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1.
In urban areas the density of breeding tits (Paridae) is generally higher and reproductive performance lower compared to rural areas. To explain these landscape differences several hypotheses have been proposed, e.g. differences in habitat quality, inter- and intra-specific competition, predation and food abundance. How breeding performance of birds within remnants of natural vegetation in urban areas is affected by adjacent matrix has been less studied. We performed an experimental study in four urban woodlands surrounded by three types of habitat matrix: residential, high-rise building and grassland/golf course. We placed 300 nest boxes for tits (great tit Parus major and blue tit Cyanistes caeruleus) in 15 transects that were 200 m long, extending from the adjacent matrix 150 m into urban woodland. Density of breeding great tit pairs was highest in residential areas and hatch date was earlier in the residential habitat compared to the other two habitats, however, nestling condition was lower in residential areas. Hatching date was earlier but hatching spread (heaviest nestling/lightest nestling) higher in the three types of urban matrix than inside the urban woodlands. In contrast to previous large-scale comparisons of urban and rural matrix, we almost exclusively found differences in qualitative measures (nestling condition and hatchling spread) at the small scale in which this study was conducted. Adjacent matrix affect great tits breeding in remnant urban woodlands, thus we suggest that management of the surrounding matrix should be included in conservation plans for urban woodlands.  相似文献   

2.
The influence of environmental parameters on epigeic beetle communities of forest fragments in an urbanization gradient was studied in Berlin. Eight deciduous forests along a rural to urban gradient were sampled with pitfall traps. Species richness did not decline across the rural to urban gradient. As expected, impervious surface cover as an indicator of urbanization correlated not only with habitat fragmentation and heat island effect but also with altered soil properties. The proportion of forest specialist staphylinid species decreased with increasing urbanization. The differences between staphylinid communities of neighboring forest fragments were enhanced in the most urban parts, probably due to increased habitat fragmentation. Furthermore, the loss of flightless species with increasing habitat isolation emphasized the influence of habitat fragmentation. The carabid communities revealed the urbanization effects not as clearly as the staphylinid communities, but both taxa revealed that direct anthropogenic habitat alteration, indicated by removal of decaying wood, favors open-habitat specialists. The extent of the urbanization influence seems to vary seasonally. Environmental parameters associated with urbanization explain the ordination of species communities in the winter better than in the summer. Heat island effect is suggested as an explanation for this difference.  相似文献   

3.
Urbanization creates new habitats with novel benefits and challenges not found in natural systems. How a species fares in urban habitats is largely dependent on its life history, yet predicting the response of individual species to urbanization remains a challenge. While some species thrive in urban areas, others do poorly or are not present at all. Mountain chickadees (Poecile gambeli) are year-round residents of montane regions of western North America. Commonly found in higher-elevation coniferous forests, these birds can also be found in urban areas where they will regularly visit bird feeders and nest in nest boxes. We monitored mountain chickadees nesting along a habitat gradient, from natural habitat to suburban areas, to determine if the degree of urbanization was associated with: clutch size and success; nestling growth rates; or variation in parental size and age. Females nesting in urbanized areas initiated clutches earlier in the breeding season than those in natural areas, but neither fledging success nor the rate of nestling mass-change differed between habitats. Nestling feather growth-rate increased with later first egg dates in both habitats, and the magnitude of this increase was greatest in urban habitats. We found no difference in the proportion of first-time breeders versus experienced breeders between habitat types, nor any differences in male or female mass or size. Our results indicate no detriment to nesting in urban habitats, suggesting mountain chickadees are able to adapt to moderate urbanization much like other members of the Paridae family.  相似文献   

4.
Urban areas are increasing in number, extent, and human population density worldwide. There is potential to mitigate negative impacts of urbanization to native pond-breeding amphibians by providing habitat in both remnant natural and constructed wetlands. This study examines amphibian use of potential breeding sites in natural and constructed ponds in a large metropolitan area to investigate habitat characteristics that are associated with successful breeding. I surveyed 62 ponds over three breeding seasons in Portland, Oregon, measuring eleven habitat characteristics that may influence their successful breeding: pond depth, nitrate level, aquatic refugia, aquatic vegetation, surrounding vegetation, pond permanence, presence of fish and of introduced bullfrogs, surrounding road density and forest cover, and whether they were constructed or remnant natural ponds. Five of the six native pond-breeding species that occur in the region were regularly found breeding in city ponds. Surrounding forest cover and amount of aquatic vegetation were highly associated with breeding, indicating that preserving and planting vegetation likely benefits urban amphibians. Non-native bullfrogs were not associated with native species richness. Surprisingly, whether a pond was natural or constructed was also only weakly associated with native species breeding, and the trend was towards higher presence for all species in constructed ponds. This indicates that novel, human-dominated areas can provide habitat for these species. Consideration of habitat characteristics associated with breeding success in urban pond management will likely benefit native amphibians in these rapidly expanding landscapes.  相似文献   

5.
Foraging decisions reflect a trade-off between the benefits of acquiring food and the costs of movement. Changes in the biotic and abiotic environment associated with urbanization can alter this trade-off and modify foraging decisions. We experimentally manipulated foraging opportunities for two Anolis lizard species – the brown anole (A. sagrei) in Florida and the crested anole (A. cristatellus) in Puerto Rico – to assess whether foraging behavior differs between habitats varying in their degree of urbanization. In both urban and natural forest habitats, we measured the latency of perched anoles to feed from an experimental feeding tray. We manipulated perch availability and predator presence, while also taking into account population (e.g., conspecific density) and individual-level factors (e.g., body temperature) to evaluate whether and how these contribute to between-habitat differences in foraging behavior. In both species, urban anoles had longer latencies to feed and lower overall response rates compared to lizards from forests. Urban anoles were also larger (i.e., snout-vent length and mass) in both species and urban A. sagrei were in better body condition than the natural forest population. We postulate that the observed patterns in foraging behavior are driven by differences in perceived predation risk, foraging motivation, or neophobia. Although we are unable to identify the mechanism(s) driving these differences, the substantial differences in urban versus forest anole foraging behavior emphasizes the importance of understanding how urbanization influences animal populations and their persistence in anthropogenically-modified environments.  相似文献   

6.

Urban forest ecosystems, the structure, and functions therein are subjected to anthropogenic disturbances. Native and sensitive species from those forests might be lost due to such disturbances. At the same time, supplemented anthropogenic resources might create opportunities for exotic and invasive species. Although invasive species are considered one of the major threats to the urban biodiversity and ecosystems, the research on invasion dynamics in the Himalayas has primarily focused on the impacts of invasion on forest structure and productivity. This study aims to understand the influence of forest structure and anthropogenic factors in invasion success that are poorly covered in the existing literature. We selected 11 urban forest patches for the study considering the presence-absence of selected invasive species and structural attributes. We used Principal Component Analysis (PCA) to reduce co-linearity in the covariates and generalized linear mixed effects model (GLMM) to identify the factors affecting invasion success. We found that forest structural attributes, namely, tree diameter, height and canopy cover, and anthropogenic disturbances regulate invasion success in urban forests. This implies that maintaining urban forest structural attributes, especially the stands with large-sized trees, is essential to control invasion in the context of urbanization.

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7.
The effects of urban disturbance are critical to understand, as the majority of the world??s population now resides in urban centers. For example, urbanization often leads to reduced species diversity at the expense of a few urban-adapted taxa. However, it remains unclear why some taxa thrive following human disturbance whereas others do poorly. The western black widow spider, Latrodectus hesperus, thrives in disturbed, urban habitat??often forming dense aggregations (i.e., infestations) relative to typical low-density, desert populations. We examined the population dynamics of ten black widow aggregations spread across metropolitan Phoenix, AZ, during the peak of the breeding season (June?CAugust). Here we show that prey abundance, female mass, web volume and population density exhibit minimal temporal variation across the breeding season, but that prey abundance, female mass and population density show significant spatial variation across the ten urban aggregations. Our measure of prey abundance and foraging success, the number of prey carcasses found in black widow webs, shared a strong positive relationship with female mass and population density, but not with web volume. Surprisingly, female mass, web volume and population density were not correlated with each other. The abiotic variables we measured at each site did a poor job of explaining black widow population parameters, although we did find a marginal trend for more recent developments to harbor denser black widow aggregations. Our findings support the generalization that urbanization heightens spatial variation, and we suggest that local urban prey abundance is influential in promoting urban infestations full of heavy, fecund female black widows. Studies of the population ecology of urban pests are necessary to identify the mechanisms allowing some species to thrive following human disturbance while much native biodiversity is lost following urbanization.  相似文献   

8.
Urbanization is a pervasive and growing threat to amphibian populations globally. Although the number of studies is increasing, many aspects of basic amphibian biology have not been investigated in urban settings. We reviewed 32 urban studies from North America and quantified the number of species studied and their response to urbanization. We examined existing research on breeding habitats, life-history stages, movement patterns, and habitat use relative to urbanization. We found amphibians as a whole respond negatively to urbanization (69 reported responses were negative, 6 were positive and 35 showed no effect). We caution, however, that many North American species still lack or are associated with conflicting information regarding species-specific responses (e.g., 89 potential responses were unknown). Approximately 40% of all anuran and 14% of caudate species in North America were investigated in the literature; however, the most diverse genera (e.g., Plethodon and Eurycea) were the most understudied likely due to their cryptic terrestrial lifestyles and biases in sampling protocols that assess wetland habitats via call surveys. Research on movement and small scale habitat use was deficient. Adult, juvenile, tadpole, and egg mass life-history stages commonly served as direct measures of species presence and abundance; however, such data do not accurately reflect recruitment into subsequent age classes and population persistence. The lack of data on many North American species may be contributing to poor management of urban amphibian populations and their habitats.  相似文献   

9.

Urban environments present wildlife with major challenges and yet surprising numbers of species have colonised towns and cities globally. Despite the growing realisation that urban centres can be important habitats for wildlife, why some species do better than others in urban environments remains poorly understood. Here, we compare the breeding performance of an apex predator, the peregrine falcon (Falco peregrinus), in urban and rural environments, and test whether variation in reproductive success between and within environments is driven by prey. Historical breeding data were collected from raptor study groups across Great Britain between 2006 and 2016, from 22 urban and 58 rural nest sites, involving 101 and 326 nesting attempts, respectively. Prey density, biomass and diversity around the individual nests was estimated using modelled estimates from a national bird census. Urban peregrines produced more fledglings and had a higher overall nesting success (i.e. whether a nesting attempt was successful or unsuccessful) than rural peregrines. Prey density and biomass were significantly higher, and diversity significantly lower, in the urban sites, and explained the variation in reproductive success within both the urban and rural environments. Therefore, urban environments in Great Britain appear to provide peregrine falcons with superior habitats in terms of prey availability compared to rural habitats. We conclude that some apex predators can benefit from urban environments and that urban planning has the potential to benefit biodiversity across many trophic levels.

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10.
The increasing numbers and negative impacts of invasive species have prompted research on the relationship between human activities and the success of invasive horticultural plants. In this study, we use population genetic relationships to model the escape of a common garden vine, exotic Wisteria, into natural habitats. Urban and naturalized Wisteria populations in Charleston, South Carolina and Tallahassee, Florida were investigated using a combination of chloroplast, mitochondrial and nuclear DNA markers. Fifty-nine of 72 (81.9%) Wisteria collections were hybrids of Wisteria sinensis and W. floribunda. Chi-square analysis of the distribution of shared W. floribunda haplotypes among naturalized and urban populations supports the relationship of time with invasion success. Naturalized populations were more similar to those in historic neighborhoods. The most common haplotype, F1, was encountered 22 times but its distribution was not significantly different between urban and naturalized populations. In contrast, a significantly higher proportion of haplotype F2 found in naturalized populations suggests that selection may also be acting within these populations. Finally, due to extensive human dispersal, there is no relationship between genetic distance and geographical distance among the populations sampled. We conclude that Wisteria’s long history of horticulture, rampant hybridization, and human-aided dispersal are all implicated in the successful ability of these plants to invade natural habitats throughout the USA.  相似文献   

11.
Urbanization leads to long-term modification of landscapes by habitat loss, fragmentation, and the creation of new habitats. Species’ distributions respond to these modifications of habitat availability, but the combination of parameters and scale at which habitat alteration most strongly influences species distributions is poorly understood. We evaluated responses of neotropical migratory birds, a group known to be sensitive to habitat modification, across a gradient of urbanization in the southeastern United States. Thirteen Breeding Bird Survey routes, each with 40 to 50 point counts, were used to quantify species richness across the gradient of urbanization extending from downtown areas of Columbus, GA to natural woodlands. Buffers of 100, 200, and 1000 m radii were constructed from remote images around each counting point to quantify land-use with the goal of evaluating land-use parameters and scales that best described spatial variation in migrant bird species richness. Within each buffer we quantified the proportion of each cover type and within the 1000 m buffers we included several configuration parameters. We used an information-theoretic approach to separate models whose predictor variables were land-use parameters. Because measures of landscape configuration were all correlated with urban cover, these variables were entered separately. In 2002, the best model was composed of large-scale urban cover (negative effect) and mid-scale mixed hardwoods (negative and positive effect) and transitional cover (negative and positive effect) as well as the interaction between the latter two terms (positive effect). In 2003, the best model was composed of weighted edge density (negative effect), mid-scale mixed hardwood cover (negative and positive effect) and large scale transitional cover (positive effect) and the interaction between mixed hardwoods and weighted edge density (positive effect). Our results indicate that large scale habitat attributes influence the local species richness of migrant birds more than smaller scales. These results also indicate that urbanization, through increased urban cover or increasing edge contrast, has strong negative effects on species richness. Our findings support the contention that the conservation value of small woodlots in urban settings may be minimal and suggest that conservation of migratory birds will be best achieved by giving higher priority to sites where urban cover is still low and by preserving large areas of “green space” in urbanizing landscapes. The negative influence of urban cover combined with relatively minor effects of non-urban habitats on distributions of neotropical migratory birds indicates that continued urbanization of landscapes is a serious concern for conservation efforts.  相似文献   

12.
Forest habitat is important for a variety of woodpecker species, and is under pressure from urbanization. Red-headed Woodpeckers (Melanerpes erythrocephalus; RHWO) were once abundant across Eastern North America, and their populations have been declining since the 1960s. Their distribution encompasses urban centers, and since urban habitats differ from natural forest areas, our goal was to understand RHWO nest-site selection in an urban context. We addressed two main questions 1) what are the characteristics of RHWO nest selection across multiple spatial scales and 2) how do RHWO nest tree characteristics in city parks compare to those in forest preserves? This work was done in Cook County, IL, which includes Chicago, the third-largest city in the USA by population. We examined 34 RHWO nest trees used between 2010 and 2013, their surrounding habitat, and the landscape within a 1 km radius. Used trees and habitats were compared to paired unused trees and habitats, and landscape-scale characteristics were compared to random locations. Advanced decay of the nest tree, low canopy cover and increased presence of fungus on trees in the surrounding habitat were the best predictors of RHWO nesting in the area. Nests were most commonly found in forested areas outside of dense urban areas. However, we did not detect significant differences in the characteristics of the nest trees located in forest preserves and city parks. Our findings are consistent with nest selection studies in rural and natural areas, suggesting that forest habitats in metropolitan landscapes can support RHWO nesting.  相似文献   

13.
We examined the relationship between bat species activity and composition and the extent of forest cover and urbanization in and adjacent to 11 U.S. National Park Service, National Capital Region Parks in Maryland, Virginia, West Virginia, and Washington, D.C., from 2003–2004, using mist nets, harp traps, acoustical detectors, and visual observations in a variety of habitats. Our efforts included 363 trap nights across 74 sites along with acoustical sampling at 362 sites. We captured 383 bats and identified 6,380 echolocation passes of 6 species. Both overall and species-specific activities were affected more by forest fragmentation within parks than by urbanization adjacent to parks. With an ability to exploit anthropogenic structures for day-roosts, big brown bats (Eptesicus fuscus) were the most ubiquitous and probably the most abundant species in NCR Parks, particularly in forested, urban parks. Northern myotis (Myotis septentrionalis), and to a lesser extent, little brown myotis (Myotis lucifugus) were more prevalent in forested, rural parks of the Ridge and Valley and Blue Ridge than in eastern, less forested urban parks of the Piedmont and Coastal Plain physiographic provinces. Retention of larger, residual forest tracts and day-roosting habitat (i.e., trees and snags) would be beneficial to most species, as urban expansion continues throughout the region.  相似文献   

14.
We evaluated the richness, composition and abundance of bird communities in three urban forests of Mediterranean France during winter and spring. The urban forests differed in size, composition, structure, age of vegetation, and location relative to the city centre. Estimated species richness across all three urban forest parks was 45 species. Twenty six (26) species were recorded in both winter and spring, whereas ten species were recorded only in spring, and six were recorded only in winter. Distribution, turnover, and type of bird foraging guild were related to characteristics of each urban forest and season. During spring migration, more species were recorded in sampling units (250?×?250 m) within the largest and most natural urban forest located in the outskirts of Montpellier, whereas during winter, more species were recorded in the most urbanized park (i.e., a botanical garden dominated by exotic vegetation), which was located in the city centre. Insectivorous birds were more abundant in winter, whereas seedeaters associated with wooded habitats were recorded more frequently in spring. Our results suggested that different kinds of urban forests are important modulators of urban bird communities and they are necessary to maintain the diversity of migratory and resident birds as well as increasing the environmental quality of urban areas.  相似文献   

15.
Investigations of urbanization effects on birds have focused mainly on breeding traits expressed after the nest-building stage (e.g. first-egg date, clutch size, breeding success, and offspring characteristics). Urban studies largely ignored how and why the aspects of nest building might be associated with the degree of urbanization. As urban environments are expected to present novel environmental changes relative to rural environments, it is important to evaluate how nest-building behavior is impacted by vegetation modifications associated with urbanization. To examine nest design in a Mediterranean city environment, we allowed urban great tits (Parus major) to breed in nest boxes in areas that differed in local vegetation cover. We found that different measures of nest size or mass were not associated with vegetation cover. In particular, nests located adjacent to streets with lower vegetation cover were not smaller or lighter than nests in parks with higher vegetation cover. Nests adjacent to streets contained more pine needles than nests in parks. In addition, in nests adjacent to streets, nests from boxes attached to pine trees contained more pine needles than nests from boxes attached to other trees. We suggest that urban-related alterations in vegetation cover do not directly impose physical limits on nest size in species that are opportunistic in the selection of nesting material. However, nest composition as reflected in the use of pine needles was clearly affected by habitat type and the planted tree species present, which implies that rapid habitat change impacts nest composition. We do not exclude that urbanization might impact other aspects of nest building behaviour not covered in our study (e.g. costs of searching for nest material), and that the strengths of the associations between urbanization and nest structures might differ among study populations or species.  相似文献   

16.

Research in urban ecology is growing rapidly in response to the exponential growth of the urban environment. However, few studies have focused on tropical megacities, and on the interplay between predators’ habitat selection and human socio-economic aspects, which may mediate their resilience and coexistence with humans. We examined mechanisms of breeding habitat selection by a synanthropic raptor, the Black Kite Milvus migrans, in Delhi (India) where kites mainly subsist on: (1) human refuse and its associated prey-fauna, and (2) ritualised feeding of kites, particularly practised by Muslims. We used mixed effects models to test the effect of urban habitat configuration and human practices on habitat selection, site occupancy and breeding success. Kite habitat decisions, territory occupancy and breeding success were tightly enmeshed with human activities: kites preferred areas with high human density, poor waste management and a road configuration that facilitated better access to resources provided by humans, in particular to Muslim colonies that provided ritual subsidies. Furthermore, kites bred at ‘clean’ sites with less human refuse only when close to Muslim colonies, suggesting that the proximity to ritual-feeding sites modulated the suitability of other habitats. Rather than a nuisance to avoid, as previously portrayed, humans were a keenly-targeted foraging resource, which tied a predator’s distribution to human activities, politics, history, socio-economics and urban planning at multiple spatio-temporal scales. Many synurbic species may exploit humans in more subtle and direct ways than was previously assumed, but uncovering them will require greater integration of human socio-cultural estimates in urban ecological research.

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17.
Despite their designation as nationally important habitats in the UK, ponds are among the least well studied of urban habitats. Ponds, as well as existing in a physical landscape, are part of human socio-economic landscapes, especially those in towns and cities. Socio-economic, ecological and land cover data were collected from thirty seven ponds in the urban area of Halton, northwest England over a 3?year period. Significant variation was observed in the CCI Scores for ponds in different Output Area Classifications. Within postcode districts there was a significantly negative correlation between increasing house prices and decreasing BMWP scores. This research offers insights into the impact of urban development on pond ecology, and suggests the potential impacts of future developments and how these may be ameliorated. The research contributes towards the understanding of freshwater systems in the urban context and the relationship between the human and natural elements of urban green and blue spaces.  相似文献   

18.
Mediterranean-type ecosystems are one of the most affected environments by habitat loss and fragmentation due to urban development, however only few studies have evaluated the effects of urbanization on the biodiversity of remnant fragments in these ecosystems. This study aims to evaluate the effects of urban development over small mammal assemblages inhabiting isolated forest fragments of an urban area of Chilean Mediterranean zone. We compared abundance and richness of small mammal assemblages of six remnant fragments within an urban matrix, and six fragments similar in area and habitat characteristics with those of urban area, but surrounded by a rural matrix. We found that small mammal assemblages differ considerably among fragments types (urban vs rural), with lack of endemic species from urban fragments and with high proportion of introduced rodents in urban fragments. Furthermore abundance of small mammals was higher in rural than in urban fragments. In urban areas small mammal abundance and richness were not correlated with any of the explanatory variables assessed (woody cover, flora heterogeneity, fragment area, perimeter/area ratio). However in rural fragments small mammal richness was negatively correlated with flora heterogeneity and the abundance of small mammals was positively correlated with perimeter/area ratio. These results reveal important differences within the effects of fragmentation over small mammal assemblages among the two types of fragments assessed. Our findings suggest that in forest fragments isolated by urbanization, larger areas with good quality habitats are not sufficient to maintain native small mammal population.  相似文献   

19.
Changes in riparian woody plant assemblages are anticipated in the southeastern United States due to increases in urbanization rates. Because riparian forests serve important roles in maintaining water quality and biodiversity, understanding how they respond to urbanization is crucial. The objective of this study was to examine forest structure and woody vegetation diversity indices of riparian communities in response to an urbanization gradient in West Georgia, USA. Measures of forest structure and diversity were compared to measures of urbanization and land cover. Although Liquidambar styracifluaand Quercus nigrawere dominant species in the forest stand and regeneration layer for all riparian communities, the invasive, non-native shrub Ligustrum sinense was the most dominant species observed in the regeneration layer for urban, developing, and agriculture communities. The proportion of non-native species in the forest stand and regeneration layer decreased and Shannon diversity of the regeneration layer increased with increasing distance from the urban center. Shifts in diversity indicate that anthropogenic disturbance may subdue the ability of diverse communities to resist non-native plant invasions.  相似文献   

20.
Lv  Hailiang  Yang  Yanbo  Zhang  Dan  Du  Hongju  Zhang  Jianyu  Wang  Wenjie  He  Xingyuan 《Urban Ecosystems》2019,22(4):631-642

To maximize the ecological services of urban forests, a better understanding of the effects of urbanization on urban forest characteristics, landscape metrics, and their associations is needed for landscape-related regulations in space-limited green infrastructure of metropolitan regions. In this study, Harbin, a typical fast-growing provincial-capital city in Northeast China, is used as a case study. Based on remote sensing images, field surveys, and correlation and variation partitioning analyses, we conclude that landscape characteristics and forest attributes have large variations among different urbanization intensity (UI) regions. Forest patch density (PD), landscape shape index, woody plants species richness, and the Shannon–Wiener index (H′) increased linearly, while stem section area and tree height decreased linearly with the increasing of UIs. UI had a greater influence on tree size and forest community attributes than the forest landscape pattern. Accordingly, any landscape regulation on forest attributes should be implemented according to UIs. In addition, Euclidean nearest neighbor distance(ENN-MN), mean perimeter-area ratio (PARA-MN), fractal dimension index(FRAC-MN), and PD could probably indicate forest attributes the most, e.g., the increase of PARA-MN may be accompanied with taller trees in low and heavy UI regions, but lower woody plants species evenness in low and medium UI regions. More diversified woody plants species, and afforested areas should be advocated in a low UI region, while in a heavy UI region, the conservation of large trees should be implemented. Our results highlight that the implementation of urban forest management should vary according to different urbanization regions to maximize ecological services.

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