东北虎豹国家公园森林声景的昼夜和季节变化

被动声学监测技术和声学指数通过对音频数据的时频域特征进行定量分析,可以反映声景的复杂度、多样性和健康程度等,已经成为评估生物多样性变化的重要手段。本研究从2020年6月至2021年6月在东北虎豹国家公园采集了52个点的声学数据,计算了春、夏、秋、冬4个季节和黎明、白天、黄昏、夜晚4个昼夜时间段的声音复杂度指数(acoustic complexity index,ACI)、声音多样性指数(acoustic diversity index,ADI)、声音均匀度指数(acoustic evenness index,AEI)、生物声学指数(bioacoustic index,BIO)、标准化声景差异指数(normalized difference soundscape index,NDSI)、声音熵指数(acoustic entropy index,H)和1–21k Hz共20个频段的功率谱密度(power spectral density,PSD)等声学指数,评价了声景构成和多样性的昼夜和季节性差异。结果表明,东北虎豹国家公园的声景随季节变化具有显著的昼夜节律差异,尤其是夜晚的声景和声学成分...     

鸟类迁徙对图们江下游湿地声景时间格局的影响

声景生态学是一个相对较新和快速发展的研究领域,被动声学监测技术和声学指数已经成为研究湿地鸟类和声景多样性的重要方法。本研究评价了鸟类迁徙对中国东北图们江流域下游湿地声景日、月和季节变化的影响。我们从2020年11月至2021年12月在图们江下游敬信湿地设置10个采样点,获得91,988条时长5min的有效音频,计算了声音复杂度指数(acoustic complexity index,ACI)、生物声学指数(bioacoustic index,BIO)、声音均匀度指数(acoustic evenness index,AEI)和标准化声景差异指数(normalized difference soundscape index,NDSI)以及1–11 k Hz频段的功率谱密度(power spectral density,PSD)。结果表明,声学指数对鸟类迁徙活动敏感,其中2个迁徙期声景(2–4月和10–11月)都以1–2k Hz雁类白天的叫声为主,NDSI显著降低,1–2k Hz的PSD显著升高,但雁类向北迁徙时几个声学指数变化更为敏感,有效地捕获了迁徙峰值,表明不同季节鸟类迁徙模式存在差异...     

海南长臂猿生境的声景观与声学活动评估

海南霸王岭自然保护区是中国唯一保护海南长臂猿及其生存环境的国家级自然保护区,具有海南长臂猿(Nomascus hainanus)声音、鸟类声音等丰富的声景资源。探究海南长臂猿生境内的声景构成及声学活动,旨在为该区域的生态保护提供技术支撑。利用被动声学监测技术采集该保护区的声音数据,通过分析不同频率范围内的声景功率分布,描述了保护区声景观的特征与日变化;基于广泛使用的4个声学指数ACI(acoustic complex index)、ADI(acoustic diversity index)、BI(bioacoustic index)、NDSI(normalized difference soundscape index)来评估海南长臂猿声音,并利用随机森林算法,以4个声学指数为预测变量,有无海南长臂猿声音为响应变量,对声音数据进行分类。结果表明：(1)不同频率范围内的声景功率反映了研究区不同的声学群落信息,具有显著的时间变化特征,表明了鸟类、海南长臂猿等动物的黎明和黄昏合唱活动,其中,1～2 kHz符合海南长臂猿的黎明合唱,2～5 kHz符合鸟类等动物的生活规律;(2)有海南长臂猿与无...     

基于多传感器的声景大数据在线采集与分析系统研究

声景包含重要的生态信息,具有实时性强、信息密度高的特点,有重要研究价值。现有的声景研究中,音频及相关环境参数采集和分析仍需要大量的人工作业,耗时耗力。基于多传感集成、边缘计算和深度学习技术,建立了一套声景大数据在线采集与分析系统,包括边缘计算节点和中心计算服务器。并通过3个实验站点,进行了近1年的技术验证,实现了声景大数据的自动化在线采集、传输和分析。该系统能适应户外恶劣的自然环境,能根据任务需求持续不断地进行声景大数据在线采集和分析,稳定性好。声学指数可以反映声景变化,但因指数侧重点不同,不同的声学指数之间变化特征差异较大,需要组合使用。通过声纹特征图能直观地识别出不同发声源,对物种的快速识别、声源的分类等具有较强的借鉴意义。系统借助VGGish网络提取的高维声景特征图能很好地识别不同站点和不同时间的声景变化,在不同站点和昼夜上具有较高的区分精度,有快速和直观地反映不同生态系统的类型特征、生态系统动态变化的潜力。丰富声纹特征库、优化声景特征分析神经网络、建设声景长期监测共享网络,有助于扩展系统在物种识别、生物多样性快速分析、生物与环境相互作用机制方面的应用。研究为声景大数据的在线采集...     

声景生态学数据分析与应用

声景生态学是研究景观中生物与非生物声音在多种时空尺度下的声学格局与过程,揭示声音与人类以及声音与自然之间关系的学科。基于声景生态学的研究内容,从声景元素解析、生物多样性评估及人类身心健康评价应用案例中,梳理了数据分析的前沿方法。结论表明,分析技术的发展,特别是人工智能技术的进步,使声景生态学的研究呈现从人工到机器、从单一特征计算到多维特征提取、从单学科研究到多学科联合分析的技术化发展趋势,不断拓展着声景生态学的研究深度与广度。同时这些分析技术的发展也急需优化和标准化,来提高方法的通用性和研究结果间的可比性。此外,需要融合生态学、计算机科学和心理学等交叉学科的理论和方法,进一步推动声景生态学数据分析技术方法体系的完善。     

声学指数在城市森林鸟类多样性评估中的应用

鸣声是鸟类之间进行沟通和传递信息的重要方式,这为通过声学监测评估鸟类多样性提供了独特的机会。利用声学指数快速评估生物多样性是一种新兴的调查方法,但城市森林中的复杂声环境可能会导致声学指数的指示结果出现偏差。为了解声学指数在城市森林中应用的可行性,本研究在北京市东郊森林公园设置了50个矩阵式调查样点,于2021年4–6月每月进行1次鸟类传统观测和同步鸣声采集,通过比较两种方法的结果来探究声学监测的有效性。采用Spearman相关分析和广义线性混合模型评估6个常用声学指数与鸟类丰富度和多度的关系,并衡量了每个指数的性能。结果表明:(1)本研究共记录到鸟类10目23科35种,通过声学监听识别的总物种数与传统鸟类观测相等,但具体鸟种存在差异;(2)不同月份间声学指数与鸟类丰富度和多度的相关性有明显差别,声学复杂度指数(ACI)和标准化声景差异指数(NDSI)优于其他指数,是评估鸟类多样性的关键变量;(3)声学指数对鸟类多度的预测能力(R²m=0.32,R2c=0.80)要高于丰富度(R²m=0.12,R2c=0.18)。声学指数为快速评估生物多样性提...     

现代生物声学的学科发展趋势及中国机遇

随着数字录音技术、电子学和微电子学、人工智能、信息科学等跨学科领域的技术革新,现代生物声学逐渐与生物学、生态学等学科及关联学科之间形成了广泛的交叉前沿领域。现阶段,现代生物声学主要以生物学、生态学等基础学科的理论方法为指导,着重于揭示环境中各类声音在生物之间以及生物与人类、环境之间的相互作用及相关科学规律,为人类认识、保护和利用生物声学资源提供理论基础和解决方案。本文重点阐述了现代生物声学的学科内涵和学科特征,介绍了动物生物声学、生态声学、水下生物声学、环境生物声学、保护生物声学、计算生物声学以及现代生物声学研究的技术框架等前沿热点和发展趋势,评估了中国生物声学研究的学科现状与发展机遇,并对未来学科建设进行了展望。     

生物声音监测研究在生物多样性领域的应用

声音是生物之间交流的重要手段,对生物声音的监测与分析是描述和评估生物多样性的新兴方法。这种方法不侵入和破坏自然环境,通过声音记录生态信息,并有效反映生物多样性的相关特征,是一种重要的生态工具。从声音角度探讨生物多样性的变化拓宽了多学科交叉的新思路,因此近年来被越来越多地应用于生态学研究中。本文阐述了利用声音监测评估生物多样性的主要理论基础和研究方法,从发声动物的生物多样性、声景的时空多样性两个方面介绍了相关领域的研究进展,列举了声音监测在评估土地利用变化、气候变化和城市化对生物多样性影响的应用实例。最后,对未来研究方向进行了展望,希望能进一步挖掘声音调查的发展潜力,为生物多样性的监测评估提供有效的借鉴和参考。     

被动声学监测技术在陆生哺乳动物研究中的应用、进展和展望

被动声学监测(passive acoustic monitoring,PAM)技术指将自动录音机安装在自然环境中收集野生动物及其所在环境的声音信号的监测方法。20世纪90年代以来,PAM技术陆续被应用于翼手目和灵长目等陆生哺乳动物的监测和研究,探究了陆生哺乳动物行为学、生态学和保护生物学等方面的科学问题。然而,当前缺乏对这些研究的系统性总结和展望。本文从活动规律和时间分配、栖息地利用、物种分布、种群大小与密度、生物多样性、人为干扰的影响等领域综述了PAM技术在陆生哺乳动物中的研究进展,并列举了相关应用实例。总体上,PAM技术涉及到生物学、生态学、声学、计算机科学等多学科的交叉融合,其应用受限于声学数据的储存和管理、物种或个体自动化识别以及声学指数评估的普适性,设备价格也相对昂贵,这些可能是导致该技术在我国陆生哺乳动物监测和研究方面的应用还相对滞后于其他国家的原因。最后,本文对未来研究方向进行了展望,并建议尽快建立和完善我国陆生哺乳动物PAM网络和数据共享平台、组织开展面对面访问调查或生物多样性保护相关的知识竞赛等公民科学项目、向更多科研机构或保护区推广PAM技术的应用,使该技术成为陆生...     

Beta声学指数的特征和应用

随着录音设备性能的提高和硬件价格的降低,基于录音评估声景来反映生境特征和生物多样性的方法得到快速发展。声学指数是对声音整体特征的量化,受到录音生境和生物组成的共同影响,因此可构建声学指数与生境特征和生物组成的关联。按照作用的尺度,声学指数可分为两类:反映录音内信息的alpha声学指数和比较不同录音之间差异的beta声学指数。随着录音设备的普及,以及在大尺度上进行生物监测工作的增加,对不同时间、不同地点的录音进行比较的需求日益迫切。因此,beta声学指数的开发和应用是声学指数研究的重要方向。本文介绍了11个常用的beta声学指数,并探讨了这些指数的数学特征(非负性、同一性、对称性、直递性、有限性)。本文还通过文献检索获取了beta声学指数在实证中的应用情况,发现研究中常使用beta声学指数反映时间节律、生境特征的差异或生物组成的改变。最后,本文指出了beta声学指数研究/应用中迫切需要发展的3个方向:开发新的指数、优化已有指数的计算方式、增加实证研究。     

Soundscape analysis and acoustic monitoring document impacts of natural gas exploration on biodiversity in a tropical forest

Natural resource extraction is increasing rapidly in tropical forests, but we lag behind in understanding the impacts of these disturbances on biodiversity. In high diversity tropical habitats, acoustic monitoring is an efficient tool for sampling a large proportion of the fauna across varied spatial and temporal scales. We used passive acoustic monitoring in a pre-montane forest in Peru to investigate how soundscape composition and richness of acoustic frequencies varied with distance from a natural gas exploratory well and with operational phase (construction and drilling). We also evaluated how anuran and avian species richness and vocal activity varied with distance and between phases. Soundscape analyses showed that acoustic frequency similarity was greatest among sites closer to (≤250 m) and farther from (≥500 m) the platform. Soundscapes revealed more frequencies were used during construction and showed a weak trend of increasing frequency richness with increasing distance from the disturbance. Avian species richness and detections increased with distance from the platform, but anuran richness and detections declined with distance. Operational phase did not play a significant role in overall richness or activity patterns of either group. Among birds, insectivore detections increased with distance from the platform, and nectarivores were detected more frequently during the drilling phase. Results demonstrate that acoustic monitoring and soundscape analyses are useful tools for evaluating the impact of development activity on the vocalizing community, and should be implemented as a best practice in monitoring biodiversity and for guiding specific mitigation strategies.     

Connecting soundscape to landscape: Which acoustic index best describes landscape configuration?

Soundscape assessment has been proposed as a remote ecological monitoring tool for measuring biodiversity, but few studies have examined how soundscape patterns vary with landscape configuration and condition. The goal of our study was to examine a suite of published acoustic indices to determine whether they provide comparable results relative to varying levels of landscape fragmentation and ecological condition in nineteen forest sites in eastern Australia. Our comparison of six acoustic indices according to time of day revealed that two indices, the acoustic complexity and the bioacoustic index, presented a similar pattern that was linked to avian song intensity, but was not related to landscape and biodiversity attributes. The diversity indices, acoustic entropy and acoustic diversity, and the normalized difference soundscape index revealed high nighttime sound, as well as a dawn and dusk chorus. These indices appear to be sensitive to nocturnal biodiversity which is abundant at night in warm, subtropical environments. We argue that there is need to better understand temporal partitioning of the soundscape by specific taxonomic groups, and this should involve integrated research on amphibians, insects and birds during a 24 h cycle. The three indices that best connected the soundscape with landscape characteristics, ecological condition and bird species richness were acoustic entropy, acoustic evenness and the normalized difference soundscape index. This study has demonstrated that remote soundscape assessment can be implemented as an ecological monitoring tool in fragmented Australian forest landscapes. However, further investigation should be dedicated to refining and/or combining existing acoustic indices and also to determine if these indices are appropriate in other landscapes and for other survey purposes.     

Time-series forecasting offers novel quantitative measure to assess loud sound event in an urban park with restored prairie

Soundscape ecology and ecoacoustics study the spatiotemporal dynamics of a soundscape and how the dynamics reflect and influence ecological processes in the environment. Soundscape analysis methods employ acoustic recording units (ARUs) that collect acoustic data in study areas over time. Analyzing these data includes computation of several acoustic diversity indices developed to quantify species abundance, richness, or habitat condition through digital audio processing and algorithm adaptations for within-group populations. However, the success of specific indices is often dependent on habitat type and biota richness present and analyzing these data can be challenging due to temporal pseudo-replication. Time-series analytical methods address the inherent problems of temporal autocorrelation for soundscape analyses challenges. Animal population dynamics fluctuate in a variety of ways due to changes in habitat or natural patterns of a landscape and chronic noise exposure, with soundscape phenology patterns evident in terrestrial and aquatic environments. Historical phenological soundscape patterns have been used to predict expected soundscape patterns in long-term studies but limited work has explored how forecasting can quantify changes in short-term studies. We evaluate how forecasting from an acoustic index can be used to quantify change in an acoustic community response to a loud, acute noise. We found that the acoustic community of a Midwestern restored prairie had decreased acoustic community activity after a loud sound event (LSE), a Civil War Reenactment, mainly driven by observed changes in the bird community and quantified using two methods: an automated acoustic index and species richness. Time-series forecasting maybe considered an underutilized tool in analyzing acoustic data whose experimental design can be flawed with temporal autocorrelation. Forecasting using auto ARIMA with acoustic indices could benefit decision makers who consider ecological questions at different time scales.     

Acoustic detection and acoustic habitat characterisation of the critically endangered white-bellied heron (Ardea insignis) in Bhutan

1. Growing developmental activities, such as hydropower construction, farm roads, and other human activities, are affecting the critically endangered white-bellied heron (WBH). Out of a known global population of 60, 28 individuals inhabit the river basin area and freshwater lakes and ponds of Bhutan. Several constraints impede continuous monitoring of endangered species, such as the isolated and cryptic nature of the species and the remoteness of its habitat; to date, there are no long-term reference data or techniques implemented for continuous monitoring of this species.
2. In this study, we designed acoustic detection and habitat characterisation methods using long-duration recordings from three habitat areas in Bhutan. Acoustic indices were extracted and used to implement a species-specific call detector and to generate habitat soundscape representations. Using WBH calls annotated in month-long recordings from a known site, a novel indices-based detector was implemented and tested. A total of 960 hr of continuous audio recordings from three habitats in Bhutan were analysed.
3. We found that a species call detector implemented using a combination of acoustic indices (that includes measures of spectral and temporal entropy and different angles of spectral ridges) has a correct detection rate of 81%. Additionally, visual inspection of the species’ acoustic habitat using long-duration false-colour spectrograms enabled qualitative assessment of acoustic habitat structure and other dominant acoustic events.
4. This study proposes a combined approach of species acoustic detection and habitat soundscape analysis for holistic acoustic monitoring of endangered species. As a direct outcome of this work, we documented acoustic reference data on the critically endangered WBH from multiple habitat areas and have analysed its temporal vocalisation patterns across sites.

     

城市公园春季声景观与植被结构的关系

城市公园是城市生态系统的重要组成部分和城市生物多样性热点地区，具有丰富的声景观资源。由于声景观及声学方法具有信息量大，成本低，低侵入的特点，因此其研究和应用对生态系统健康及监测具有较高价值。声景观研究通过总结生物声的活动或多样性来衡量生物多样性。记录了北京20个城市公园的春季声景观，使用定量方法描述了声景观特征与变化；测试三种了已被证明与生物多样性相关并被广泛使用的声学指数（BIO、ADI、NDSI）与植被群落关系，完成了城市环境中声景观与环境关系的初步探究。研究结果表明：（1）声学指数能够有效表征城市公园声景观信息，具有显著的时间动态特性，能准确反映鸟类黎明合唱等重要生物生态活动；（2）声学强度指数也具有显著的时间动态变化和沿频率梯度的变化，不同的频率区间反映了不同声学群落的活动信息；（3）植被结构尤其是垂直结构对声景观起着重要作用，垂直异质性越大，声学多样性越高。发现支持声景观作为公园植被状况的度量，强调了其作为生物多样性和生态系统健康状况监测方法，用于城市管理和可持续发展的巨大潜力。     

Acoustic monitoring reveals diversity and surprising dynamics in tropical freshwater soundscapes

1. Freshwater systems are globally threatened and in need of enhanced monitoring and assessment. We applied soundscape recording and analysis—which presents an opportunity for long-term, high-resolution animal community monitoring and assessment—to a freshwater context to better understand the acoustic diversity and dynamics of these systems.
2. We recorded the aquatic soundscape of a Neotropical freshwater swamp in Costa Rica for 23 days in January and February 2015 during the dry season. We classified biological sound types in these recordings and developed measurements of richness and occupancy based on this classification. We also calculated six complementary acoustic indices to assess soundscape diversity and daily and longer-term soundscape dynamics, and we examined correlations between these acoustic indices and sound type metrics.
3. We found rich soundscapes in which biological sounds were almost always present, and we classified 18 sound types that we attribute to aquatic insects. These sound types showed distinct daily patterns and exhibited temporal and spectral acoustic niche partitioning. Sound type richness was most correlated with the number of peaks index (correlation = .36; p < .001), while sound type occupancy was most correlated with the Bioacoustic Index (correlation = .92; p < .001). In contrast to generally high levels of acoustic activity, there were brief (approximately 1 hr), unexpected quiet periods around dawn and dusk.
4. This study represents an early attempt to comprehensively describe tropical freshwater soundscapes in a systematic and quantitative manner. We demonstrate that sound type classification and the quantification of acoustic occupancy capture aspects of soundscape diversity and dynamics that are complementary to those assessed by acoustic indices. Our analyses reveal that the soundscapes of this tropical wetland were diverse and exhibited daily dynamics that differed from those found in other ecosystems.

     

Do soundscape indices predict landscape‐scale restoration outcomes? A comparative study of restored seabird island soundscapes

Measuring restoration outcomes is essential, but challenging and expensive, particularly on remote islands. Acoustic recording increases the scale of monitoring inexpensively; however, extracting biological information from large volumes of recordings remains challenging. Soundscape approaches, characterizing communities using acoustic indices, rapidly analyze large acoustic datasets and can be used to compare restoration sites against reference conditions. We tested this approach to measure nocturnal seabird recovery following invasive predator removal in the Aleutian Islands. We used recordings of nocturnal seabird soundscapes from six islands with varied histories of predators, from never invaded (one island) to 9–34 years post‐predator removal (four islands) and currently invaded (one island). We calculated 10 indices of acoustic intensity and complexity, and two pairwise indices of acoustic differences. Three indices reflected patterns of seabird recovery. Acoustic richness (measuring temporal entropy and amplitude) increased with time since predator removal and presence of historical predator refugia (r² = 0.44). These factors and moonlight accounted for 30% of variation in cumulative spectral difference from the reference island. Over 10% of acoustic richness and temporal entropy was explained by Leach's Storm‐petrel (Oceanodroma leucorhoa) calls. However, indices characterized the soundscape of rat‐invaded Kiska Island like a never invaded island, likely due to high abiotic noise and few seabird calls. Soundscape indices have potential to monitor outcomes of seabird restoration quickly and cheaply, if confounding factors are considered and controlled in experimental design. We suggest soundscape indices become part of the expanding acoustic monitoring toolbox to cost‐effectively measure restoration outcomes at scale and in remote areas.     

Spatio‐temporal scaling of biodiversity in acoustic tropical bird communities

Automated analysis of acoustic communities is a rapidly emerging approach for the characterization and monitoring of biodiversity. To evaluate its utility, we should verify that such ‘bioacoustics’ can accurately detect ecological signal in spatiotemporal acoustic data. Targeting the ‘Biological Dynamics of Forest Fragments Project’ sites in Brazil, we ask: What is the relative contribution of the spatial, temporal and habitat dimension to variation in bird acoustic communities in a previously fragmented tropical rainforest? Does the functional diversity of bird communities scale similarly to space and time as does species diversity, when both are recorded by bioacoustics means? Overall, is the imprint of landscape fragmentation 30 years ago still audible in the present‐day soundscape? We sampled forty‐four sites in secondary forest and 107 sites in old‐growth forest, resulting in 11 000 h of audio recordings. We detected 60 bird species with satisfactory precision and recovered a linear log–log relation between sampling time and species diversity. Sites in primary forest host more species than sites in secondary forest, but the difference decreased with sampling time, as the slope was slightly higher in secondary than primary forests. Functional diversity, as exposed by vocalizing birds, accumulates faster than does species diversity. The similarity among local communities decreases with distance in both time and space, but stability in time is remarkably high: two acoustic samples from the same site one year (or more) apart prove more similar than two samples taken at the same time but from sites situated just a few hundred meters apart. These findings suggest that habitat modification can be heard as a long‐lasting imprint on the soundscape of regenerating habitats and identify soundscape–area and soundscape–time relations as a promising tool for biodiversity research, applied biomonitoring and restoration ecology.