SG: RUI: Resilience of mountain lakes across a gradient of glacial retreat and vegetation advance

世界各地的山地景观，长期以来被认为是环境变化的哨兵，随着冰川退缩和植被上坡而迅速变化。这些景观中的原始湖泊，特别是那些因其标志性的美丽而被指定为世界遗产的湖泊，具有很强的旅游吸引力。然而，这种美丽正受到湖水清澈度变化的威胁。对这些潜在脆弱生态系统的保护工作将受益于对湖泊对全球气候变化反应的预测性理解。本研究探讨了这些景观水平变化对湖泊生态系统的影响。这些研究人员将代替长期研究单一系统的方法，对目前在集水区冰川和植被覆盖范围上存在差异的湖泊生态系统进行比较。这项研究的主要目的是比较湖泊对雨水和融雪驱动的物质输入的响应，这些物质包括冰川粉、冰川细磨岩石和有机物分解的溶解产物。这两种物质都对水体的清晰度或透明度有很强的影响，进而影响湖泊生态系统功能的许多方面。湖泊的反应将使用两种互补的生态恢复力测量来检验：抵抗，即降雨或融雪事件后系统变化的幅度；恢复是指恢复到先前状态的比率。项目发现将加深对落基山脉湖泊生态系统景观变化影响的基本科学认识。本科生将参与研究的所有阶段，包括计划、数据收集、分析和发表。将有针对性地吸引来自不同背景和经历的学生。由于山区湖泊的水透明度是一个强有力的案例研究，通过它可以向更广泛的受众传达环境变化对生态系统的影响，因此将制作和分发一部描述这项研究的短片。拟议的研究将测试一个总体假设，即当湖泊集水区从冰川状态转变为岩石状态再转变为植被状态时，水透明度弹性的变化是系统地发生的。具体而言，预测水的透明度阻力随着冰川的消失而增加，随着植被的推进而降低。此外，随着透明度调节因子从冰川集水湖中的悬浮岩粉向植被集水湖中的溶解有机质（DOM）转变，水透明度的回收率预计会增加。为了验证这些假设，配备了测量浊度和DOM荧光成分的传感器的高频监测浮标将被部署在五个湖泊中，这些湖泊在冰川和植被覆盖的梯度上有所不同。同步水文数据将用于更好地了解材料输入的动态及其与附近气象站记录的气象数据的关系。更一般地说，该研究通过测试阻力和恢复是否随着冰川退缩和植被推进而独立变化来探索弹性的两个组成部分之间的关系。弹性的两个组成部分的不耦合变化的潜力是研究项目的一个独特和变革的方面。该奖项反映了美国国家科学基金会的法定使命，并通过使用基金会的知识价值和更广泛的影响审查标准进行评估，被认为值得支持。

Mountain landscapes worldwide, long considered sentinels of environmental change, are changing rapidly as glaciers retreat and vegetation advances upslope. Pristine lakes within those landscapes, especially lakes whose iconic beauty has led to their designation as World Heritage sites, have strong tourist appeal. Yet that beauty is threatened by changes to the clarity of the lake waters. Conservation efforts for these potentially fragile ecosystems would benefit from a predictive understanding of lake responses to global climate change. This research explores the consequences of these landscape-level changes for lake ecosystems. Rather than study a single system over a long time, these researchers will substitute a comparison of lake ecosystems that currently differ in the extent of glacial and vegetation coverage in the catchment. The primary aim of the research is to compare lake responses to rain and snowmelt-driven inputs of materials such as glacial flour, the finely ground rock from glaciers, and dissolved products of organic matter decomposition. Both of these materials have strong effects on the clarity of the water or water transparency, which in turn influences many aspects of lake ecosystem function. Lake responses will be examined using two complementary measurements of ecological resilience: resistance, the magnitude of change in the system following rain or snowmelt events; and recovery, the rate of return to previous conditions. Project findings will deepen the basic scientific understanding of the effects of changing landscapes on lake ecosystems in the Rocky Mountains. Undergraduate students will be engaged in all stages of the research, including planning, data collection, analysis, and publication. Targeted efforts will be made to attract students from diverse backgrounds and experiences. Because water transparency of mountain lakes is a powerful case study through which to communicate ecosystem-level effects of environmental change to a broader audience, a short film describing the research will be produced and distributed.The proposed research will test the overarching hypothesis that changes in the resilience of water transparency occur systematically as lake catchments shift from glaciated to rocky to vegetated states. Specifically, resistance of water transparency is predicted to increase with glacial loss and decrease with vegetation advance. Additionally, recovery rates of water transparency are predicted to increase as the regulator of transparency shifts from suspended rock flour in glacial catchment lakes to dissolved organic matter (DOM) in vegetated catchment lakes. To test these hypotheses, high frequency monitoring buoys equipped with sensors that measure turbidity and the fluorescent component of DOM will be deployed in five lakes that vary across a gradient of glacial and vegetation coverage. Concurrent hydrological data will be used to better understand dynamics of material inputs and their relationships to meteorological data recorded at nearby weather stations. More generally, the research probes the relationship between the two components of resilience by testing whether resistance and recovery change independently as glaciers retreat and vegetation advances. The potential for uncoupled changes in the two components of resilience is a unique and transformative aspect of the research program.This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.