Soundscapes of urban parks: An innovative approach for ecosystem monitoring and adaptive management

Urban foresters are addressing the challenge of urban biodiversity loss through management plans in the context of rapid urbanization. Protecting the integrity of the urban ecosystem requires long-term monitoring and planning for resilience as well as effective management. The soundscape assessment has attracted attention in this field, but applying the soundscape assessment in urban ecological monitoring requires a protocol that links soundscapes to the impact of resource management on biodiversity over time. The effective processing and visualization of large-scale data also remains an important challenge. The aim of this study was to better understand the relationship between soundscape and physical environment, and examine the feasibility of this innovative soundscape approach in highly urbanized areas. Soundscape recordings were collected for 20 urban parks twice on 4 consecutive days in Spring. A total of 691,200 min of sound material were automatically obtained. In order to track the spatio-temporal patterns of a soundscape and determine its potential suitability for ecosystem monitoring, our study characterized soundscape information by adopting 4 widely used acoustic indices: acoustic diversity index (ADI), bioacoustic index (BIO), normalized difference vegetation index (NDSI), and power spectral density (PSD). Daily patterns of PSD have provided a potential connection between soundscapes and bird songs, and 1–2 kHz presented a similar pattern that was linked to human activity. Through further modeling, we tested the relationship of soundscapes to physical environment characteristics. The results showed the importance of habitat vegetation structure for acoustic diversity. More vertical heterogeneity, with an uneven canopy height or multilayered vegetation, was associated with more acoustic diversity. This suggests that clearing ground cover may have a significant negative impact on wildlife. Our results suggest that soundscape approaches provide a way to quickly synthesize large-scale recording data into meaningful patterns that can track changes in bird songs and ecosystem conditions. The proposed approach would enable regular assessment of urban parks and forests to inform adaptive planning and management strategies that can maintain or enhance biodiversity.     

What is soundscape ecology? An introduction and overview of an emerging new science

We summarize the foundational elements of a new area of research we call soundscape ecology. The study of sound in landscapes is based on an understanding of how sound, from various sources—biological, geophysical and anthropogenic—can be used to understand coupled natural-human dynamics across different spatial and temporal scales. Useful terms, such as soundscapes, biophony, geophony and anthrophony, are introduced and defined. The intellectual foundations of soundscape ecology are described—those of spatial ecology, bioacoustics, urban environmental acoustics and acoustic ecology. We argue that soundscape ecology differs from the humanities driven focus of acoustic ecology although soundscape ecology will likely need its rich vocabulary and conservation ethic. An integrative framework is presented that describes how climate, land transformations, biodiversity patterns, timing of life history events and human activities create the dynamic soundscape. We also summarize what is currently known about factors that control temporal soundscape dynamics and variability across spatial gradients. Several different phonic interactions (e.g., how anthrophony affects biophony) are also described. Soundscape ecology tools that will be needed are also discussed along with the several ways in which soundscapes need to be managed. This summary article helps frame the other more application-oriented papers that appear in this special issue.     

Spatial heterogeneity of ambient sound at the habitat type level: ecological implications and applications

While spatial heterogeneity is one the most studied ecological concepts, few or no studies have dealt with the subject of ambient sound heterogeneity from an ecological perspective. Similarly to ambient light conditions, which have been shown to play a significant role in ecological speciation, we investigated the existence of ambient sound heterogeneity and its possible relation to habitat structure and specifically to habitat types (as syntaxonomically defined ecological units). Considering that the structure and composition of animal communities are habitat type specific and that acoustic signals produced by animals may be shaped by the habitat’s vegetation structure, natural soundscapes are likely to be habitat specific. We recorded ambient sound in four forest and two grassland habitat types in Northern Greece. Using digital signal techniques and machine learning algorithms (self organizing maps, random forests), we concluded that ambient sound is not only spatially heterogeneous, but is also directly related to habitat type structure, pointing towards the existence of habitat type specific acoustic signatures. We provide evidence of the importance of soundscape heterogeneity and ambient sound signatures and a possible solution to the social cues versus vegetation characteristics debate in habitat selection theory.     

Urbanization increases the range,but not the depth,of forest edge influences on Pinus sylvestris bark pH

The influence of forest edge on Pinus sylvestris bark pH was evaluated in urban and suburban pine forests in Yekaterinburg (South Taiga subzone, Central Urals, Russia). The measurements was conducted in 18 transects (rows of 6–10 sample plots arranged in pairs along a 100–260 m line perpendicular to the forest boundary); 12 transects (110 plots) were located in the urban forest and 6 transects (58 plots) in the suburban forest. All the characteristics studied (degree of urbanization, distance from forest boundary, and type and age of boundary), were found to have a significant effect on the pH of P. sylvestris bark. Bark alkalinization increased on average by 0.2 to 0.5 pH units above background along a gradient from the forest interior to the forest edge. In urban forests, the edge influence was about twice greater (0.6–0.8 pH units) than in suburban forests (0.2–0.3 pH units), while the depth ranged between 70 and 160 m. Little variation in the depth of the edge influence observed due to transect characteristics, and no differences were noted due to degree of urbanization. The range of the edge influence was cumulative over the time that had elapsed since forest fragmentation and highway construction. The results show that urban airborne dust pollution affects southern taiga pine forests to a depth of about 100 to 150 meters from forest boundary. This circumstance is important to take into account when planning the locations of the borders of forests, roads, residential and social areas.     

Soundscape conservation

We argue that soundscapes possess both ecological and social value and that they should be considered natural resources worthy of management and conservation. In this paper we bring together diverse bodies of literature that identify the human and ecological benefits provided by soundscapes. Sense of place, cultural significance, interactions with landscape perceptions, and wildlife wellbeing are a few of the values ascribed to soundscapes. The values and benefits of soundscapes are motivation to advance soundscape conservation and management. Given that soundscape conservation is new, we present a summary of conservation principles that need to be considered in soundscape conservation planning. These include the need to set goals, identify targets, assess condition, identify and manage threats, and conduct monitoring of the soundscape. We also argue that soundscape conservation needs to consider the soundscape within the larger mosaic of the landscape that is occupied by humans—a perspective provided by landscape ecology. We describe several different kinds of soundscapes that need to be conserved, such as natural quiet, sensitive, threatened, and unique soundscapes, and the ways that conservation planning can protect these for the future.     

Linking ecological condition and the soundscape in fragmented Australian forests

Natural landscapes are increasingly subjected to anthropogenic pressure and fragmentation resulting in reduced ecological condition. In this study we examined the relationship between ecological condition and the soundscape in fragmented forest remnants of south-east Queensland, Australia. The region is noted for its high biodiversity value and increased pressure associated with habitat fragmentation and urbanisation. Ten sites defined by a distinct open eucalypt forest community dominated by spotted gum (Corymbia citriodora ssp. variegata) were stratified based on patch size and patch connectivity. Each site underwent a series of detailed vegetation condition and landscape assessments, together with bird surveys and acoustic analysis using relative soundscape power. Univariate and multivariate analyses indicated that the measurement of relative soundscape power reflects ecological condition and bird species richness, and is dependent on the extent of landscape fragmentation. We conclude that acoustic monitoring technologies provide a cost effective tool for measuring ecological condition, especially in conjunction with established field observations and recordings.     

Beyond noise mitigation: managing soundscapes as common-pool resources

The extent of noise and its impacts continues to grow globally indicating a different approach from regulating individual noise sources is needed. We pose the argument that soundscapes, or the acoustic environment, should be managed as a common-pool resource (CPR). Using CPR theory, we argue that soundscapes possess key features of CPRs: (1) multiple soundscape users, (2) difficulty of exclusion, and (3) subtractability and degradation. Using Ostrom’s Social-Ecological Systems (SES) framework, we describe the main elements of soundscapes to consider for their sustainable management. In order to assess noise issues and challenges in managing national park soundscapes, we conducted interviews with U.S. National Park Service managers at parks identified as having air tour overflight impacts. While most managers indicated that aircraft overflights posed the most serious impacts to park resources and visitor experiences, the park units also experienced several other types of noise impacts including traffic on park roads, park maintenance operations, and different types of motorized recreational vehicles. Addressing single sources of noise is necessary, as is the case with air tour overflights, but we argue that a more comprehensive approach is needed to protect park soundscapes. From this study several SES framework variables emerged that need to be addressed for sustainable management, such as the lack of clear soundscape boundaries, availability of acoustic monitoring and data, and the number and types of soundscape users. Based on CPR theory and using the SES framework, the challenges and a potential new approach for sustainable management are discussed.     

Audio-visual interaction and visitor characteristics affect perceived soundscape restorativeness: Case study in five parks in China

The capacity of urban parks to contribute to soundscape restorativeness, understood here as contributions to people’s recovery from attentional fatigue and reflection on life issues, is receiving increased interest in research and policy. However, scientific understanding of the influential mechanism of perceived soundscape restorativeness is still not clear. This paper aims to explore the effects of audio-visual interaction on perceived soundscape restorativeness (PSR) of urban parks, considering visitors of different social and demographic characteristics. The research design comprises a survey of 419 visitors to five urban parks in Fuzhou, China, general structure equation modeling, and multi-group model analysis. The results show a substantial dependence of visitors’ PSR values on respective perceptions of soundscape pleasantness and eventfulness, especially soundscape pleasantness. Visual landscape characteristics showed mediating effects on the influence of soundscape pleasantness and eventfulness on the perceived soundscape restorativeness (19.3 % and 28.3 % of the total effect, respectively). Age was the most influential social and demographic characteristic affecting the PSR, followed by gender, while occupation and educational background showed only limited effects. Future development of urban parks should strongly integrate soundscape design considerations to enhance positive PSR effects for visitors.     

Tree species-rich open oak woodlands within scattered urban landscapes promote biodiversity

It is becoming increasingly evident that cities are important places for biodiversity. Biodiverse urban forests are vital green areas within cities and have favorable impacts on the citizens, including their health. We focused on the effect of the urban forest environment on biodiversity in Prague, the capital of the Czech Republic. We used a multi-taxon approach with five taxa of different ecological demands: butterflies, bees and wasps, vascular plants, mosses, and lichens. We modeled their responses to the various urban forest attributes at four hierarchical levels – plot, permeability, forest, and landscape. Our results revealed that temporally continuous forests dominated by native oaks with open canopies, a high number of admixed and interspersed tree species and shrubs, together with scattered trees in the surrounding landscape, were optimal biodiverse forest environments. The most influential parameter that positively influenced bees and wasps, plants, and lichens at the plot level was canopy openness. We found that the permeability was suitable mainly on 20 m surroundings and increasing coverage of native oaks and tree species richness were the most important parameters. Continuity was the only found parameter that influenced mosses at the forest level. Scattered tree vegetation was the most important landscape parameter and positively drove the species richness of bees and wasps. Forest management methods can relatively easily solve the improvement of the scattered light gap structure within urban forests. Applying traditional forest management (pasture management, controlled burning and/or coppicing) is also an option but requires sensitive communication with the public. The canopy cover has been used as an indicator of urban forest health conditions, now indicating that artificial disturbances could be important issues for urban forest management and planning in the future. Therefore, active forest management is an essential method for biodiversity maintenance. We conclude that urban forests have a high potential for increasing native biodiversity. The response of the studied groups in urban forests was complementary. The resulting biodiverse stages of urban forests are akin to the established idea of the open temperate deciduous woodlands.     

Temporal and spatial variation of a winter soundscape in south-central Alaska

Context

Winter soundscapes are likely different from soundscapes in other seasons considering wildlife vocalizations (biophony) decrease, wind events (geophony) increase, and winter vehicle noise (technophony) occurs. The temporal variation and spatial relationships of soundscape components to the landscape in winter have not been quantified and described until now.

Objectives

Our objectives were to determine the temporal and spatial variation and acoustic–environmental relationships of a winter soundscape in south-central Alaska.

Methods

We recorded ambient sounds at 62 locations throughout Kenai National Wildlife Refuge (December 2011–April 2012). We calculated the normalized power spectral density in 59,597 recordings and used machine learning to determine acoustic–environmental relationships and produce spatial models of soundscape components.

Results

Geophony was the most prevalent component (84 %) followed by technophony (15 %), and biophony (1 %). Geophony occurred primarily at night, varied little by month, and was strongly associated with lakes. Technophony and biophony had similar temporal variation, peaking in April. Technophony occurred closer to urban areas and at locations with high snowmobile activity. Biophony occurred closer to rivers and was inversely related to snowmobile activity. Over 75 % of sample sites had >1 recordings of airplane or snowmobile noise, mainly in remote areas.

Conclusions

The soundscape displayed distinct patterns across 24-h and monthly timeframes. These patterns were strongly associated with land cover variables which demonstrate discrete acoustic–environmental relationships exhibiting distinct spatial patterns in the landscape. Despite the predominance of geophony, the presence of technophony in this winter soundscape may have significant negative effects to wildlife and wilderness quality.

     

The effects of trees on air pollutant levels in peri-urban near-road environments

It is often stated that plants remove air pollutants from the urban atmosphere with their large leaf area, thus providing benefits − i.e. ecosystem services − for citizens. However, empirical evidence showing that local-scale air quality is uniformly improved by urban forests is scarce. We studied the influence of conifer-dominated peri-urban forests on the springtime levels of NO₂ and particle pollution at different distances from roads, using passive samplers and high time resolution particle counters in a northern climate in Finland. Passive samplers provided average values over a one month period, while active particle counters provided real time measurements of air pollution to mimic human inhalation frequency. NO₂ concentrations were slightly higher in forests than in adjacent open areas, while passive particle measurements showed the opposite trend. Active particle monitoring campaigns showed no systematic forest effect for PM2.5, but larger particles were reduced in the forest, corroborating the passive sampling result.Attenuation rates of the mean values of the studied pollutants did not differ between the forest and open habitats. However, high time resolution particle data revealed a distance effect that was apparent only in the forest transect: peak events at the forest edge were higher, while peaks furthest from the road were lower compared to the open transect. Furthermore, the magnitude of PM2.5 peak events was distinctly higher at forest edge than equivalent distance in the open area.Vegetation characteristics, such as canopy cover and tree density, did not explain differences in pollutant levels in majority of cases. Our results imply that evergreen-dominated forests near roads can slightly worsen local air quality regarding NO₂ and PM2.5 in northern climates, but that coarser particle pollution can be reduced by such forest vegetation. It seems that the potential of roadside vegetation to mitigate air pollution is largely determined by the vegetation effects on airflow.     

Spatial variations of plant species diversity in urban soil seed banks in Beijing,China: Implications for plant regeneration and succession

The near-to-nature urban forestry concept and practices are widely recognized for urban greening, urban ecosystem restoration, urban greenspace management for biodiversity conservation and ecosystem services provision. However, the regeneration and succession of urban vegetation are rarely studied due to the complex settings of the urban environment. To this end, we conducted a large-scale field investigation in the metropolitan area of Beijing, China to explore the spatial variations in plant species composition and diversity in soil seed banks, and their similarity to the aboveground vegetation to assess the potential of urban plant regeneration. Overall, 657 vegetation and soil sampling plots from 219 grids, measuring 2 km × 2 km each, were investigated within two perpendicular 10 km wide transects running across the urban center in north-south and east-west directions within the 6th Ring Road of the city. We recorded a total of 102 plant species in soil seed banks, including 13 tree species, 10 shrub species, and 79 herb species. We found that the soil seed bank species diversity and its similarity to that of the aboveground vegetation communities decreased significantly with the urbanization intensity. Higher urbanization intensity is typically associated with increased human management and a reduction in Greenspace Area (GSA). Soil seed bank species richness increased significantly when GSA exceeded 45 % and the similarity of species composition and diversity between soil seed banks and aboveground vegetation communities was the highest in forest parks. This suggests that habitats under forest park management are more conducive to plant regeneration. Soil seed bank species diversity first increased and then decreased significantly with increased distance to the city center, whereas the species similarity between the soil seed banks and the aboveground vegetation communities showed little change with the ring roads going out. The results of this study have important implications for further understanding the potential for urban vegetation regeneration and sustainability, which have significant implications for urban biodiversity conservation and restoration.     

The utility of ancient forest indicator species in urban environments: A case study from Poznań, Poland

We aimed to assess the impact of land-use structure on AFIS occurrence and evaluation of these bioindicators in urban conditions. We compiled data about forest continuity based on archival maps and forest management plans; floristic records of 79 AFIS occurrences were collected within a 1 × 1 km grid and land-use form structure in Poznań (W Poland). We tested fidelity of AFIS using χ² tests and effects of land-use structure using random forest models. We also checked spatial autocorrelation and its impact on AFIS distribution patterns within old and recent forests, using spatially explicit generalized linear models. We found a strong relationship between AFIS number per grid square and fraction of forests and waters in land-use structure. Relationships between AFIS distribution and land-use shows that AFIS are a good proxy describing human impact or an urbanity gradient. AFIS number per grid square shows small, but significant positive spatial autocorrelation, which suggests possibilities of migration into new forests. AFIS, treated as a bioindicative group of species, may be a useful indicator of landscape and land-use structure transformation in urban environments. Occurrence of many AFIS that are endangered at the city scale indicates the need for conservation of old forests in urban areas, to preserve biodiversity in urban environments. Thus, AFIS may act as indicators of old forests with high conservation value in cities, which need special protection.     

Roads limit of seed dispersal and seedling recruitment of Quercus chenii in an urban hillside forest

Paved roads in urban forests cause forest fragmentation and thus reduce animal populations, threaten dispersal and recruitment of animal-dispersed plants. Here, we tracked animal-mediated seed dispersal of Quercus chenii in the urban forest centre and near roadsides to test the effect of paved roads on seed dispersal and recruitment. We conducted experiments in a forest patch in urban areas of Wuhan, China. The forest was dominated by the focal tree species and separated by paved roads. Only two potential seed dispersal animals, one rodent (Niviventer confucianus) and one jay (Garrulus glandarius) were observed in this stand. Seeds were removed farther but not as fast in the forest centre compared to roadsides, while no differences of seed fate, dispersal direction, and seedling establishment were detected between the forest centre and roadsides, indicating the thick vegetation along roadsides provided feeding shelters for small animals. However, when compared with primary forests containing more seed dispersers, seed removal rate in this urban forest fragment was much slower in both forest centre and roadside. Furthermore, due to road barriers, seeds were seldom moved across the paved road and remained in the fragmented stand, reflecting a limited function of seed dispersers. These results suggested paved roads isolated forests into small “islands” and weakened the ecological function of seed dispersers by impeding long distance seed dispersal. Reintroducing dispersers and building wildlife corridors would be impactful ways to restore urban forest patches.     

A systematic review of the relationship between urban forest quality and socioeconomic status or race

The quantity of urban forests in cities is critical for biodiversity conservation and human health, and is known to be distributed unequally. Increasingly, the quality of urban forests are also being recognised as shaping the benefits they provide. Previous studies and reviews have demonstrated that the quality of urban green spaces is associated with patterns of inequality as measured by socio-economic status and race (in the U.S). This study extends this body of knowledge to urban forests by systematically reviewing the urban forest literature (that explicitly study the urban forest) exploring the relationship between urban forest quality and both socio-economic status and race. Two academic databases (SCOPUS and Web of Science) were systematically searched. A total of 2012 papers were screened and 21 articles were included in this study. Almost all studies (20/21) found evidence of inequality, with at least one significant association between measures of urban forest quality and socio-economic status or race. However, 6 studies found contrasting patterns, with lower socioeconomic status areas having higher urban forest quality. There was variation in the type of ‘urban forest’ studied, and variation in the ways both urban forest quality and socio-economic status were measured, making inter-study comparisons difficult. Interestingly, the literature was geographically diverse, and future research could continue to focus on countries in Africa, South America and Asia with diverse needs for and uses of urban forests. In conclusion, this review finds evidence for inequity in the distribution of urban forest quality. Future research that more clearly describes the urban forests being studied and that explores sociocultural variation in perceived quality would allow better generalisation and understanding of forest quality patterns.     

Preferences of urban dwellers on urban forest recreational services in South Korea

This paper aims to investigate the preferences of urban dwellers for various attributes of urban forests, with an emphasis on forest recreational services. A choice experiment was conducted using face-to-face interviews with 823 urban dwellers in 2010. Urban forest attributes such as trails, slope, biodiversity, environmental education programs and entrance fees were found to influence Korean citizens’ preferences regarding urban forests. Among the six urban forest attributes, biodiversity was the most influential among Korean urban dwellers in their choice of urban forest recreation. Three latent groups with relatively homogeneous preferences over various urban forest attributes were identified. Residential area, family composition and the purpose of their visit determined group membership. It was notable that the preferences of urban forest recreationists differ from the general preferences of visitors to forests located in remote areas. Urban forest planning and management should consider the attributes of urban forests and the preferences of citizens visiting urban forests to improve urban dwellers’ welfare.     

Measuring and interpreting the temporal variability in the soundscape at four places in Sequoia National Park

The soundscape was recorded in four selected places in Sequoia National Park CA, to quantify and assess the diurnal and seasonal character of the park’s soundscape. The recording sites were selected to represent a combination of elevation and vegetation diversity. Hour-long sound recordings were made by four individuals at each place during fall, spring, summer and winter at dawn, midday, dusk, and midnight with identical recording instrumentation. The recordings of the soundscape were made in an old growth forest (Crescent Meadow), in a foothill oak savanna (Sycamore Spring), in an upland savanna chaparral (Shepherd Saddle) and in a foothill riparian location adjacent to the Kiawah River (Buckeye Flat). Sound recordings were analyzed using a normalized Power Spectral Density (PSD) algorithm and partitioned into 1 kHz intervals based on 12 subsamples from each of the 64 h-long sound recordings. Biological signals (biophony) were based on the highest PSD value within the range of 2–8 kHz. A multilevel analysis (MLA) was used to examine temporal patterns of biophony at four locations in Sequoia National Park. Unsupervised Landsat Thematic Mapper Satellite Imagery identified 25 vegetation regimes in Sequoia National Park. Satellite signatures of the habitat where recordings were made were extracted from the imagery to scale to the region.     

URban Biotopes of Aotearoa New Zealand (URBANZ) II: Floristics, biodiversity and conservation values of urban residential and public woodlands, Christchurch

Urban forests are increasingly valued for multiple benefits such as amenity, cultural values, native biodiversity, ecosystem services, and carbon sequestration. Urban biodiversity in particular, is the new focus although global homogenisation is undermining regional differentiation. In the northern hemisphere (e.g., Canada and USA) and in the southern hemisphere, particularly in countries like South Africa, Australia, South America and New Zealand, local biodiversity is further impacted by historical colonisation from Europe. After several centuries, urban forests are now composed of synthetic and spontaneous mixtures of native species, and exotic species from around the temperate world (e.g., Europe, North and South America, South Africa, Asia). As far as we are aware no-one has carried out in-depth study of these synthetic forests in any Southern Hemisphere city. Here we describe the composition, structure, and biodiversity conservation imperatives of urban temperate forests at 90 random locations in Christchurch city, New Zealand.We document considerable plant diversity; the total number of species encountered in the 253 sampled urban forest patches was 486. Despite this incredibly variable data set, our ability to explain variation in species richness was surprisingly good and clearly indicates that total species richness was higher in larger patches with greater litter and vegetation cover, and taller canopy height. Species richness was also higher in patches surrounded by higher population densities and closer to very large native forest patches. Native species richness was higher in patches with higher soil pH, lower canopy height, and greater litter cover and in patches closer to very large native forest patches indicating dispersal out of native areas and into gardens. Eight distinct forest communities were identified by Two-Way INdicator SPecies ANalysis (TWINSPAN) using the occurrence of 241 species that occurred in more than two out of all 253 forest patches.Christchurch urban forest canopies were dominated by exotic tree species in parklands and in street tree plantings (linear parkland). Native tree and shrub species were not as common in public spaces but their overall density high in residential gardens. There was some explanatory power in our data, since less deprivation resulted in greater diversity and density, and more native species, which in turn is associated with private ownership. We hypothesise that a number of other factors, which were not well reflected in our measured environmental variables, are responsible for much of the remaining variation in the plant community structure, e.g., advertising, peoples choice. For a more sustainable asset base of native trees in New Zealand cities we need more, longer-lived native species, in large public spaces, including a greater proportion of species that bear fruit and nectar suitable for native wildlife. We may then achieve cities with ecological integrity that present multiple historical dimensions, and sequester carbon in legible landscapes.     

Spatial-temporal change analysis of plant soundscapes and their design methods

The aim of the study was to describe the soundscape elements, spatial-temporal changes and preferences in plant soundscape using quantitative measures, in order to recommend soundscape design methods. Both acoustic measurements and subjective evaluations of the soundscapes were conducted at various locations in Jinan Forest Park using 14 groups of plant spaces within the park. Our analysis investigated soundscape elements categorized as nature sounds, human activity sounds, and mechanical sounds. The soundscapes varied with time of day and season and were influenced by the surrounding environment and human behavior. Soundscape element preferences were correlated with a visitor’s age and visitation frequency, with nature sounds receiving the highest preference scores. Closed nature spaces had lower sound levels and received the highest preference by visitors. The results were further analyzed according to five soundscape methods to improve visitor experience: sound-masking, sound-borrowing, sound-reinforcement, sound-contrasting, and sound-expectation, that are also consistent with Chinese classical garden design.     

Comparing the carbon sequestration capacity of temperate deciduous forests between urban and rural landscapes in central Japan

Urbanisation is increasing tremendously in some parts of the world. Consequently, many rural forests may become depleted, although many opportunities exist for urban forests to increase. However, few studies have quantified the carbon (C) sequestration capacities of urban and rural forests in specific climatic zones. The present study compared carbon sequestration in two temperate deciduous forests located in Nagoya and Toyota, central Japan. The Nagoya University forest represented an urban forest, and a site in Toyota represented a rural forest. The urban forest at Nagoya University had comparatively smaller areas of green space and larger areas of buildings and roads. Land uses for building and road, which are typical of urban areas, result in smaller diurnal temperature ranges but higher air temperature, vapour pressure deficit, and atmospheric carbon dioxide (CO₂) concentration. The urban forest in this study exhibited higher gross ecosystem exchange (GEE), especially in the active growing season from May to September, suggesting the possible effect of CO₂ fertilisation. However, higher air temperatures caused comparatively smaller net ecosystem exchange (NEE) because of higher ecosystem respiration (RE). Although both forests functioned as CO₂ sinks at annual time scales, the rural Toyota forest site (5.43 t C ha^–1 yr^–1) had 36% higher net ecosystem production (NEP=–NEE; the negative sign indicates uptake by the forest ecosystem from the atmosphere) than that at the urban forest. The higher normalised respiration (i.e., RE/GPP ratio; GPP=–GEE where GPP represents gross primary production) at the Nagoya University forest might be attributable to factors associated with the degree of urbanisation. Thus, in temperate forests, factors associated with urbanisation may reduce the atmospheric carbon sink function by accelerating respiration. This is an issue of global interest, as many countries are experiencing rapid urbanisation.