughout North America that were caused by the regional removal of beavers in the 1700s to 1900. This is because nearly all of our hydrological investigations have been conducted in their absence. The beaver population is thought to have re-populated most of its North American habitat over the last 90 years - but at a density of only about 10% of its historical size. What have been the long term effects on wetland-, stream-, watershed- and landscape-scale hydrological processes from beaver extirpation and partial re-population? Have hydrological processes governing the flow regime of rivers and carbon sequestration capacity of wetlands recovered? Are they permanently changed? Not knowing the answers to these fundamental questions is a gaping hole in our understanding of potential water supply risk in the future uncertain climate. This proposal focuses on exploring how beavers influence the interactive pathways between surface and ground waters in peat-forming wetlands located in mountain valley-bottoms. We will use a combination of field observations, hydrological and hydrochemical experiments and hydrological modelling to address general questions such as: Is there focused recharge of alluvial aquifers beneath peatland beaver ponds? Does the amount of water stored in beaver ponds affect aquifer recharge? Do beaver ponds create hydrologic conditions in peatlands conducive for their continued carbon accumulation? The studies will take place in one of the most water-stressed basins in Canada - the Bow River watershed. The work proposed here addresses several of these questions from a fundamental perspective, and will further our understanding of how beaver influence the apportionment of surface water and groundwater in mountain valleys - science needed to inform the development of improved water supply models and wetland management policy. This proposal involves extension training of highly qualified personnel in the form of undergraduates through postdoctoral fellows, preparing them to become the leaders of Canada's future workforce.