T US National Park Service (NPS) was established over a century ago to conserve natural and cultural resources. As the first system of federally protected areas in the world, US national parks have shaped a global standard for protected areas. Since NPS’s inception, the US population has more than tripled, road and aircraft traffic have become widespread, and 80% of the US population now lives in urban areas (Barber et al. 2010). In this context, national parks represent refuges of ecological integrity and provide increasingly important opportunities for people to establish personal connections with natural environments (Miller 2005; Machlis and McNutt 2015). This rapid increase in infrastructure, transportation networks, and human activity has resulted in the widespread distribution of anthropogenic noise (hereafter “noise”), even in the most remote protected areas of the US (Figure 1; Buxton et al. 2017a). At high levels of exposure, noise annoys people and contributes to health problems (Basner et al. 2014). At lower levels of exposure, noise reduces the benefits of experiencing natural sounds, which include increased relaxation, restored attention, improved mood, and reduced stress (Benfield et al. 2014; Abbott et al. 2016). Noise also affects wildlife, masking critical sounds (including incidental signals such as the sound of predators approaching) and increasing perceived risk, causing changes in behavior, physiology, and fitness (reviewed in Shannon et al. [2016]). Moreover, the responses of individual species to noise extend through ecological interactions to alter community structure and ecosystem function (Francis et al. 2012). Despite its known impacts on natural systems, noise is rarely considered alongside other pervasive threats to protected areas (Butchart et al. 2010). Congressional concerns about noise in national parks have been expressed through legislation since 1975, and NPS policy requires the management of noise and conservation of acoustic resources (NPS 2006). Accordingly, NPS has been identifying noise sources, measuring not only how often they are heard but also sound levels at hundreds of sites over the past two decades, resulting in a unique, spatially diverse acoustic dataset. This study is the first comprehensive analysis of all noise sources in national parks across the US. More specifically, we identify the causes of continentalscale patterns of noise exposure (Buxton et al. 2017a) by analyzing the identities and characteristics of noise sources audible in national park units and relating these outputs to landscapescale summaries of acoustic conditions inside national parks. The results document (1) the loudest and most frequent sources of noise and the anthropogenic features associated with them, (2) which of these sources predict landscape levels of noise estimated using geospatial models, and (3) summaries of these noise metrics across different protection categories (ie park type, wilderness areas, and critical habitat of US endangered species). We relate this diagnosis of noise across different park contexts with emerging approaches to mitigate noise pollution, aiming to identify management strategies that preserve or restore natural soundscape experiences for park visitors and wildlife.

中文翻译：

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美国国家公园的人为噪声——来源和空间范围

美国国家公园管理局 (NPS) 成立于一个多世纪以前，旨在保护自然和文化资源。作为世界上第一个联邦保护区系统，美国国家公园已经形成了保护区的全球标准。自 NPS 成立以来，美国人口增加了两倍多，道路和飞机交通变得普遍，现在 80% 的美国人口居住在城市地区（Barber 等人，2010 年）。在这种情况下，国家公园代表了生态完整性的避难所，并为人们与自然环境建立个人联系提供了越来越重要的机会（Miller 2005；Machlis 和 McNutt 2015）。基础设施、交通网络和人类活动的快速增长导致人为噪声（以下简称“噪声”）的广泛分布，即使在美国最偏远的保护区（图 1；Buxton 等人，2017a）。在高水平接触下，噪音会惹恼人们并导致健康问题（Basner 等人，2014 年）。在较低的暴露水平下，噪音会降低体验自然声音的好处，包括增加放松、恢复注意力、改善情绪和减轻压力（Benfield 等人，2014 年；Abbott 等人，2016 年）。噪音也会影响野生动物，掩盖关键声音（包括捕食者接近的声音等偶然信号）并增加感知风险，导致行为、生理和健康的变化（Shannon 等人 [2016] 综述）。此外，个体物种对噪音的反应通过生态相互作用扩展到改变群落结构和生态系统功能（Francis 等人，2012 年）。尽管噪音对自然系统的影响是众所周知的，但很少将噪音与保护区的其他普遍威胁一起考虑（Butchart 等人，2010 年）。自 1975 年以来，国会通过立法表达了对国家公园噪音的担忧，并且 NPS 政策要求管理噪音和保护声学资源（NPS 2006）。因此，NPS 一直在识别噪声源，在过去的二十年中，不仅测量它们被听到的频率，而且测量数百个地点的声级，从而产生了一个独特的、空间多样化的声学数据集。这项研究是对美国国家公园内所有噪声源的首次综合分析。更具体地说，我们确定了大陆尺度噪声暴露模式的原因（Buxton et al. 2017a) 通过分析国家公园单元中可听到的噪声源的特性和特征，并将这些输出与国家公园内声学条件的景观尺度摘要相关联。结果记录了 (1) 最响亮和最频繁的噪声源以及与之相关的人为特征，(2) 这些源中的哪些可以预测使用地理空间模型估计的噪声的景观水平，以及 (3) 不同环境中这些噪声指标的摘要保护类别（即公园类型、荒野地区和美国濒危物种的重要栖息地）。我们将不同公园环境中的噪音诊断与减轻噪音污染的新兴方法联系起来，旨在确定保护或恢复公园游客和野生动物自然声景体验的管理策略。