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Introduction: In production forests, management can have cascading effects on biodiversity and ecosystem services. Acoustic diversity reflects the diversity of vocalizing animals and has also considerable recreational value for human well-being, but the relationship between acoustic diversity and forest management remains largely unexplored Method: We recorded acoustic diversity on forest plots along a gradient of silvicultural management intensity (SMI) in three regions of Germany. We explored the diurnal and seasonal temporal dynamics in acoustic diversity index (ADI) from March to July using generalized additive mixed models (GAMMs). We further investigated the interrelation between acoustic diversity and silvicultural management intensity, forest structural diversity, as well as tree diversity, bird species richness and abundance using structural equation modeling (SEM). Results: Silvicultural management intensity had significant effects on the temporal dynamics of ADI in May and June from dawn till dusk, but variance explained by SMI was low. We confirmed our hypothesis that ADI was reduced by SMI due to its cascading effects on forest structural diversity and bird species richness and abundance. Discussion: Acoustic diversity indices can provide valuable insights into how forest management affects the acoustic activity of soniferous communities. We discuss how this can indicate both changes in species diversity as well as their vocal activity. We further address potential implications for forest management. [ABSTRACT FROM AUTHOR]

Given that ecosystems are composed of sounds created by geophysical events (e.g., wind, rain), animal behaviors (e.g., dawn songbird chorus), and human activities (e.g., tourism) that depend on seasonal climate conditions, the phenological patterns of a soundscape could be coupled with long-term weather station data as a complimentary ecological indicator of climate change. We tested whether the seasonality of the soundscape coincided with common weather variables used to monitor climate. We recorded ambient sounds hourly for five minutes (01 January-30 June) over three years (2019-2021) near a weather-station in a subarctic ecosystem in south-central Alaska. We quantified sonic information using the Acoustic Complexity Index (ACItf), coupled with weather data, and used machine learning (TreeNet) to identify sonic-climate relationships. We grouped ACItf according to time periods of prominent seasonal events (e.g., days with temperatures >0°C, no snow cover, green up, dawn biophony, and road-based tourism) and identified distinct sonic phenophases (sonophases) for groups with non-overlapping 95% confidence intervals. In general, sonic activity increased dramatically as winter transitioned to spring and summer. We identified two winter sonophases, a spring sonophase, and a summer sonophase, each coinciding with hours of daylight, temperature, precipitation, snow cover, and the prevalence of animal and human activities. We discuss how sonophases and weather data combined serve as a multidimensional, systems-based approach to understanding the ecological effects of climate change in subarctic environments. [ABSTRACT FROM AUTHOR]

According to the Sonotope Hypothesis, the heterogenous nature of the acoustically sensed, but not yet interpreted, environmental sounds (i.e., sonoscape) is created by the spatial and temporal conformation of sonic patches (sonotopes) as recently been described in a Mediterranean rural landscape. We investigated the Sonotope Hypothesis in a mountain beech forest of the Northern Apennines, Italy that is notoriously poor in soniferous species. Our aim was to test whether sonotopes were temporally distinct over seasonal and astronomical timeframes and spatially configured in relation to vegetation variables. We used the Acoustic Complexity Index (ACItf) to analyze the heterogeneity of sonic information gathered from an array of 11 sound recorders deployed within a lattice of eleven 4-ha hexagonal sample sites distributed throughout a 48-ha managed beech forest. We visualized and described the temporal patterns of ACItf between seasons (May-June and July-August 2021), across six astronomical periods (Night I, Morning Twilight, Morning, Afternoon, Evening Twilight, and Night II), and according to two aggregated frequency classes (<2000 and >2000 Hz). We introduced Spectral Sonic Signature (SSS) calculated from the sequence of ACItf values along frequency bins as a descriptor of the dynamic production of sounds across spatial and temporal scales. We calculated Mean Spectral Dissimilarity to compare SSS values across temporal periods and between sample sites. We identified sonotopes by grouping similar SSS for each sample site generated from cluster analyses and visualized their spatial arrangements. Frequencies <2000 Hz (mainly geophonies from wind and rain) were more prevalent than frequencies >2000 Hz (mainly biophonies from songbirds). Despite there being no strong relationship to vegetation variables and minimal biophony and anthropophony, distinct sonotopes still emerged for every astronomical and seasonal period. This suggests that the sonoscape expresses distinct spatial and temporal sonotope configurations associated with the temporal and spatial patterns of geophysical events that generate geophonies with minimal animal or anthropogenic occurrences. A new strategy based on the reintroduction of indigenous trees and shrubs in managed clearings should be considered for enhancing local biodiversity conservation along with ecoacoustic monitoring based on the Sonotope Hypothesis. [ABSTRACT FROM AUTHOR]

The fine-grained mosaic of natural and human-modified patches that characterizes the Mediterranean region has created a multifaceted system that is difficult to investigate using traditional ecological techniques. In this context, sounds have been found to be the optimum model to provide indirect and timely information about the state of ecosystems. The sonic nature of the environment (the soundscape) represents an important component of the landscape, and the new discipline of soundscape ecology has recently been shown to have appropriate tools for investigating the complexity of the environment. In the last decade, technological advances in the acoustic field have led researchers to carry out wide-scale and long-term ecological research using new and efficient tools, such as digital low cost sound recorders, and autonomous software and metrics. Particularly in the Mediterranean region, where land transformation occurs at a very rapid rate, soundscape analysis may represent an efficient tool with which to:1) track transformations in the community balance, 2) indicate the most acoustically complex parts (bioacoustic hotspots) of the land mosaic, 3) prevent environmental degradation, and 4) decide whether protection or restoration actions are most appropriate.

Byline: Almo Farina Complexity and landscape have been confronted using an epistemological approach. The complexity paradigm has been described using the Uncertainty Hypothesis (UH), the Inter-domain Hypothesis (IH), and the Connection Hypothesis (CH). The landscape ontogenesis theory that describes three main steps in landscape dynamic: novelties, opportunities and events, has been confronted with the complexity hypotheses using a probability perspective (PP), an energy perspective (EP) and a driver perspective (DP). Novelties have been found consistent with UH and PP, Events with IH and EP, and finally Opportunities are connected with CH and DP. This analysis confirms that landscape ontogenesis paradigm can be incorporated in the complexity theory, and that landscape ontogenesis represents a promising approach to investigate the complexity of meso-level systems like the landscape.

The biosemiotic complexity of acoustic communities in the primary forests of Ulu Temburong (Brunei, Borneo) and Yasunì (Ecuador, Amazon) was investigated with continuous 24-h recordings, using the acoustic signature and multiscale approach of ecoacoustic events and their emergent fractal dimensions. The 3D recordings used for the analysis were collected in undisturbed primary equatorial forests under the scope of the project, Fragments of Extinction, which produces 3D sound portraits with the highest definition possible using current technologies – a perfect dataset on which to perform a multiscale qualitative analysis. The ecoacoustic events (EEs) detected by a combination of the Acoustic Complexity Indices, ACIft, ACIft evenness, and ACItf evenness, and its fractal dimension were developed according to a biosemiotics approach in which the ecofield theory states that EE functions like a species-specific carrier of meaning. EEs, extracted according to 10 levels of temporal resolution, from 1 to 360 s, confirm the hypothesis that these acoustic communities have an internal complexity that responds to a fractal structure (fractal dimension D of Ulu Temburong D = 1.33 versus Yasunì D = 1.31). Yasunì was richer in EEs, with a higher coefficient of variation of hourly fractal dimension (Yasunì: D = 6.16 versus Ulu Temburong: D = 2.66). This methodology opens up promising new perspectives in the acoustic assessment of habitat quality and monitoring landscape modification. It also confirms the great potential of the biosemiotics approach in converting acoustic frequencies into ecoacoustic events through encoding procedures that mimic potential species-specific interpretations of the sonic environment. [ABSTRACT FROM AUTHOR]

Sounds - mechanical vibrations transmitted through an elastic medium - are generated by physical and biological agents and permeate every terrestrial and aquatic ecosystem on Earth. Soundscapes function as a container for different sources of semantic information that requires specific decoding processes which are interpreted by individual species, and there are various categories within the soundscapes arena. However, there is not an immediate connection between acoustic complexity and species richness, especially where soniferous species have a broad acoustic repertoire, as in temperate regions. [Extracted from the article]

The Ecoacoustic Event Detection and Identification (EEDI) system is a recent methodology to investigate structure and dynamic of soundscapes. In this study, EEDI has been re-engineered by adding to the Acoustic Complexity Index (ACI) calculated for each temporal step ( ACIf t ) and to its evenness ( ACIf t evenness ), the evenness of ACI calculated along each frequency bin ( ACIt f evenness ), and upgrading the ecoacoustic code (EC) from a two-digit to a three-digit code, thus increasing the analytical resolution of EEDI. Furthermore, a new metric, the Acoustic Information (AI) index, is introduced which is obtained by multiplying the value of each EC by the number of Recording Minutes (RM) in which every EC occurs. The EEDI was tested in four localities within a Mediterranean landscape using Soundscape Explorer [Terrestrial] digital recorders. Based on 273,360 RMs, 436 ECs were detected from a field recording system active from December 2015 to November 2016. The number of ECs and AI values increased in late winter and early spring, followed by a reduction in late spring and summer. A second increase was observed in early autumn. Based on bird phenology, non-significant differences in the number of ECs were found between the breeding (395 ECs) and non-breeding season (417 ECs). The sequence of the ECs during night time resulted in significant differences from the sequence of the ECs during daytime, but the number of RMs and of AI values of ECs exclusive of day or night time resulted negligible. Hourly abundance of ECs and the associated AI showed a similar sequence for all the localities, confirming a common daily pattern in soundscape organization. According to the way in which ECs are distributed along the 24 h, the first hundred more frequent ECs were aggregated into seven major patterns: some ECs have a dominant distribution around sunrise, whereas others prevail at midday or at night. EEDI provides a visual representation of each recording day (240 RMs) in an Euclidean space delimited by ACIf t (x), ACIf t evenness (y) and ACIt f evenness (z). An “asymptotical like” distribution that occurs during rain or wind events, and a “shower jet like” distribution that occurs when biophonies are dominant, are the two major patterns that were discovered. The ecoacoustic codes EC000, EC999, EC997, EC476, and EC271, have been utilized after their identification, to classify and analyze ecoacoustic events as an example of the capacity of EEDI. This holistic approach starting with detection of patterns delimited by the combination of ACI metrics associated with the AI, overcomes the usual procedure to first identify the sources and then determine the resulting patterns. The use of EEDI provides the potential to explore and to compare the characteristics of soundscapes with other environmental variables and represents an innovative and flexible ecological indicator. [ABSTRACT FROM AUTHOR]

Climate change is an important cause of the irreversible transformation of habitats, of the rapid extinction of species, and of the dramatic changes in entire communities, especially for tropical assemblages and for habitat- and range-restricted species, such as mountaintop and polar species. In particular, climate change effects several aspects of animal sounds (e.g., song amplitude and frequency, song post, and sound phenology). Animal sounds, which are life traits characterized by high plasticity, are able to cope with even modest variations of environmental fundamentals like vegetation cover, land mosaic structure, temperature, humidity, and pH (for aquatic medium). Moreover, the climatic effects on these biophonies can be observed earlier than change in vegetation patterns and visible landscape structures. Ecoacoustics, the discipline that investigates the role of sound on animal ecology from species to landscapes, offers robust models, such as acoustic adaptation, acoustic niche, acoustic active space, acoustic community, and acoustic phenology to investigate the effect of climate change on species, populations, communities, and landscapes. From an operational perspective, ecoacoustics procedures can be applied in different contexts, such as locations, weather, species, populations, behavior, physiology, and phenology. In addition, thematic priorities can be selected, such as latitudinal and altitudinal gradients, restricted habitats, stopover areas, extreme environments, weather conditions, short distance migrants, species at high vocal plasticity, sink-source status, active space, social attraction, physiological modifications, dawn and dusk choruses, sound from stressed plants, and time series analysis. The noninvasiveness of passive acoustic recording, the simultaneous collection of important data, such as community richness and diversity, immigration and extinction events, and singing dynamics as well as the availability of innovative noninvasive technologies operating over a long-term period, establish ecoacoustics as a new and important tool with which it is possible to analyze massive acoustic data sets and quickly predict and/or evaluate the effects of climate change on the environment. Moreover, passive recording is supported by cheap, user-friendly field sensors and robust data processing and may be part of the citizen science research agenda on climate change. [ABSTRACT FROM AUTHOR]

Ecoacoustic techniques using multiple acoustic sensors and two metrics of the acoustic community -- the acoustic complexity index (ACI) and the chorus ratio (CR) -- were successfully used to describe and characterize the morning acoustic activity of birds according to three equal temporal intervals during spring 2013: Dawn Chorus, Post Chorus 1, and Post Chorus 2.The metrics were applied across five Italian Mediterranean locations (Valenza, Madonna dei Colli, Monte Curto, Virolo, Croce di Tergagliana) that differed by land-cover typologies. Results from the ACI metrics showed a peak during the Dawn Chorus and a visible lull close to sunrise between Dawn Chorus and Post Chorus 1 .The lull was evident in all localities except Valenza, where singing activity was relatively constant across the successive morning intervals. Temperature and vegetation structure were confirmed as important factors associated with morning acoustic activities. Vegetation evenness and temperature across the season was negatively correlated with ACI, whereas CR was positively correlated with temperature and vegetation diversity. Of the 33 species of birds identified during the maximum dawn chorus activity. Blackcap, Blackbird, European Robin, and Great Tit were acoustically dominant and their activity was significantly higher before sunrise except for Blackcap, whose acoustic activity showed no significant differences across time intervals. The dawn chorus is one of the most conspicuous behaviours of birds, engendering much speculation but no definitive, univocal explanations. The ecoacoustic approach opens a new perspective for investigating this complex phenomenon. [ABSTRACT FROM AUTHOR]

Abstract: Herein we present one of the first attempts to couple the complexity of vegetation and topographic features with the sonic environment to understand the distribution of bird species and individuals in their habitat. To achieve this, the sonic features of a bird community were studied during the spring and early summer of 2011 in a Mediterranean maqui located on the western slope of a remote hanging valley that is dominated by Erica arborea, Quercus ilex and Arbutus unedo. Species composition, height, vertical foliage profile, canopy density and dispersion of vegetation were utilized as probable proxies for the sonic patterns. The acoustic activity of birds was collected through the use of a regular matrix of 20 audio recorders, spaced 25m apart, which were placed following the topographic isoclines. The sonic complexity of the soundscape was evaluated using the Acoustic Complexity Index (ACI), which is a recently developed metric. The PCA applied to the vegetation parameters revealed two principal distinguishing factors, which we were able to define as “vegetation density and structure” and “species segregation.” Moreover, the results show that, even in the case of sampling sites that are very close together, sonic patterns vary across the season, highlighting the great variability of the soundscape and confirming the adequacy of the sampling scale of 25m adopted in this study. The topographic features do not seem to be connected to the sonic environment. The main sonic complexity was found where the vegetation was taller and denser, especially where E. arborea was the dominant species. Although this proves that acoustic dynamics can be linked to vegetation structure, even on a small scale, a consistent element of sonic variability cannot be explained by vegetation patterns alone, and a soundtope hypothesis must be invoked. [Copyright &y& Elsevier]

The soundscape, which is defined as the entire acoustic environment of an area, is a relevant biosemiotic ingredient of environmental complexity. It is composed of geophonies, anthrophonies, and biophonies where, in temperate biomes, birds are the major producers of the latter. The soundscape is heterogeneous in terms of space and time, and is affected by landscape features such as vegetation cover (patch size and shape, length of edges, etc.). It also operates as a communication network in which intra- and inter-specific interactions create a complex, eavesdropping-broadcasting network, namely, the soundtope. This acoustic context provides public information for tracking resources like territory, mates, food, safety, and roosting sites and it can be considered a multifunctional eco-field. The Acoustic Complexity Index (ACI) is a new metric that is used to efficiently process the sound files that, when collected by sampling matrixes, return by interpolation the spatial distribution of a soundscape. High quality soundscapes are sought to guarantee the biosemiotic mechanisms among species, but polluted conditions (noisy acoustic environment of anthropogenic origin) degrade and mask biophonies, thus reducing communication efficiency, with severe consequences for both individual and collective fitness. Preserving high quality soundscapes is therefore an important conservation issue and a target to aim for if we are to assure animal and human wellbeing. [ABSTRACT FROM AUTHOR]

The Red-billed Leiothrix (Leiothrix lutea) is an invasive species which has recently been found to be locally abundant in eastern Liguria (Italy). The song production of this bird was recorded over the course of an entire year (2011) and evaluated using both aural information and applying innovative automatic processing metrics. Our findings revealed that the Red-billed Leiothrix has loud vocalizations that are heard for most of the year, including in July and August when other birds are silent. Its song production has been estimated to amount to 37% of the sounds uttered by the entire bird community. The next most vocal species are the European Robin (36%), the Common Blackbird (18%), the Subalpine Warbler (5%) and the Sardinian Warbler (1%). The Red-billed Leiothrix can be seen as a new acoustically dominant species and, consequently, a potential modifier of the soundscape patterns of the indigenous bird community. The modification of acoustic traits in the repertoire of both indigenous species and the Red-billed Leiothrix is to be expected according to a co-evolution hypothesis. [ABSTRACT FROM AUTHOR]