Sacred sites as habitats of culturally important plant species in an Indian megacity

Cultural ecosystem services related to urban green spaces contribute significantly to liveable cities. While previous studies highlight the intersection of cultural ecosystem services with societal values, spiritual or religious values associated with urban nature have received less attention. In India, as in other parts of the world, sacred sites are known for their biological richness, but analyses from urban sacred sites are largely missing. Based on a stratified random sampling approach, we analysed the cultivated and wild plant species assemblages of 69 sacred sites in the megacity of Bengaluru, India, in relation to biological and cultural features, and parameters related to the urban matrix and type of sacred sites (temple vs. katte). Unlike other urban studies, we found a dominance of native species in the cultivated and spontaneous species pools (121 species in total), with Ficus religiosa and Azadirachta indica as most frequently planted species. Culturally relevant species prevailed in the species pool (89%), with overlaps between religious (36%), medicinal (50%) and ornamental (62%) plants; only 11% of species were weeds. Urban matrix parameters (age of development, housing density) and size and type of sacred sites were related to differences in species assemblages. We identified key species for different classes of age and housing density, and for types of sacred sites. Our study demonstrates that urban sacred sites have an important potential in harbouring both native and culturally significant species that can support urban livelihoods in developing countries by a range of cultural and provisioning ecosystem services, including medicinal uses. As such sites are conserved by communities for spiritual or cultural beliefs, local biodiversity can be enhanced, e.g. by adapting management practices through community participation. This would strengthen the important contribution of sacred sites within the green infrastructure of rapidly growing megacities.     

The designation of a historical site to maintain plant diversity in the Tokyo metropolitan region

Although urban habitats contribute to the conservation of species diversity, urbanization has significantly reduced biodiversity by causing environmental changes such as habitat loss and fragmentation. Therefore, research on urban biodiversity studies has become increasingly important. Historical heritage sites are recognized as important habitats in remnant green spaces in urban areas. We aimed to evaluate the role of historical sites in conserving biodiversity in urban areas. As the land in these historical sites is not modified, they have the potential to conserve biodiversity through continued maintenance activities such as mowing and tree cutting. In Japan, Tamagawa-josui, a waterway that runs from west to east through the Tokyo megacity (35° 40′ N, 139° 25′ E), has been recognized as a civil engineering heritage landmark that preserves water utilization technology from the early modern period (1600s, Edo-era). The present study examined the relationships between plant diversity and green space in a historic site of a megacity (i.e., Tamagawa-josui) and determined the factors that influence plant diversity. Specifically, we examined the relationships between plant species indices (species richness and species compositions) and environmental factors (management, environmental conditions, and landscape factors). The present study analyzed spatial changes in the plant species composition in Tamagawa-josui. We demonstrated that tree canopy openness was positively correlated with plant species richness, and the increased disturbance associated with developing historical sites as urban parks was negatively correlated with native plant species richness. In addition, there was significant species turnover in the plant community from upstream to downstream in Tamagawa-josui, which could largely be explained by spatial factors. We demonstrated that historical sites can provide potential habitats for the conservation of the plant species diversity, which is based on the effectiveness of the management of their vegetation.     

Cemeteries support avian diversity likewise urban parks in European cities: Assessing taxonomic,evolutionary and functional diversity

The aim of this study was to explore different components of avian diversity in two types of urban green areas, parks and cemeteries, in four European countries in relation to environmental characteristics. We studied bird species richness, functional diversity and evolutionary distinctiveness in 79 parks and 90 cemeteries located in four European countries: the Czech Republic, France, Italy and Poland.First, we found no significant differences between cemeteries and parks in bird diversity. However, in both parks and cemeteries, only: two community metrics were affected by different environmental characteristics, including local vegetation structure and presence of human-related structures. Species richness was positively correlated with tree coverage and site size, functional diversity was unrelated to any of the measured variables, while the mean evolutionary distinctiveness score was positively correlated with tree coverage and negatively associated with the coverage of flowerbeds and number of street lamps.Our findings can be useful for urban planning: by increasing tree coverage and site size it is possible to increase both taxonomic richness and evolutionary uniqueness of bird communities. In both parks and cemeteries, the potential association between light pollution and bird species richness was negligible. We also identified some thresholds where bird diversity was higher. Bird species richness was maximized in parks/cemeteries larger than 1.4 ha, with grass coverage lower than 65%. The evolutionary uniqueness of bird communities was higher in areas with tree coverage higher than 45%. In conclusion, the findings of this study provide evidence that cemeteries work similarly than urban parks supporting avian diversity.     

Trees in urban religious sites: An analysis of their diversity in Arequipa,Peru

Facing the trend of rapid urbanization, conserving the biodiversity of urban green spaces is a challenge, particularly in a developing region like Latin America. In this sense, it is known that urban sacred sites have significant cultural and conservation significance within cities. However, more needs to be studied about the vegetation they house. Given the scientific gap, the composition, richness and abundance of trees in urban religious sites of Arequipa established since the 16th century were examined, and temporal changes in the composition and distribution of trees between ancient and modern sites were identified. 749 trees of 54 species were recorded in 26 religious’ sites. A higher proportion of exotic species (74%) corresponds in greater quantity to fruit trees (52%). There were no significant differences in tree richness and abundance between ancient and modern sites. However, the ancient sites had higher richness (96.3%) and abundance (71.4%). Likewise, ancient sites present a preference for growing fruit trees in orchards and cloister gardens, unlike modern sites focused on increasing ornamental trees, with a predominance of conifers and palms. Despite the long history of the monuments, the size of the site and the green areas significantly influenced the richness and abundance; similarly, the care of the gardens greatly influenced a site that stored greater diversity and abundance. In this way, it is demonstrated that these culturally significant places house an important tree diversity, with species of nutritional and ornamental value for the self-provisioning of the religious and the beautification of the gardens. In addition, they contribute to environmental sustainability, providing different ecosystem services to cities with rapid population growth.     

Taxonomic diversity,functional diversity and evolutionary uniqueness in bird communities of Beijing's urban parks: Effects of land use and vegetation structure

The importance of biodiversity conservation is well recognized, and the loss of biodiversity is particularly evident in highly urbanized areas. On the other hand, green spaces inside cities, as parks, can provide a resource for maintaining and increasing biodiversity, especially for bird species. However, only a few studies have addressed the effects of vegetation structure and land use composition on different components of biodiversity.Here, we explored the response of bird community composition to environmental differences related to land use composition and vegetation structure in green spaces in the city of Beijing, China. We compared the values of taxonomic diversity, functional diversity and community evolutionary distinctiveness in breeding bird communities, among ten urban parks of the world's third most populous city. Variation partitioning analysis and generalized linear mixed models were used to explore the unique and shared effects of land use composition and vegetation structure on each biodiversity metric.Park size was not associated with the diversity of bird communities in Beijing. Land use composition was the best predictor of change in bird community composition, followed by vegetation structure at ground level and the intersection between land use and vegetation structure at tree level. Water coverage increased bird species richness, while the presence of large trees increased both taxonomic diversity and bird functional richness in urban parks. Finally, the presence of patches of deciduous trees showed a positive effect on the average score of evolutionary distinctiveness of bird communities. In conclusion, we highlight that different elements of the environment are supporting different components of bird community diversity.     

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.     

Bird diversity in urban green space: A large-scale analysis of differences between parks and cemeteries in Central Europe

Urbanization is a permanent and still continuing expansion of human settlements and is responsible for dramatic changes of natural areas to urban areas. In traditional view, urbanization is often blamed for the loss of biodiversity and biotic homogenization of natural communities. However, for some species, urban areas, can represent suitable environment for life and even enable them to maintain stable and abundant populations. Urban ecosystems are not homogenous; within human settlements we can find several different habitats which can be occupied by species with different tolerance to certain aspects of urban life. This diversity can be exhibited by interhabitat changes in species richness, diversity and abundances of local communities. Here, we investigated biodiversity patterns in bird communities of two urban habitats, parks and cemeteries, in three Central European countries. Data on species richness, diversity and abundances of birds were collected from published papers as well as unpublished sources. Our analyses revealed that bird species richness was positively correlated with area and age of trees in both habitat types. There was however no significant relationship between species diversity and area in both habitat types. Moreover, species composition of bird communities significantly varied between cemeteries and parks with strong preference for one of habitat types in several species. Predominant occupancy of habitat type by certain species could be linked to interhabitat differences in vegetation structure, human behaviour and management. Interestingly, several bird species often recognised as urban avoiders were detected in surveyed cemeteries and parks.     

Tree composition and diversity in relation to urban park history in Hong Kong,China

In densely populated cities that are dominated by concrete buildings, urban parks serve as major green infrastructures for ecological and environmental functions. Trees are one of the important components that support these green infrastructures. Despite plenty of urban parks established in Hong Kong in the last 20 years, knowledge of tree composition and diversity is outdated. There were also no studies that investigated the differences in tree diversity in relation to park history. Therefore, this study aims to identify the temporary changes in tree composition and diversity in Hong Kong, by conducting a plot-based tree survey in 32 urban parks of different ages. Overall, 2801 trees belonging to 181 species were recorded in 319 plots across all the parks. A ridit analysis was conducted and it indicated the mature size of trees were not significantly larger in old parks. However, the linear mixed-effects models and the post-hoc tests suggested that DBH, tree height and the proportion of crown dieback for each class of tree size were greater in the old parks. Moreover, the composition of top-ranking dominant tree species varied substantially, where more ornamental and exotic trees were adopted in new parks. For species richness, the sample-based species accumulation curves of different park age overlapped when the horizontal axis of the curve was scaled by the average number of combined individual trees. When the horizontal axis was scaled by the number of plots, the curve for the old parks was above the curve for the new parks. The differences derived from these two accumulation methods indicated a higher tree density in old parks. For species evenness, both the rank-abundance curves and Rényi diversity curves depicted a similar low species evenness in old and new parks. These results suggested that species diversity remained largely unchanged from old parks to new parks though the dominant tree species varied. Greater attention should be paid to increase the species evenness in all urban parks, increase tree density in new parks and improve tree maintenance in old parks.     

Stress-resistant trees are more common in urban than rural forests: A case study of Cleveland,Ohio’s natural parks

Natural parks are comprised of preserved forested natural areas that are undergoing natural ecological processes. These areas can offer a refuge for local biodiversity and contribute substantially to ecosystem services in both rural areas with relatively low population densities, as well as high-density urban areas. Forested natural parks located in urban areas should experience more stressful environmental conditions than nearby rural areas, yet we know relatively little about how urbanization impacts tree communities within these important natural habitats. To better understand the impact of urbanization on forests, we investigated the species composition, abundance, and diversity of midstory and canopy trees as well as tree seedlings in urban and rural natural parks in and around Cleveland, Ohio. We found that both urban and rural natural parks have similar tree abundance, but midstory and canopy trees as well as tree seedling communities in the urban natural parks included higher abundances of stress-tolerant species compared to rural parks. In addition, this pattern was driven by changes in native tree species, as we observed low abundance of invasive species. More stress-resistant native species in urban areas include Quercus rubra and Prunus serotina, in contrast to rural natural parks which are dominated by Acer spp. and Fagus grandifolia. Lastly, we show that urban and rural natural parks have similar species diversity within plots, but we found higher variation in community composition among urban natural parks compared to among rural parks. Furthermore, Q. rubra and P. serotina were significantly larger in rural natural parks, indicating that both environmental stress and successional stage could drive compositional differences. Thus, we show that urbanization can have unexpected effects on plant community composition and diversity. Our study refutes the idea that these are degraded habitats, highlights the need to conserve them, and suggests that characterization of local variation in self-assembled urban tree communities will provide the most accurate picture of their management needs and potential ecosystem services.     

Assessing the species diversity and vulnerability of urban tree populations in the London borough of Westminster

The level of tree species diversity in urban tree populations can have serious implications for urban forest resilience and has a direct impact on ecosystem functioning at the local level. Few studies have measured the relationship between tree species diversity and vulnerability in UK urban forests. This study analysed the species composition, species diversity and the vulnerability to pests and diseases of 10,149 public trees in the London borough of Westminster across three land use types: housing, parks, and highways. Tree species diversity was significantly different across these land use types (Shannon’s diversity index (H) was 2.47 for housing sites, 1.63 for parks and 0.83 for highways) and we found that higher diversity appears to result in reduced vulnerability, evidenced by negative correlations between tree species diversity and susceptibility to pests and diseases. A stronger negative correlation was found between vulnerability and species richness than between vulnerability and Gini-Simpson’s diversity index. Our study reinforces the role of biodiversity indices in establishing and monitoring baseline levels of UK urban tree diversity. Our findings may inform future tree planting projects, help to ensure that development does not negatively affect urban tree diversity and inform proactive strategies for urban trees to contribute to wider biodiversity conservation.     

Enhancing plant diversity and mitigating BVOC emissions of urban green spaces through the introduction of ornamental tree species

Promoting the plant diversity of urban green spaces is crucial to increase ecosystem services in urban areas. While introducing ornamental plants can enhance the biodiversity of green spaces it risks environmental impacts such as increasing emissions of biogenic volatile organic compounds (BVOCs) that are harmful to air quality and human health. The present study, taking Qingdao City as a case study, evaluated the plant diversity and BVOC emissions of urban green spaces and tried to find out a solution to increase biodiversity while reducing BVOC emissions. Results showed that: (1) the species diversity and phylogenetic diversity of trees in urban green spaces were 22% and 16% lower than rural forest of this region; (2) urban areas had higher BVOC emission intensity (2.6 g C m⁻² yr⁻¹) than their rural surroundings (2.1 g C m⁻² yr⁻¹); (3) introducing the selected 11 tree species will increase 15% and 11% of species diversity and phylogenetic diversity, respectively; and (4) the BVOC emissions from green spaces will more than triple by 2050, but a moderate introduction of the selected low-emitting trees species could reduce 34% of these emissions. The scheme of introducing low-emitting ornamental species leads to a win–win situation and also has implications for the sustainable green space management of other cities.     

Biodiversity functions of urban cemeteries: Evidence from one of the largest Jewish cemeteries in Europe

As the world becomes more urbanized, urban cemeteries may become increasingly valuable for biodiversity conservation as cemeteries are ubiquitous elements of the green infrastructure in cities worldwide. By implementing a multi-taxon approach at different spatial extents, we analyzed habitat functions of a large urban cemetery in Berlin (Weiÿensee Jewish Cemetery) and explored related environmental variables. This cemetery is an outstanding cultural heritage site but it also stands for old urban cemeteries that have progressed to urban woodland, an ecosystem type that exists in many regional and religious contexts. The cemetery provided a habitat for 604 species; species of conservation concern comprised 1.6⿿100% of total species among different groups of taxa (in decreasing order: bats, birds, lichens, bryophytes, carabids, vascular plants, spiders). Species richness and species composition at the plot level were significantly related to differences in management intensity and resulting vegetation structures but differed among taxonomic groups. In vascular plants, carabids and spiders, the species composition varied significantly with habitat age, and there was a set of characteristic species for different age classes in each species group. Our results thus support the use of differentiated management approaches to maintain habitat heterogeneity by allowing wilderness development in some parts of a cemetery while keeping others more open. Since these aims can be combined with efforts to preserve outstanding grave architectures and allow access to visitors, our study indicates ways of reconciling conflicting aims of heritage preservation and biodiversity conservation, a promising perspective for biodiversity conservation in culturally shaped urban landscapes. We conclude that cemeteries provide important cultural ecosystem services within the urban green infrastructure.     

Comparison of bird diversity between temperate floodplain forests and urban parks

Biodiversity in urban green areas has been widely explored in several bird studies because birds are known to be important bio-indicators. Many studies have investigated the different responses of bird communities to urbanization and land use changes in urban environments. However, there are still important knowledge gaps related to the impacts of the heterogeneity, spatial structure, and connectivity of green areas on avian diversity. Such information is needed for sustainable urban planning. In this study, we focused on the comparison of bird communities between urban parks in the heritage city of Olomouc and hardwood floodplain forests in the vicinity of the city. The results of the study indicate the high importance of urban parks for the maintenance of bird diversity even though urban parks are man-made habitats. The results highlight the importance of some native vegetation structures in urban parks (old trees, bush ecotones) for maintaining urban bird biodiversity. Some implications of the results can be widely used as a decision support tool for the management of urban green areas and for the planning of ecological networks in urban landscapes.     

Plant and microbial biodiversity in urban forests and public gardens: Insights for cities’ sustainable development

As the world’s population gets increasingly more urban, the preservation of urban green spaces becomes an important issue in the political agenda worldwide. These spaces may mitigate the negative environmental impacts of urbanisation and improve quality of life. Aiming to increase knowledge in urban biodiversity we compared the diversity of vascular plants and soil microbial communities (fungi and bacteria) in two contrasting typologies of urban green spaces (public gardens and remnant forests) in the city of Coimbra (Portugal). We found 252 taxa of vascular plants of which 58% were native and 42% exotic. Although overall diversity indices were similar in both typologies of green spaces, species richness and percentage cover of native taxa were significantly higher in forests than in gardens. Overall, plant communities in the two typologies of green spaces were distinct. We found high variability among gardens, which is consistent with vegetation in gardens being determined by man rather than by competitive or successional processes. Interestingly, the disparity between gardens and forests was also visible for both bacterial and fungal communities indicating an association between above and below-ground communities. We showed that, due to their origin, remnant forests harbour plant taxa with high conservation and ecological values. It also showed that gardens have higher percentage of exotic species, which led us to conclude that native plant species should be given more emphasis in these spaces. City planners should promote urban development by incorporating an ecological perspective into their management plans to enhance human health and global environmental quality.     

Diversity and distribution of the urban tree population in ten major Nordic cities

In order to have a healthy and sustainable urban tree population, a high diversity of species and genera is needed. This study examined (1) the diversity and distribution of genera and species of urban trees in the Nordic region; (2) the diversity in different sites of the city, distinguishing between street and park environments; and (3) the presence of native versus non-native tree species in urban environments in the Nordic region. The analysis of tree diversity was based on urban tree databases comprising a total of 190 682 trees in 10 Nordic cities – Aarhus and Copenhagen in Denmark; Espoo, Helsinki, Tampere and Turku in Finland; Gothenburg, Malmo and Stockholm in Sweden; and Oslo in Norway. The tree databases for Copenhagen, Espoo, Helsinki, Stockholm and Tampere only record street trees, while the remaining databases also include park trees. Tilia was the most dominant genus in Arhus, Copenhagen, Espoo, Gothenburg, Helsinki, Oslo and Stockholm, while Sorbus was the most dominant in Malmo and Betula in Tampere and Turku. Tilia × europaea was the most common species, comprising 16.0% of the total number of tree species. There was a higher proportion of species in parks than in street environments. The number of non-native species was higher than the number of native species in both street and park environments. However, the number of individuals belonging to native species was higher than the number of non-native individuals in all cities and environments except park environments in Arhus. The concluding recommendation from this study regarding greater diversity of genera and species is to exploit local experiences of rare species from local urban tree databases. After appropriate evaluation, urban tree planners can evaluate these rare species in larger numbers for e.g. street environments, where the need is greatest.     

Relationships between socio-demographic / socio-economic characteristics and neighborhood green space in four Nordic municipalities – results from NORDGREEN

Urban green space governs important ecosystem services including providing health promoting facilities. However, unequal distribution of green space among socio-demographic and socio-economic groups may create environmental injustice among inhabitants and between neighborhoods. This paper reports on access to different types of green space for residents in four Nordic cities. More precisely it explores relationships between socio-demographic and socio-economic characteristics and access to green space at the neighbourhood level. We selected the following green space variables: distance between inhabitants’ dwellings and parks, forest, and cemeteries; percentages and area per inhabitant of parks, forest, and cemeteries; and vegetation cover derived from satellite images and Urban Atlas. These were linked to income, education, age, and percentage of the population born outside their country of residence at a neighbourhood level. The results show that inhabitants in the four Nordic cities have great access to green space, but the percentage of different types of green space, such as forest and parks, varies between the cities and within the cities. We found that most inhabitants have less than 300 m to the nearest green space ranging from 92% in Stavanger (Norway) to 99.2% in Täby (Sweden). We also found differences in access depending on inhabitants' age, education, immigration status, and median income. Espoo (Finland) had the highest total green space coverage (45.3%), while Täby had the highest proportion of park coverage (2.3%). By compensating with green spaces in less affluent areas, and focusing on equal access to green space, planners can contribute to reduce health inequalities in the population.     

Qualities and functions ascribed to urban cemeteries across the capital cities of Scandinavia

Cemeteries are not only burial places that provide a public service. They are also green urban spaces with cultural and natural qualities and could be integrated into the green infrastructure planning system. In this study, we explore the extent to which environmental qualities and functions are ascribed to urban cemeteries in the municipal master plans, green infrastructure plans and websites of the capital cities of Scandinavia. In addition, we conduct a focus-group interview in Oslo with six municipal employees representing green space planning/management, cultural heritage and cemetery administration/management, focusing on a broad perspective of qualities ascribed to urban cemeteries. The document study shows that, across the Scandinavian countries, cemeteries are mainly included in the concept of green infrastructure but they are not ascribed qualities similar to those ascribed to public green spaces; instead, most qualities are related to cultural history. However, Copenhagen municipality has a more inclusive approach, describing the cemeteries as green spaces and inviting people to use them for recreational purposes. The municipality even has a policy document with a strategy on how to combine the primary function of a burial site with new needs for recreational space. In the focus-group interview, cemeteries are described as static places, peaceful and quiet places, green spaces, spaces in which to experience darkness, and places for all (multiple use). There is relatively high agreement among interviewees about the recreational qualities of cemeteries, even though the cemetery administration/management emphasizes several times that its main focus is on accommodating the bereaved and their relatives. In the discussion, we focus on differences between the different Scandinavian countries in the qualities and functions ascribed to cemeteries, and examine potential explanations for why cemeteries are mostly described as green spaces, part of the green infrastructure, but treated as private green spaces in the urban planning context.     

Species diversity of urban forests in China

A good knowledge of species diversity is essential for urban forest planning and management. In this study, we analyzed species diversity of urban forests in China using data synthesized through a systematic review. Our analysis showed that 3740 taxa of woody plants at species level and below have been reported in urban forests in 257 cities. Merging to the species level, there were 2640 species, including 1671 trees, 743 shrubs, and 226 lianas. Salix babylonica L. was the most widely distributed urban tree species in China. Overall, native species accounted for 76.02% of the observed species while the rest were exotic species. Inside cities, parks contained more species than other types of land use. Among cities, composition similarity of urban forests decreased as spatial distances among them increased. Besides, there was a latitudinal pattern in compositional similarity of urban forests in China. The relatively low ratio of the number of woody plant species in urban forests to these naturally distributed in China indicates that there is plenty of room for increasing species diversity of urban forests in China. However, cautions must be taken to avoid increasing compositional similarity of urban forests in China at the same time.     

Characteristics of the urban forests in arctic and near-arctic cities

The urban forest of three arctic and near-arctic cities (Murmansk in Russia, Nuuk in Greenland, and Reykjavik in Iceland) were surveyed to determine tree species composition and structure. Interviews with local authorities were conducted to learn about the history of urban tree planting. The urban forests of all three cities were composed of a limited number of trees and tree species due to abiotic constraints of the arctic and near-arctic environment. These limitations include: low temperature, short growing season, high wind velocity and permafrost. A total of 28 species were observed in the three cities. Only three of these (Alnus incana (L.) Moench, Picea abies (L.) Karst., Betula pubescens Ehrh., and Salix glauca L.) were observed in all three of the cities. Planting designs that created windbreaks for pedestrians were common along streets in Murmansk and Reykjavik. Street trees have not yet been introduced in Nuuk, but trees were found in cemeteries, parks, and on private property. Older portions of cemeteries in all three cities were characterized by trees planted directly on graves. These grave trees were the first trees to be introduced in these cities. Subsequently, ‘trial and error’ was used by local residents to plant trees. Much of these plantings failed. In recent times arboreta were established near all three cities to identify species suited for planting under arctic and near-arctic conditions. Trees identified in these test gardens are now being planted in Murmansk and Reykjavik.