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1.
Private domestic gardens are known to constitute a considerable proportion of “green space” in urban areas and are therefore of potential significance for maintaining biodiversity and ecosystem service provision in such areas. However, little is known about the actual size and nature of this resource. This study provides the first detailed audit and comparison of the size and structure of the domestic garden resource across different cities in the U.K. (Edinburgh, Belfast, Leicester, Oxford and Cardiff). The urban area of each city covered by domestic gardens ranged from 21.8% to 26.8% and was positively correlated with variation in human population density and housing density. In a random sample of at least 500 houses in each city, 99% had associated gardens, the mean areas of which ranged from 155.4 m2 to 253.0 m2 and were closely associated with housing type (terraced, semi-detached or detached houses). Relatively small gardens (< 400 m2) contributed disproportionately to the total garden area of each city, being more numerous than larger gardens. There was no clear relationship between garden area and distance to the edge of any of the cities. These and other results are discussed in terms of the potential role of urban gardens as wildlife habitats and the implications for housing policy.  相似文献   

2.
While we know that urban vegetation is often distributed unequally, most studies have been undertaken in cities with relatively high levels of income inequality, using a single measure of distribution (usually tree cover) and in a single land use. This study explores predictors of both tree cover and species richness in gardens, streetscapes and parks in Ballarat, Australia. Spatial regression models found that education level was a more important predictor of tree cover than household income across all land uses in Ballarat which can be explained by some people with high incomes relative to education level choosing to live in new residential developments with disproportionately low levels of tree cover. Inequality in tree cover was greater in streetscapes than in residential gardens, suggesting that ‘top down’ political factors are more important than individual behaviours in determining tree cover in Ballarat. In contrast, physical rather than socioeconomic factors were better predictors of species richness across all land uses, highlighting that different measures of vegetation distribution are not necessarily correlated.  相似文献   

3.
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.  相似文献   

4.
5.
There is increasing focus on designing liveable cities that promote walking. However, urban walking routes can expose people to adverse environmental conditions that reduce health, well-being and biodiversity. Our primary objective is to assess how urban form is associated with environmental quality, including biodiversity, for people moving through urban spaces. We assess a range of environmental conditions that influence human health and biodiversity (temperature, noise and particulate pollution) and biodiversity of three taxa (trees, butterflies and birds) along 700 m public walking routes embedded in 500 m x 500 m grid cells across three UK towns. Cells are selected using random stratification across an urbanisation intensity gradient. Walking routes in more built-up areas were noisier and hotter; noise levels further increased in areas with more industrial land-use and large roads. There was no evidence of vegetation mitigating noise or temperature, but there was some evidence that increased vegetation cover mitigated small particulate pollution. Walking routes in more built-up environments had lower butterfly, bird and native tree species richness, and reduced butterfly abundance. Large roads were associated with reduced bird species richness and increased noise was associated with reduced bird abundance. Most specific measures of vegetation in the surrounding matrix (median patch size, structural complexity at 1.5 m resolution) were not detectably associated with biodiversity along walking routes, indicating minimal beneficial spill-over. Increased garden cover in the surrounding matrix was associated with less abundant and less species-rich butterfly communities. Our results highlight considerable heterogeneity in the environmental quality of urban walking routes and pedestrians’ potential to experience biodiversity along these routes, driven by reduced quality in areas with more built cover. A greater focus is needed on mitigating adverse effects of specific features of the built environment (roads, industrial areas, noise) surrounding walking routes to enhance the co-benefits of more biodiversity and healthier conditions for pedestrians.  相似文献   

6.
Sky gardens have been actively studied and installed in different cities. Their development potential in compact developing cities has received little attention. Using remote sensing and GIS techniques, this study evaluates the vegetation configuration and development potential of sky gardens in urban Hong Kong, their underlying location, land use and building factors, and future planning and implementation concerns. Existing sky garden area is limited with sparse vegetation cover and low biomass. Existing podium gardens exceed roof gardens by about nine times. District development age has little effect on existing and potential sky gardens. Old towns have higher potential roof and podium gardens than new towns in most land uses. The effect of land use on potential sky gardens varies greatly by districts. Buildings with 10–20 floors have higher potential roof gardens in most districts. Building area is the main determinant of potential roof garden, and population density of potential podium gardens. Three scenarios of realization, namely minimum (20%), medium (50%) and maximum (80%), are adopted to project sky garden provision in individual districts. The projection extends to the contribution of new sky gardens to urban greening in terms of green cover and greening rate in districts. The challenges include susceptibility to typhoon damage in high-rise exposed sites, aggressive weed invasion, lack of roof-slab loading data in old buildings, and poor building maintenance. The opportunities include affordability of the new technology, enabling government policy, and establishment of scientific and research foundation in the local context. The development strategy could aim squarely at stringent technical standards and contractor skill requirement, and programme prioritization based on research findings. The study provides useful hints, approaches and recommendations for a systematic sky-garden action plan in Hong Kong and other similar compact cities.  相似文献   

7.
Mature trees provide a range of ecosystem services in urban landscapes, represent important wildlife habitat, and impact positively on human wellbeing. However, mature trees are perceived as a risk to people and infrastructure and occupy land suitable for development. Trees are slow to reach ecological maturity and thus difficult to replace when removed. In this study, we: (a) quantified native canopy cover retained during residential development using aerial imagery; (b) identified where native trees are/are not retained within residential developments with a focus on mature trees; and (c) evaluated the effectiveness of current legal mechanisms for protecting native trees during residential development. Native canopy cover was reduced by 49% during residential development. Mature trees had the highest probability of retention within residential developments if they occurred within intact remnant vegetation. A lower probability of retention for mature trees was observed in urban green space, and almost no mature trees were retained in other areas within residential developments, such as residential blocks and road verges. Mature trees had greater probability of retention where the jurisdiction offered some legislative protection. The loss of mature trees during residential development could be reduced with a greater focus on avoiding the removal of existing trees during the planning stage rather than offsetting the impacts elsewhere; and by designing green space within residential developments to ensure adequate separation between mature trees and people and infrastructure.  相似文献   

8.
Domestic gardens constitute important refuges for biodiversity. However, their typical small size mismatches with the larger scales at which species procure resources from urban areas. Consequently, they lack the capacity to enhance biodiversity at these scales. This could be addressed by aggregating garden resources (e.g. vegetation) and increasing garden connectivity. Specifically, this could involve neighbouring householders removing brick walls and fences that segregate gardens and collectively planting vegetation across garden boundaries. Nevertheless, insufficient research has explored 1) how hard surfacing gardens influences native/non-native vegetation presence, which could influence this action’s effectiveness 2) the number of householders willing to undertake such action 3) reasons for unwillingness and how this could be resolved. These research gaps were addressed using an online householder questionnaire distributed weekly to the UK ‘followers’ of four Facebook pages from January to December 2014. From a total of 276 respondents, 220 (84 %) had gardens with hard surface and this had a significant negative association with native vegetation presence. Only 7 (3%) presently collectively planted vegetation, but 152 (58 %) expressed future willingness. Desires to retain garden control and privacy predominantly underpinned unwillingness. In order to increase the effectiveness and prevalence of collectively planted vegetation, more stringent planning policy is required to restrict hard surfaced gardens. Moreover, desires for garden control and privacy need to be accommodated. This could be principally achieved by 1) communicating that little control would be lost as a result of this action 2) segregating gardens with hedges, which benefit biodiversity and simultaneously provide privacy.  相似文献   

9.
Fine-scale vegetation patches (<5 m in width) are critically important in many landscapes because they function to obstruct surface flows of water and wind. These obstructions increase the infiltration of runoff and the capture of nutrients in runoff sediments and in wind-blown soil and litter. The importance of redistribution of runoff into runon patches from spaces between patches (fetches) is likely to be greater in drier than in wetter environments. In this paper we examine the hypothesis that the ratio of fetch to patch decreases as rainfall increases, and that this trend will be most evident on intermediate-textured soils because these soils are more prone to runoff. We measured fine-scale patches on 38 sites with sand, loam or clay soils. Sites were located along a 1000-mm rainfall gradient in the savannas of northern Australia. The width and intercept length of patches and the fetch between patches was measuring along line transects of 100–120 m oriented down slope. We found that the ratio of fetch to patch area did not decrease with decreasing rainfall, but increased on both sand and loam soils. This result was because with increasing rainfall mean spacing between patches disproportionally increased while mean patch size and cover declined. The cover of patches was negatively correlated with tree canopy cover, which significantly increased with rainfall. This negative correlation suggests that in higher rainfall savannas the size and spacing of ground-layer patches is controlled by the tree layer, and that as rainfall decreases this control decreases and runoff-runon processes increasingly structure the landscape. For savannas on clay soils these trends were not significant except that on the highest rainfall sites the cover of ground-layer patches was nearly 100% while trees were absent.  相似文献   

10.
Declining urban tree canopy cover in the United States underscores the importance of elucidating factors that influence the distribution of urban trees. This is particularly relevant as most urban trees are located on private property while their canopies maintain ecosystem services that constitute public goods. Thus, municipalities establish institutions in the form of canopy cover goals and various policies to incentivize private actions to meet those goals. However, urban land use, as governed by municipal zoning policies, plays a role in the abundance, distribution, and potential future location of urban trees independent of policies meant specifically to manage canopy. For instance, previous research finds that lands zoned for residential and park development have the highest canopy cover relative to other land uses. Yet, little research has explored whether this conclusion holds across scales of analysis and how it might influence our understanding of potential canopy cover and relative canopy cover. Thus, we ask, does the nature of the relationship between zoning and canopy cover change between aggregated and disaggregated zoning scales and how might this knowledge improve the sustainability of urban forest management? To answer this question, we classified high resolution National Agriculture Imagery Program (NAIP) images of Bloomington, Indiana land cover and compared existing, potential and relative canopy cover across aggregated and disaggregated zones. Results demonstrate an important exception to the oft-cited theory that residential lands have higher canopy cover, a conclusion that our data supports only at the scale of an aggregated interpretation of zoning. At a disaggregated scale, residential high density zones are significantly different than all other residential zones and more akin to commercial zones in terms of all canopy metrics. For urban forest managers and urban planners, this suggests the relevance of fine-scale variation in land-use policies and related canopy cover policies.  相似文献   

11.
Environmental weeds have ecologic and economic costs, harming native vegetation and costing the agricultural industry billions of dollars annually. Many environmental weeds are garden escapees; thus, what the public chooses to plant in their gardens is important. This research investigated the environmental attitudes (related to environmental weeds) of residents in the City of Knox, Melbourne, Australia and whether illustrative education (comic) could influence participants to choose native plants in the future. Two identical surveys (total 2000) were sent to residents chosen randomly within the City of Knox; half of the surveys had a comic added that demonstrated the pathway garden plants could take to invade bushland. Responses (n = 181) indicated that the majority of respondents hold pro-environmental attitudes in regards to gardens and environmental weeds, with most agreeing that residential gardens are important for urban areas and that gardeners have a responsibility to the environment when it comes to the use of plants that may be invasive. The results showed that significantly more participants that received the comic indicated they would choose mostly natives in the future than did those who did not receive the comic.  相似文献   

12.
There is a growing body of literature examining the multifaceted benefits of community gardens for environmental and social wellbeing. While there are studies examining the increase of grassroots urban gardening initiatives in low income and vulnerable communities, there remains a need for research that explores the lived experiences of individuals in social housing communities with urban nature and community gardens. Individuals living in urban social housing may experience inequalities in access to green infrastructure both within their housing estates as well as the surrounding community. For the past two decades, the Community Greening program at the Royal Botanic Garden Sydney, Australia, has implemented outreach initiatives to support the development and maintenance of community gardens in social housing communities in New South Wales. This article presents the findings from a study conducted with participants at six new community gardens built in social housing communities, focusing specifically on focus group interviews with residents and staff questionnaires to examine the perceived impact of the Community Greening program. The participants’ narratives highlight program outcomes across the key themes of community gardens as sites for knowledge generation and connection to nature, sense of community, and improving residents' sense of pride and public perceptions of public housing. The findings suggest that community gardens enhance green infrastructure in social housing estates and their broader urban locales by improving access to green space and promoting place-making in social housing contexts. We conclude with a discussion of the recommendations and lessons learned that may help to inform future policies and practices when setting priorities that promote social and environmental sustainability in social housing.  相似文献   

13.
Urban tree canopy yields numerous environmental and social benefits. This study investigates whether the marginal contribution of tree canopy cover to home values depends on certain characteristics of a property and its location. We address this using a hedonic property analysis with data from Baltimore, Maryland. Both Ordinary Least Square and Spatial Lag models were conducted, all including interaction terms between tree canopy cover and various site factors. Our results indicated that, on average, the amount of tree canopy in the 100–400 zone around a single-family property is positively associated with home price. We also find that the marginal impact of canopy on property price increases for properties that are larger in lot size and closer to downtown Baltimore. Model results were mixed in terms of the interactive effects of crime and proximity to major roadway with tree canopy. We suggest that the benefits that tree canopy provides in the form of added privacy, reduced urban heat, noise and pollution may influence these price increases. These findings may signal concerns about the potential for urban greening to contribute to gentrification. In a competitive housing market, those with the capacity to afford to pay more for urban tree canopy and the benefits it provides such as a cooler downtown environment, privacy on larger lots, or reduced noise and pollution from a major roadway may price out those who are unable to pay this urban tree canopy premium. There is, therefore, the potential for unequal increases in home equity across neighborhoods following tree planting and urban greening in Baltimore.  相似文献   

14.
According to the national policy, overall forest and agroforestry cover in Rwanda is to increase up to 30% land cover by 2020. On the other hand, demographic data reveal that Rwanda's urban areas are among the fastest-growing on the continent. Unfortunately, there is only little information of the effects of such a rapid urbanization on tree cover and green space structure, knowing that data on urban plant assemblages in the country are rather rare. The paper discusses developments in Kigali's green spaces with regard to its rapid rate of expansion. An integrated approach of research, combining results from interview sessions, desk-based investigations, walk-over and vegetation surveys, and photogrammetric analyses of remotely acquired imagery was applied. The findings suggest that the city green space network consists of plant assemblages largely dominated by alien species (75%). Tree cover fraction averaged at around 10–35%. No significant difference was observed between field-drawn and photogrammetric-based fraction of tree cover estimates; making the later a quick but cheap tool for rapid tree cover evaluation. Cultivated forests, urban woodlots and domestic garden tree stands are far the most dominant types of green spaces in terms of coverage of city surface area. Street tree communities and institutional gardens appear to be the most intensively designed green space layouts. Both distribution and species composition in domestic gardens were socioeconomic-driven. For instance, palm trees were characteristic of fortunate quarters while fruitbearing ornamental such as Psidium guajava and Persea americana were common within scattered and informal settlements. Markhamia lutea, Erythina abyssinica, Euphorbia candelabrum, Phoenix reclinata and Acacia sieberiana are among native taxa that thrive to keep a place in the city. Euphorbia tirucalli, a native tree that is widespread in home compound fences within informal settlements, is significantly declining as modern housing expands and concrete-based fences replace live enclosures.  相似文献   

15.
Residential greenspace has great intracity variations. Its driving factors have been widely investigated in Western countries (e.g., in Europe and North America), where residential areas are mostly privately owned, but few studies have examined the determinants of residential greenspace in China, where land is owned by the government. Taking the subtropical city of Changsha, China, as an example, this study mapped the percent green cover (PGC) in residential quarters with a fine-resolution satellite image. We also investigated its driving factors measured from multisource geospatial data. The results show that (1) the PGC in the residential quarters showed great spatial variation, with an average of 36.6% (0–85.7%) and a standard deviation of 18.3%. (2) Urban form, biophysical context, and socioeconomic factors together explained 49.18% of the variation in the PGC, and they independently explained 22.87%, 11.17%, and 2.31% of the variation, respectively. (3) Residential quarter size, PGC in the surrounding buffer zone, residential quarter age, housing value, and population density significantly and positively impact the PGC, while percent building cover, floor area ratio, and distance to city center had significant negative impacts. The strongest positive and negative impacts came from PGC in the surrounding buffer zone and percent building cover, respectively. Socioeconomic factors, the dominant driving factors in Western countries, show little impact on residential PGC. These findings expand our understanding of the intracity variation in greenspace coverage and the driving factors, which sheds light on the effective planning and management of urban greenspaces in China.  相似文献   

16.
The desire to improve urban sustainability is motivating many city planners to adopt growth strategies that increase residential density, leading to substantial changes to urban landscapes. What effect this change will have on biodiversity remains unclear, but it is expected that the role of public greenspace in providing wildlife habitat will become critical. We explored the role of urban “pocket parks” as habitat for birds, and how this role changed with increasing residential density in the surrounding neighbourhood. We found that parks in neighbourhoods with high levels of public greenspace (corresponding to less residential land) supported more bird species and individuals overall, and more woodland-dependent species, insectivores and hollow-nesters. Total greenspace area was more important (included in the best ranked models for all bird responses) than the configuration (number, average size and connectivity) of greenspace patches. The majority of species were common suburban birds, indicating that species we assume are tolerant to urban areas will be negatively affected by increasing residential density. Parks form part of an interconnected network of urban open space. For parks to continue to support a diverse native bird community, the network must be viewed, managed, and maintained in its entirety. We suggest three key management actions to improve the bird diversity values of urban greenspaces in compact cities: (1) Increase urban greenspace cover in residential neighbourhoods. (2) Increase vegetation structure in greenspace. (3) Encourage homeowners to plant trees and shrubs.  相似文献   

17.
Recent studies have emphasized the presence of microclimates in urban settings, but most do not have the high resolution observations necessary to understand the interactions taking place at a neighborhood scale. This study used a network of 10 identical weather stations and high resolution land cover data in Knoxville, Tennessee, to analyze the microclimates of a medium-sized city with a temperate climate. Two stations were installed in each of four urban neighborhoods in locations with varying localized tree cover, and two additional stations were installed in the center of downtown and in a nearby urban nature center. The intra-neighborhood results suggested that there is significant temperature variability within a single neighborhood based on the tree canopy density immediately surrounding a given weather station. However, the inter-neighborhood variability (differences between neighborhoods) was similar in magnitude, which suggests that the overall differences in neighborhood characteristics also have an effect on climate. Land cover at the neighborhood scale (in particular tree canopy percentages at the 500-m radii) had the highest correlation with the minimum daily temperature (Tmin) during the summer season. Maximum daily temperature (Tmax) relied most on the distance of each station from Downtown and the amount of impervious area in the 50 m surrounding each station. Tmax was also most influenced by surrounding land cover during dry conditions (a Dry Moderate air mass). Overall, highly localized impervious land cover percentages and larger-scale forested canopy were important in explaining temperature fluctuation, pointing to the importance of scale in microclimate assessments. Dry air masses enhanced the relationship between land cover and temperature during the day, while moist air masses did the same overnight. These data can be used to better inform planning strategies to build resiliency to extreme heat into urban environments by considering the influence of tree canopy.  相似文献   

18.

Context

With rapidly expanding urban regions, the effects of land cover changes on urban surface temperatures and the consequences of these changes for human health are becoming progressively larger problems.

Objectives

We investigated residential parcel and neighborhood scale variations in urban land surface temperature, land cover, and residents’ perceptions of landscapes and heat illnesses in the subtropical desert city of Phoenix, AZ USA.

Methods

We conducted an airborne imaging campaign that acquired high resolution urban land surface temperature data (7 m/pixel) during the day and night. We performed a geographic overlay of these data with high resolution land cover maps, parcel boundaries, neighborhood boundaries, and a household survey.

Results

Land cover composition, including percentages of vegetated, building, and road areas, and values for NDVI, and albedo, was correlated with residential parcel surface temperatures and the effects differed between day and night. Vegetation was more effective at cooling hotter neighborhoods. We found consistencies between heat risk factors in neighborhood environments and residents’ perceptions of these factors. Symptoms of heat-related illness were correlated with parcel scale surface temperature patterns during the daytime but no corresponding relationship was observed with nighttime surface temperatures.

Conclusions

Residents’ experiences of heat vulnerability were related to the daytime land surface thermal environment, which is influenced by micro-scale variation in land cover composition. These results provide a first look at parcel-scale causes and consequences of urban surface temperature variation and provide a critically needed perspective on heat vulnerability assessment studies conducted at much coarser scales.
  相似文献   

19.
Urban forestry is increasingly vital for both wildlife conservation and human use, despite frequent conflicts between these functions. A fundamental task in urban habitat and recreation forestry is the identification of those habitat characteristics important for animal species and the evaluation of these within the geographies of human presence, urban proximity and land cover variation and change. This paper examines the habitat characteristics for birds in urban built, green and greenbelt areas of Ottawa, Canada, and an area of continuous Ontario forest, to determine the effects of vegetation density and patch size, and human presence on bird presence. Bird presence was measured by point counts, and land cover was mapped using field observation and aerial photographs (1955 and 1999). At the species level, the pre-dominantly forest birds were affected by human presence and were primarily associated with tree stands in the greenbelt and continuous forest. In dense urban areas there were larger numbers of a few ‘generalist’ species. Both forested and urban (residential/commercial) environments increased in area between 1955 and 1999, creating the two types of land cover favouring the largest number of birds, while the less habituated grass/farmed areas declined in area. More informed bird conservation and recreation management will depend on paying greater attention to vegetation cover combinations with urban development.  相似文献   

20.
Urban ecosystem services are generated in a diverse set of natural and managed urban green areas, including parks, urban forests, cemeteries, vegetated corridors, vacant lots, gardens, yards, and campus areas. Private gardens are generally undervalued for the ecosystem services they provide along with the other urban green areas.This paper aims to calculate three regulating ecosystem services; runoff retention, carbon storage and sequestration generated by the Ege University Rectorship Garden, which is one of the few former Levantine gardens remaining in the highly urbanized Bornova district in İzmir. The carbon storage and sequestration capacity of the trees in the area was calculated based on allometric equations. Runoff retention was computed by using the SCS-CN method. Findings show that pervious surfaces cover approximately two-thirds of the garden with 1203 trees. The estimated carbon storage of both the above and below-ground parts of the trees in the garden is 648.25 t. The total annual carbon sequestration rate is estimated to be 7.87 t year−1 (0.10 kg m−2). The potential storm water runoff value was predicted to be approximately 7,018.9 m3. This indicates that the garden has a high value of runoff retention and substantial capacity carbon storage and sequestration.It can be concluded that private gardens and associated ecosystem services in urban landscapes can play an important role in enhancing the quality of life in cities. Therefore, an integral approach is needed where all types of green areas are planned and managed in a systematic way, so that they can provide maximum services.  相似文献   

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