Is there a relationship between socio-economic factors and biodiversity in urban ponds? A study in the city of Stockholm

Urban small water bodies, such as ponds, are essential elements of human socio-economic landscapes. Ponds also provide important habitats for species that would otherwise not survive in the urban environment. Knowledge on the biodiversity of urban ponds and the relationship between their ecological value and factors linked to urbanization and socio-economic status is crucial for decisions on where and how to establish and manage ponds in cities to deliver maximum biodiversity benefits. Our study investigates if the pattern of urban-pond biodiversity can be related to different socio-economic factors, such as level of wealth, education or percentage of buildings of different types. Because of lack of previous studies investigating that, our study is of exploratory character and many different variables are used. We found that the biodiversity of aquatic insects was significantly negatively associated with urbanisation variables such as amount of buildings and number of residents living around ponds. This relationship did not differ depending on the spatial scale of our investigation. In contrast, we did not find a significant relationship with variables representing socio-economic status, such as education level and wealth of people. This latter result suggests that the socio-economic status of residents does not lead to any particular effect in terms of the management and function of ponds that would affect biodiversity. However, there is a need for a finer-scale investigation of the different potential mechanism in which residents in areas with differing socio-economic status could indirectly influence ponds.     

Differential community and the perception of urban green spaces and their contents in the megacity of Karachi, Pakistan

Urban green spaces (UGS) denote the chief representative of biodiversity and provider of ecosystem services (especially social and cultural) in urban landscapes. Socio-economic circumstances of individuals are significantly derived from their psychometric settings–which ultimately affect their preferences in urban landscapes–more so for multicultural and multifaceted social environments. This paper investigates the coupling of distinct socio-economic (life quality) standards and urban natural spaces (and their content) in the megacity of Karachi, Pakistan. The main research question was how the socio-economic conditions of the differentiated and multicultural community influence their preferences of urban green spaces. It was tested at three systematically selected research sites of distinct structural and functional characteristics but the results and discussion are presented in an integrative form. The study sites were selected using Karachi’s urban-rural gradient to deduce representative samples from different land use and urbanization zones. Public interviews of 340 respondents were conducted with a structured questionnaire. The findings contradict generalizations made in other international studies. Results show that the presumption of tightly coupled social settings and nature space preferences could not be validated empirically for varying types of cities in the world. This is because people perceive their heterogeneous natural and artificial environment differently in different regional settings. The multicultural environment dissembles the choices of people and vice versa. This is true regardless of the sampling strategy for such studies that had been the focus in the past. Community revitalization is deemed necessary for better design, facilities and functions of UGS to foster social wellbeing of residents as well as sustainable urban development.     

Birds biodiversity in urban and periurban forests: environmental determinants at local and landscape scales

A significant decline in biodiversity is associated with the current and upcoming degree of urbanization. A challenging strategy to address this conflict is to make urban growth compatible with biodiversity protection and in this context urban parks can play a crucial role. Urban systems are highly dynamic and complex human-shaped ecosystems, where the relationship between species and environment may be altered and make the preservation of biodiversity within them a challenging goal. In this study, we analysed how different environmental features affect bird biodiversity in one of the most urbanized areas of Italy (the metropolitan area of Milan) at different spatial scales. Bird surveys were conducted in fifteen urban and peri-urban parks and environmental variables at landscape and local scale recorded. Results showed that a mixture of land covers and the presence of water bodies inside urban parks favoured species occurrence and abundance at landscape scale, but a surrounding dense urban matrix deflated biodiversity. At local scale, woodland cover and presence of water bodies were key determinants in ensuring overall high biodiversity but local-specific vegetation management produced an unusual pattern for forests species. In particular, the maintenance of large trees may not result in biodiversity support for forest bird species if large trees are not located in woodland areas with a significant tree density. To understand biodiversity patterns and provide useful information for urban planning and design, we need to provide insights into species/environment relationships at multiple scales in the urban environment.     

Effects of biodiversity and environment-related attitude on perception of urban green space

Green space in cities contributes to the quality of life for city dwellers, e.g., by increasing the opportunity for recreation. However, perception of urban green space is influenced by multiple factors. We investigated effects of biodiversity and environment-related attitudes on visual and auditory perceptions of urban green space. Field measurements of biodiversity were conducted in six sites across an urban gradient in Gothenburg, Sweden, and three categories of biodiversity—high, medium, low—were established. Households were sent a survey on aesthetic perception of urban green space, sound perception and the importance of trees and plants for the perception of bird species. Each respondent focused on the site that was located nearby. The environment-related attitudes comprised “Nature-oriented” and “Urban-oriented” persons and were based on participants’ own attitude estimations. It was shown that participants’ “subjective” aesthetic and sound-related perception of urban greenery were in line with the “objectively” measured subdivisions of high, medium and low biodiversity. So also were their estimations of the importance of trees and plants for perception of bird species in urban greenery, although differing only between high and medium/low biodiversity conditions. Persons rating themselves as highly nature-oriented were shown to give higher scores to urban green space aesthetics and to value greenery-related sounds higher, and to attach greater importance to trees and plants in their perception of bird species in urban greenery, than less nature-oriented persons. Highly urban-oriented persons compared to less urban-oriented persons did the same, but only regarding urban greenery-related aesthetics and sounds of nature. We conclude that environment-related attitudes influence perceptions of green space. Moreover, our findings support the idea that biodiversity per se also influences perceptions; people value green space significantly more with high than with low measured biodiversity. Urban planning needs to provide city inhabitants with green spaces that are species-rich, lush, varied and rich with natural sounds.     

How do people perceive urban trees? Assessing likes and dislikes in relation to the trees of a city

Cities are systems that include natural and human-created components. When a city grows without proper planning, it tends to have low environmental quality. If improving environmental quality is intended, people’s opinion should be taken into account for a better acceptance of urban management decisions. In this study, we assessed people’s perception of trees by conducting a survey with a controlled sample of citizens from the city of Morelia (west-central Mexico). Citizens liked both native and exotic tree species and rejected mainly exotic ones. Preference for trees were related to tree attributes; such as size. Trees that dropped leaves or tended to fall were not liked. The most-mentioned tree-related benefits were oxygen supply and shade; the most mentioned tree-related damages were accidents and infrastructure damage. The majority of respondents preferred trees near houses to increase tree density. Also, most respondents preferred trees in green areas as well as close to their houses, as they consider that trees provide oxygen. The majority of the respondents thought more trees were needed in the city. In general, our results show that although people perceive that trees in urban areas can cause damages, they often show more interest for the benefits related to trees and consider there should be more trees in cities. We strongly suggest the development of studies that broaden our knowledge of citizen preferences in relation to urban vegetation, and that further policy making takes their perception into account when considering creating new urban green areas, regardless of their type or size.     

Forest structure and anthropogenic disturbances regulate plant invasion in urban forests

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.

     

Tree diversity,distribution, history and change in urban parks: studies in Bangalore,India

Urban parks constitute critical biodiversity hotspots in crowded, concrete-dominated city environments. Despite the importance, they remain little researched. This paper assesses the biodiversity and distribution of trees in urban parks in the southern Indian city of Bangalore. 127 plots were used to survey tree distribution in parks across the city. The distribution is largely dominated by a few common species. The proportion of exotic species was very high, with 77% of trees belonging to introduced species. Park history had an impact on distribution. Old parks had fewer but larger trees, and greater species diversity compared to recently established parks. Old parks also differed in species composition, having a greater proportion of large canopy trees compared to young parks. Examination of size distributions revealed that large canopied species were gradually being phased out, and replaced by narrow and medium sized tree species which are easier to maintain, but which may not provide the same environmental and ecological benefits. Greater attention requires to be paid to the selection of trees in cities, not just with a view to easy maintenance as is currently the case, but to select an appropriate mix of trees that supports biodiversity and maximizes environmental and ecosystem services.     

Influences of landscape and lifestyle on home energy consumption

Rapid urbanization coupled with concerns about global climate change has renewed interest in energy conservation and carbon dioxide emissions reduction. Urban residential energy consumption is a valuable place to start reducing emissions, and urban tree planting programs have been both proposed and utilized as an energy conservation mechanism. Home energy savings associated with urban trees are often quantified using models because of the many complex interactions among variables that can influence home energy use. However, recent empirical analyses have found that energy savings associated with trees may be minimal relative to other important factors like building characteristics and human behaviors. We surveyed 176 residents from four neighborhoods in Raleigh, NC with varying socio-economic characteristics to assess relationships between summer energy usage, tree cover, homeowner behavior, and building characteristics. As hypothesized, we found that building characteristics, demographics, and human behaviors were all significant variables in describing the variability in summertime home energy usage. Although, total percent tree cover 18?m around the home did not affect summertime energy use, the number of trees in the NE and NW quadrants around each household did predict home energy use. These results indicate that planting trees may not be a successful strategy for reducing energy use from the residential sector in the heavily forested Southeast; rather efforts should target conservation and efficiency.     

How to improve urban greenspace for woodland birds: site and local-scale determinants of bird species richness

Wooded habitats represent hotspots of urban biodiversity, however, urban development imposes pressure on biota in these refuges. Identification of the most influential habitat attributes and the role of local urban characteristics is crucial for proper decisions on management practices supporting biodiversity. We aimed to identify well manageable fine-scale habitat attributes to suggest specific, feasible and affordable management recommendations for green space in cities. We analysed species richness of woodland-associated bird communities and incidence of individual species at 290 sites in a wide variety of green areas scattered across the city of Prague, Czech Republic. Generalized linear mixed models (GLMM) and regression tree analyses were used to identify site-scale (100 m radius sampling sites) and local-scale (200 m and 500 m radius plots) habitat attributes shaping the bird communities at individual sites. Logistic regression was used to assess the responses of individual species to habitat characteristics. Our results imply that at the site scale, management practices should focus on maintenance and promoting species-diverse and older tree stands, with a mixture of coniferous and deciduous trees. Water-bodies and accompanying riparian habitats should be maintained and carefully managed to preserve high-quality remnants of natural vegetation. Presence of a few old trees (about 12 % of tree cover with DBH?>?50 cm) or small urban standing water and watercourses enrich the bird community by at least two species. Species richness of woodland avifauna at particular sites is further supported by the total amount of tree cover in the surroundings, including scattered greenery of public spaces and private gardens. We conclude that proper management at site scale has the potential to increase biodiversity of the urban environment.     

Does education influence wildlife friendly landscaping preferences?

In sprawling metropolitan areas, residential landscaping is a major concern with respect to biodiversity conservation, and it could play a critical role in conserving wildlife habitat. In the United States, residential landscaping typically consists of maintained lawns with specimen plantings of non-native trees and shrubs; such designs provide poor habitat for urban wildlife species. We conducted a case study of Raleigh, North Carolina residents to determine how providing information about the benefits of native plant landscaping to bird species influenced urban residents’ landscaping preferences. We used Wilcoxon Signed Rank tests to determine if respondent preferences for 0, 50, 75 and 100 % native plant landscaping coverages changed after residents were informed about the benefits that native plants provide for birds. Initially, the 50 % native landscaping coverage was most preferred by residents; however, preferences for all four native plant landscaping coverage designs were significantly different after the informational treatment. Neutrality changed to opposition for the 0 % native plant coverage, while opposition changed to support and neutrality for the 75 and 100 % native plant coverage designs, respectively. After the informational treatment, the 50 and 75 % native plant landscaping coverage had the highest mean preference levels, although the 100 % design was ranked first more than any other design. Our findings suggest that residential support for native plant landscaping is higher than is reflected by typical residential landscaping practices, and that dissemination of information regarding the benefits of native plant landscaping to birds could alter public preferences for native plant landscaping.     

Investigations of the urban street tree forest of Mendoza, Argentina

The investigation of the urban street trees was undertaken in the oasis city Mendoza, Argentina. The analysis included 1,680 urban street trees in their structure (species, age, and spatial structure), vitality and irrigation conditions. A questioning of 120 residents analysed the perception and acceptance of the urban trees by urban dwellers. Different urban structures, residential, commercial and residential mixed structures and the city centre were investigated. The results show clearly the insufficient maintenance of the trees (composition, aging, irrigation, pruning etc.) and damaged irrigation system with leads to a loss of vitality. The questioning showed that easily recognisable problems (insufficient pruning etc.) are more reflected by people than long term problems (irrigation). There is a different reflection of urban street tree problems in the different urban areas, related to status, information level and management. The maintenance and relation to urban street trees was best in the residential area. Not only better maintenance of the trees but also a clearer recognition of street tree problems by residents and by the responsible municipal institutions is urgently needed. A public-private partnership and more environmental education could help to overcome the problems.     

Urban forest and environmental inequality in Campos dos Goytacazes,Rio de Janeiro,Brazil

Social and spatial inequality regarding environmental resources and services is one of most complex issues affecting contemporary urban life. The objective of this research is to study the spatial distribution of trees in public areas in Campos dos Goytacazes, Rio de Janeiro, Brazil. This research presents data gathered in ten neighborhoods in Campos. These neighborhoods were split into three distinct groups using wealth levels. Data obtained include the number of trees and private gardens and tree species diversity per neighborhood street. Our results demonstrate that the wealthier neighborhoods have both the highest tree biodiversity and number of trees. In contrast, the poorer neighborhoods present a low biodiversity level and fewer tree species. Our results also showed that age of the neighborhoods was not a factor in explaining the number of trees in public spaces. Socioeconomic and education levels of the population seem to play a more causal on tree quantity and species diversity. This inequality stresses a problem with environmental justice, a characteristic of Brazilian cities intrinsically connected to urban sustainability.     

What shapes plant and animal diversity on urban golf courses?

Recent concern over increasing loss of biodiversity has prompted considerable interest in the role of urban green spaces as reservoirs of local biodiversity. This study assessed the diversity of three indicator taxa - plants, ants and birds - on golf courses spanning a wide range of environmental variation in terms of climate, elevation, course age, size and connectivity to native woodland. Species richness and community composition was further compared between contrasting on-course habitat types that reflect different management intensities. We identified a set of taxon-specific environmental correlates indicating an intricate interplay of landscape- and local-scale variables that affect local species diversity. Our results show that floristic diversity is positively associated with the amount of rainfall, whereas ant and bird diversity are related to local-scale factors, particularly the number of trees and the size of water features on a site. The amount of on-course native habitat was a strong predictor of plant and ant diversity and was also associated with the number of unique species at the site level; this reinforces the value of remnant habitat patches as local biodiversity reservoirs that represent mini hot-spots in an otherwise species-poor urban landscape. Community composition for all three taxa differed markedly between non-playing and playing areas, with boundary and remnant habitats generally having more diverse, species-rich communities. Our results suggest that local floral and faunal biodiversity on urban golf courses can be enhanced by creating woody non-playing areas and, especially, by preserving, restoring or expanding remnant habitats.     

Determinants of urban tree canopy in residential neighborhoods: Household characteristics, urban form, and the geophysical landscape

The aesthetic, economic, and environmental benefits of urban trees are well recognized. Previous research has focused on understanding how a variety of social and environmental factors are related to urban vegetation. The aim is often to provide planners with information that will improve residential neighborhood design, or guide tree planting campaigns encouraging the cultivation of urban trees. In this paper we examine a broad range of factors we hypothesize are correlated to urban tree canopy heterogeneity in Salt Lake County, Utah. We use a multi-model inference approach to evaluate the relative contribution of these factors to observed heterogeneity in urban tree canopy cover, and discuss the implications of our analysis. An important contribution of this work is an explicit attempt to account for the confounding effect of neighborhood age in understanding the relationship between human and environmental factors, and urban tree canopy. We use regression analysis with interaction terms to assess the effects of 15 human and environmental variables on tree canopy abundance while holding neighborhood age constant. We demonstrate that neighborhood age is an influential covariate that affects how the human and environmental factors relate to the abundance of neighborhood tree canopy. For example, we demonstrate that in new neighborhoods a positive relationship exists between street density and residential tree canopy, but the relationship diminishes as the neighborhood ages. We conclude that to better understand the determinants of urban tree canopy in residential areas it is important to consider both human and environmental factors while accounting for neighborhood age.     

Urbanization decreases the extent and variety of leaf herbivory for native canopy tree species Quercus rubra,Quercus alba,and Acer saccharum

Urban Ecosystems - The extent to which urban trees can support associated biodiversity and provide ecosystem services depends on how urbanization affects the relationship between plants and the...     

Correlation between the geometrical characteristics of streets and morphological features of trees for the formation of tree lines in the urban design of the city of Orestiada,Greece

This paper classifies the streets of the city of Orestiada, Greece, and examines the correlation between the geometric characteristics of streets and the appropriate height of trees that form the street tree lines so that the microclimate in each street may be improved. The rows of trees improve the aesthetic quality of the urban spaces, and also strengthen the sense of enclosure through tree planting, especially in monotonous urban landscapes. Our main aim is to augment the vegetation in urban areas to achieve the greatest shading of streets in order to contribute to the improvement of the urban environment in terms of bioclimatic conditions. The methodology used in this paper aims to promote the use of trees in urban design, and to evaluate the effects of shading at the city scale with regard to microclimate and energy saving, and to develop tree selection and design guidelines for recommended planting programs. It is expected that the results of the study will be useful to Urban Planners, Urban Arboriculturists, Urban Foresters and Landscape Architects that are engaged in the design and construction of streetscapes in Mediterranean region.     

A systematic review of the relationship between urban agriculture and biodiversity

Urban agriculture is a unique form of agriculture that can provide fresh, local produce for urban residents, and may benefit biodiversity by decreasing the need to expand agriculture into natural areas as well as enhancing biodiversity in urban areas. However, although urban agriculture is also often cited as promoting biodiversity in urban areas, the extent of empirical evidence for such claims has not been studied. Here we systematically review the relationship between urban agriculture and biodiversity in the scientific literature. We strictly define urban agriculture as areas in cities that grow produce specifically for human consumption. We examined 148 papers from 2000 to 2017, of which only 24 studies fit our definition of urban agriculture, and of those, only 18 both involved urban agriculture and measured biodiversity. Of the studies that did measure biodiversity, some showed increases in diversity compared to urban vacant lots, but other showed no difference. Moreover, these studies were mostly focused on plants and invertebrates and were conducted almost exclusively in North America. In order to use the generalization that urban agriculture will have a positive influence on urban biodiversity, more studies will need to be conducted across a wider geographic range worldwide (particularly in developing countries in the tropics) and on a greater diversity of species and taxa (e.g., herpetiles, birds and small mammals). Such studies will likely increase in conservation importance as urban expansion and agricultural demands increase globally.     

Non-native plants are a seasonal pollen source for native honeybees in suburban ecosystems

In urban and suburban ecosystems, biodiversity can depend on various non-native plant species, including crop plants, garden plants and weeds. Non-native plants may help to maintain biodiversity by providing a source of forage for pollinators in these ecosystems. However, the contribution of plants in urban and agricultural areas to ecosystem services has often been underestimated in biodiversity assessments. In this study, we investigated the pollen sources of native honeybees (Apis cerana) in an arboretum containing native trees and urban and agricultural plants in a suburban landscape. We surveyed the flowering tree species planted inside the arboretum, which were potential pollen sources. The number of potential pollen-source species of native trees peaked in June and July and decreased after August. We collected A. cerana pollen balls every month and identified plant species of pollen in the collected pollen balls using DNA barcoding. In total, we identified 29 plant species from A. cerana pollen balls. The probability of A. cerana using pollen from urban and agricultural plants was higher in July and August than in June. A. cerana collected pollen forages from native tree species (53%), but also gathered pollen from crop plants (13%), garden trees (19%) and native and non-native weeds (14%); the predominant pollen sources in September and October were the garden tree Ulmus parvifolia and the non-native weed Solidago altissima. We found that native honeybees used plants from a variety of habitats including non-native plants to compensate for apparent seasonal shortages of native tree sources in suburban ecosystems. Our results highlight the importance of assessments of both positive and negative roles of non-native plants in urbanized ecosystems to improve biodiversity conservation.