Examining the role of habitat quality in determining river ecosystem resilience to extreme flood events

检查栖息地质量在确定河流生态系统对极端洪水事件的恢复能力中的作用

• 批准号: 2109092
• 金额: --
• 依托单位: University of Leeds
• 依托单位国家: 英国
• 项目类别: Studentship
• 财政年份: 2018
• 资助国家: 英国
• 起止时间: 2018 至 无数据
• 项目状态: 已结题
• 来源: https://gtr.ukri.org/projects?ref=studentship-2109092
• 关键词: Examining; role; habitat; quality; determining

Extreme flood events have occurred more frequently in recent years throughout the UK due to changing weather patterns, and are predicted to further increase in regularity. Although floods naturally maintain ecosystem diversity and redistribute energy, nutrients, sediments & biota, extreme floods can significantly impact river ecosystem biodiversity, ecosystem functioning & instream habitat quality. Understanding these impacts on river ecosystems is a major priority for the Environment Agency (EA) who are under pressure to balance competing needs of environmental protection policy (e.g. EU WFD, EU Habitats Directive) with pressures from government, businesses and the public for adequate flood protection.Limited evidence suggests that river ecosystem resilience to extreme floods is dependent on instream geomorphic complexity and to the magnitude and timing of previous high flow events. However, instream habitat modifications are extensive throughout England, with 52% of lowland & 42% of upland rivers affected by bank reinforcement and/or re-sectioning largely for flood protection. This habitat alteration has contributed to widespread failures of UK rivers under the EU WFD.Recent advances in river habitat modelling have allowed the extrapolation of semi-quantitative survey data of habitat modification throughout England's river networks. Large-scale habitat quality & river modification data can now be paired with long-term flow and ecology datasets, to test how habitat alteration may influence the ecological quality of the river ecosystem & resilience to extreme events. Data held by the EA (co-located macroinvertebrate samples, river habitat survey (RHS) & river flow data) consists of >12 years of continuous data from >16000 sites thereby affording possibilities for advanced statistical modelling of the resilience of macroinvertebrate populations (e.g. persistence, extinction, invasion) and community assembly/disassembly responses to floods. A pilot data-matching exercise on the dataset identified 37 sites in the North West area alone where flood, invertebrate and RHS data were sufficiently temporally and spatially paried to allow the use of these sites in a statistical model, thus proving the applicability of this dataset & approach. The addition of long-term river flow data from EA gauges (available via CEH's NRFA database and via the EA) to identify extreme flow events, in combination with additional collection of macroinvertebrate and RHS data by the student to validate & extend database records will allow the unique opportunity to identify flow thresholds (flow magnitudes or durations from long term flow data above which invertebrate communities may not recover from), flood-sensitive species or habitats for monitoring flood recovery. This would provide a predictive capacity of how river restoration efforts could mitigate high flow impacts through the provision of flow refugia.Using this approach, the student will be able to test the following hypotheses; (1) habitat alteration & loss of complexity reduces the resilience of macroinvertebrate communities to extreme flood events, (2) RHS habitat quality indices can be used to predict macroinvertebrate community recovery and resilience to flooding events; (3) relationships between ecological community resilience measures and habitat alteration indices can inform guidelines for appropriate management and restoration approaches to mitigate flood effects.

近年来，由于天气模式的变化，英国各地极端洪水事件发生的频率越来越高，预计其频率将进一步增加。尽管洪水自然地维持了生态系统的多样性并重新分配了能量、养分、沉积物和生物群，但极端洪水会严重影响河流生态系统的生物多样性、生态系统功能和河内栖息地质量。了解这些对河流生态系统的影响是环境署 (EA) 的首要任务。环境署面临着平衡环境保护政策（例如欧盟 WFD、欧盟人居指令）的相互竞争需求与政府、企业和公众要求充分防洪的压力的压力。有限的证据表明，河流生态系统对极端洪水的恢复能力取决于河流内地貌的复杂性以及之前高流量事件的规模和时间。然而，整个英格兰河内栖息地的改造十分广泛，52% 的低地河流和 42% 的高地河流受到河岸加固和/或重新分区的影响，主要是为了防洪。这种栖息地改变导致了欧盟 WFD 下英国河流的广泛衰竭。河流栖息地模型的最新进展使得可以对整个英格兰河流网络的栖息地改变的半定量调查数据进行推断。大规模栖息地质量和河流改造数据现在可以与长期流量和生态数据集配对，以测试栖息地改变如何影响河流生态系统的生态质量和极端事件的恢复能力。环境署持有的数据（同一地点的大型无脊椎动物样本、河流栖息地调查 (RHS) 和河流流量数据）由来自超过 16000 个地点的超过 12 年的连续数据组成，从而为大型无脊椎动物种群的恢复力（例如持久性、灭绝、入侵）和群落组装/解体对洪水的反应提供了先进的统计模型。对数据集进行的试点数据匹配工作仅在西北地区就确定了 37 个地点，其中洪水、无脊椎动物和 RHS 数据在时间和空间上进行了充分匹配，允许在统计模型中使用这些地点，从而证明了该数据集和方法的适用性。添加来自 EA 测量仪的长期河流流量数据（可通过 CEH 的 NRFA 数据库和 EA 获得）来识别极端流量事件，结合学生额外收集的大型无脊椎动物和 RHS 数据来验证和扩展数据库记录，将提供独特的机会来确定流量阈值（来自长期流量数据的流量大小或持续时间，超过该阈值，无脊椎动物群落可能无法恢复）、洪水敏感物种或栖息地 监测洪水恢复。这将提供河流恢复工作如何通过提供流量避难所来减轻高流量影响的预测能力。使用这种方法，学生将能够测试以下假设； (1) 栖息地改变和复杂性丧失降低了大型无脊椎动物群落对极端洪水事件的恢复能力，(2) RHS 栖息地质量指数可用于预测大型无脊椎动物群落的恢复和对洪水事件的恢复能力； (3) 生态群落复原力措施和栖息地改变指数之间的关系可以为适当的管理和恢复方法提供指导，以减轻洪水影响。