High carbon losses from established growing sites delay the carbon sequestration benefits of street tree plantings – A case study in Helsinki,Finland

We assessed the net carbon (C) sequestration dynamics of street tree plantings based on 10 years of measurements at two case study sites each with different tree species in Helsinki, Finland. We assessed C loss from tree soils and tree C accumulation, tested the applicability of pre-existing growth and biomass equations against observations, and estimated the time point for the beginning of net C sequestration for the studied street tree plantings. The tree woody biomass C accumulation in the first 10 years after planting was 18–32 kg per tree. At the same time the C loss from the growth media was at least 170 kg per growth media volume (25 m³) per tree. If this soil C loss was accounted for, the net C sequestration would begin, at best, approximately 30 years after planting. Biomass equations developed for traditional forests predicted more stem biomass and less leaf and branch biomass than measured for the species examined, but total aboveground biomass was generally well predicted.     

Influences on the use of urban green space – A case study in Odense,Denmark

Increasing the use of urban green space has appeared on the political agenda, primarily because increased use is expected to improve the health and well-being of the urban population. Green space is contributing to restoring mental fatigue, serving as a resource for physical activity, reducing mortality and reducing the level of stress.However, knowledge and experience on how to implement this agenda are scarce. In this paper, we use a socio-ecological model as framework when studying influences on the use of respondents’ nearest urban green space in the Danish city of Odense. Data were obtained from a survey sent to 2500 randomly selected adult residents within the central part of the city. We tested the relative importance of different factors on the frequency of use of the nearest urban green space by using a multivariate logistic regression model. The results show that almost half of the respondents did not use their nearest green space the most. Whether or not respondent used their nearest green space most depends primarily on area size, distance to the area and factors that are likely to express a reduced mobility; old age, young children and poor health.If the nearest urban green space also is the most used green space, having a dog is the only factor that significantly increases the frequency of use. Further research is needed to determine what it is that makes people use an area more, if the basic conditions of a reasonable size (>5 ha) within a reasonable distance (<600 m) are fulfilled.     

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.     

Assessment and optimization of green space for urban transformation in resources-based city – A case study of Lengshuijiang city,China

Urbanization in China has changed gradually from production-oriented to consumption-oriented in recent years. Comfort and accessibility of green infrastructures effect the rate of urbanization and transformation. A well designed urban green space system is an essential part of the urbanization process. In this paper, the urban green space of Lengshuijiang city was assessed both qualitatively and quantitatively using data of field survey and high resolution remote sensing. In the study area, green space coverage was 37.14%, green space percentage was 33.45% and per capita park green space was 16.25 m². The high green space coverage suggested that there were ample potentials for further urban transformation. Within a 30 min service radius of existing green space, total service area was 204.49 ha, which accounted for 16.26% of the study area. A high proportion of the green space was made up of urban parks which were unevenly distributed across the study area. A green space optimization strategy, aimed at improving green space quality and accessibility, was proposed. After optimization, total service areas within the 30 min service radius will increase to 492 ha (39.12%), an increase of 22.86%. Our study demonstrated that combining qualitative and quantitative methods is an effective and reliable way for green space assessment and reliable and can be used for urban green space planning and management for small resource-based cities like Lengshuijiang in its process of urban transformation.     

How does forest fragmentation affect tree communities? A critical case study in the biodiversity hotspot of New Caledonia

Context

The biodiversity hotspot for conservation of New Caledonia has facing high levels of forest fragmentation. Remnant forests are critical for biodiversity conservation and can help in understanding how does forest fragmentation affect tree communities.

Objective

Determine the effect of habitat configuration and availability on tree communities.

Methods

We mapped forest in a 60 km² landscape and sampled 93 tree communities in 52 forest fragments following stratified random sampling. At each sampling point, we inventoried all trees with a diameter at breast height ≥10 cm within a radius of 10 m. We then analysed the response of the composition, the structure and the richness of tree communities to the fragment size and isolation, distance from the edge, as well as the topographical position.

Results

Our results showed that the distance from the forest edge was the variable that explained the greatest observed variance in tree assemblages. We observed a decrease in the abundance and richness of animal-dispersed trees as well as a decrease in the abundance of large trees with increasing proximity to forest edges. Near forest edges we found a shift in species composition with a dominance of stress-tolerant pioneer species.

Conclusions

Edge-effects are likely to be the main processes that affect remnant forest tree communities after about a century of forest fragmentation. It results in retrogressive successions at the edges leading to a dominance of stress-tolerant species. The vegetation surrounding fragments should be protected to promote the long process of forest extension and subsequently reduce edge-effects.

     

Does urban gardening increase aesthetic quality of urban areas? A case study from Germany

We tested in two corresponding studies the hypothesis that urban gardening is of visual aesthetic value to the public. With the help of photo-realistic visualizations and a written questionnaire, 109 students and employees of the Karlsruhe University of Education (study 1) and 200 passers-by in the city of Karlsruhe (study 2) were asked about their opinion on different urban gardening scenarios, and attitudes towards urban gardening. Our results indicate that urban gardening can contribute to perceived attractiveness of urban areas, but that not all approaches are perceived as equally positive. While flowerbeds or flower meadows and orderly-managed vegetable plots, in comparison to conventional lawns, increased the aesthetic appeal of urban green space, container gardening approaches, which were often characterized as chaotic, did not. Although flower scenarios were preferred over vegetable scenarios, participants were rather positive about the idea of having more vegetable plots around. Socio-demographic variables had only minor influences on preferences and attitudes. As people were fonder of flowerbeds or flower meadows than of vegetable plots, a mixture of both might be advisable in urban gardening sites. This would also increase overall diversity, which is not only beneficial from an aesthetic, but also from an ecological point of view.     

Impact of urban park’s tree,grass and waterbody on microclimate in hot summer days: A case study of Olympic Park in Beijing,China

Urban heat island (UHI) often cause negative impact and has been linked to heart stroke rate, morality, human comfort, energy consumption and air pollution. Fortunately, urban green spaces have been considered as an effective element to mitigate UHI through their cooling effect. However, further empirical research is necessary in order to efficiently guide the design and planning of urban green space. We observed the impacts of urban park's tree, grass and waterbody on microclimate inside the Olympic park of Beijing during summer days. The results indicated that, on average, the park was 0.48–1.12 °C cooler during the day, as well as increased air humidity 2.39–3.74% and reduced human comfort index 1.02–2.43 to generate more comfortable thermal environment. Urban park's cluster trees with short ground vegetation generated higher cooling effect than single trees, grass and waterbodies; proper irrigation regime enhanced the cooling effect of grasses, even the irrigated grass have similar cooling effect with small waterbody on sunny, windless summer days. Therefore, we advise to increase undergrowth coverage and grass irrigation management in order to take advantage of cooling effect of urban parks.     

Uptake and use of biodiversity offsetting in urban planning – The case of Sweden

Globally, biodiversity offsetting is used to balance negative impacts on biodiversity and ecosystem services caused by exploitation. In Sweden, there is an increasing interest in biodiversity offsetting in urban planning. However, there is limited understanding about the use of the concept in a municipal context. This study aims to examine and critically reflect on the uptake and use of biodiversity offsetting at a strategic level in urban planning in Sweden. We study urban planning documents, and included Sweden’s 290 municipalities in the study. The result shows that more than 50% of Sweden’s municipalities mention biodiversity offsetting in their planning documents, targeting both regulatory offsetting of protected areas and voluntary offsetting of urban green space. The uptake is highest in urban areas experiencing high exploitation pressure, and many municipalities include both biodiversity and ecosystem services in their strategic work with offsetting. Most municipalities do not relate to the mitigation hierarchy (avoid, minimize, restore, offset), nor the goal of no net loss of biodiversity and ecosystem services. There is an ambiguity in the translation between losses and offsets, i.e. what type of offsetting (like-for-(un)like), what replacement ratios, and where to place the offsets. Few municipalities have developed processes, guidelines, strategic plans, etc., to integrate offsetting into the planning process. We conclude that the uptake of biodiversity offsetting is substantial, but with a fragmented, and often immature use in relation to ecological knowledge, and the planning process. We argue that, to develop biodiversity offsetting into an approach that delivers sound outcomes for nature and people in urban planning, municipalities must have a capacity in terms of organisational structures and resources.     

Tree mapping using airborne,terrestrial and mobile laser scanning – A case study in a heterogeneous urban forest

We evaluated the accuracy and efficiency of airborne (ALS), terrestrial (TLS) and mobile laser-scanning (MLS) methods that can be utilized in urban tree mapping and monitoring. In the field, 438 urban trees located in park and forested environments were measured and mapped from our study area located in Seurasaari, Helsinki, Finland. A field reference was collected, using a tree map created manually from TLS data. The tree detection rate and location accuracy were evaluated, using automatic or semiautomatic ALS individual tree detection (ALS_ITDauto or ALS_ITDvisual) and manual or automatic measurements of TLS and MLS (TLS_auto, MLS_auto, MLS_manual, MLS_semi). Our results showed that the best methods for tree detection were TLS_auto and MLS_manual, which detected 73.29% and 79.22% of the reference trees, respectively. The location accuracies (RMSE) varied between 0.44 m and 1.57 m; the methods listed from the most accurate to most inaccurate were MLS_semi, TLS_auto, MLS_manual, MLS_auto, ALS_ITDauto and ALS_ITDvisual. We conclude that the accuracies of TLS and ALS were applicable for operational urban tree mapping in heterogeneous park forests. MLS_manual shows high potential but manual measurements are not feasible in operational tree mapping. Challenges that should be solved in further studies include ALS_ITDauto oversegmentation as well as MLS_auto processing methodologies and data collection for tree detection.     

A socio-ecological exploration of fear of crime in urban green spaces – A systematic review

Studies have pointed at the negative side of urban green spaces in terms of evoking fear of crime. However research on fear-provoking attributes suggests that there usually is no single attribute that influences fear but that rather a combination of attributes prevails. The aim of the paper is to systematically review those attributes that evoke fear of crime in urban green spaces and to highlight their complex interaction by adopting a social-ecological framework. Results include an overview of the reviewed literature with regard to authorship, journal, geographical distribution of the studies, types of urban green spaces studies, types of landscape stimulus used, applied methods, types of respondents involved and main study findings. Forty-eight studies met the authors’ inclusion criteria. The majority of the studies highlighted that individual factors (such as gender and past experience) were more influential than social and physical factors in evoking fear of crime. A proposed socio-ecological framework highlights the attributes which evoke fear of crime in urban green spaces and its interactions and can help guide future research.     

Dispersal limitation at the expanding range margin of an evergreen tree in urban habitats?

Dispersal limitations contribute to shaping plant distribution patterns and thus are significant for biodiversity conservation and urban ecology. In fleshy-fruited plants, for example, any preference of frugivorous birds affects dispersal capacities of certain fruit species. We conducted a removal experiment with fruits of Ilex aquifolium, a species that is currently expanding its range margin in northern Europe in response to climate change. The species is also a popular ornamental tree and naturalization has been observed in many parts of its range. Fruits of native I. aquifolium and of three cultivars were offered to birds at the expanding range margin in urban habitats in eastern Denmark. The four fruit types were removed at different rates and red fruits were preferred over a yellow cultivar. Small fruit diameter was positively related to fruit removal, and removal was faster under tree canopies compared with open habitats. The preference for red cultivars compared with native I. aquifolium may contribute to naturalization and potential invasion of garden escapes. Preferential foraging under closed canopies indicates trees and shrubs as recruitment foci for fleshy-fruited plants in urban landscapes. The results should be included in urban forestry and planting of potentially invasive ornamental species.     

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

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

How does enclosed private residential green space impact accessibility equity in urban regions? A case study in Shenzhen,China

Compared with public parks, residential quarter green space (RQGS) is a type of enclosed private green space that is located in residential areas and has higher visit frequency. Generally, in China residential areas with high housing prices have higher quality and more quantity of RQGS. Therefore, the differences in RQGS between residents with different socio-economic status may influence the equity of urban green space accessibility. However, due to the lack of data sources, few existing studies have taken RQGS into account as a part of urban green space supply resources. Based on multi-source geographic big data, this paper takes Shenzhen as the research area to explore the impact of RQGS on the spatial pattern and fair distribution of green space accessibility. The total green space accessibility (TGSA), which includes the accessibility of RQGS, and the public park accessibility (PPA) were calculated using the Gaussian-based two-step floating catchment area method (2SFCA). Using housing prices to indicate the income level of dwellers, bivariate Moran’s I and multiple regression were adopted to explore equity of urban green space accessibility. The main conclusions were: (1) The accessibility of green space increased by 27.97% on average after considering RQGS and ignoring RQGS could underestimate the accessibility of green space, particularly in the residential quarter with high housing prices near the city center. (2) The regression coefficients of housing prices with PPA and TGSA were 0.042 (p < 0.01) and 0.160 (p < 0.001), respectively, indicating that the advantages of high-income groups in RQGS may further exacerbate the inequity of urban green space accessibility. The research conclusions may provide a scientific basis for optimizing the spatial structure of green space in urban areas and ensuring the equitable distribution of green space.     

Transforming the economic value of hillside housing—A case study of Seoul,South Korea

This study examines transforming real estate value of urban hillside for residential developments, drawing on two-fold panel analyses: a random-effect panel modeling and a growth-curve panel modeling, in Seoul, South Korea from 1990 to 2015. The results reveal the reduced gap between the land values in hillside and low-lying residential sites as moving toward 2015, evidenced by the rapidly growing rate of increase of land value in the former, whereby the parabolic curvature of the land value trajectory increased from 0.00152 to 0.00156, compared to that of the latter, whereby the equivalent to that decreased from 0.00224 to 0.00214. The results also suggest that the negative effect of higher elevation has decreased to approximately zero (−0.625% per 10-m increment) and projected to turn positive, in hillside residential sites, while the equivalent to that in the low-lying residential sites has been exacerbated (−3.786% per 10-m increment). By helping the understanding of the past, current and future hillside housing development—how the hillside sites have been and will be reevaluated by passage of time, this study will provide practical lessons in planning urban housing and natural amenity resources.     

Does manipulation of fruit-tree architecture affect the development of pests and pathogens? A case study in an organic apple orchard

Summary

Centrifugal training, based on the extinction procedure, is an innovative type of apple tree training recently used in French apple orchards. A thinning cut of fruiting spurs along the trunk and on the proximal and underside parts of the fruiting branches modifies the within-tree leaf density and light environment, which is likely to affect the development of some apple pests and pathogens. In this study, development of the most serious foliar pests (aphids, mites) and disease (apple scab) was assessed over 3 years in an organic apple orchard with two training systems: the centrifugal training (CT) system, and the Original Solaxe (OS) system, using a bent axis with no removal of fruiting spurs, as a control. Infestation levels were significantly lower in 2002 and 2004 in the CT system than in the OS system for the most prevalent pest, the rosy apple aphid, Dysaphis plantaginea and, in 2003, for the red spider mite, Panonychus ulmi. Infestation by the green apple aphid, Aphis pomi, was higher in June 2002 and 2004 and lower in June 2003 in the CT system, compared to the OS control. The incidence of apple leaf scab was lower in the CT system than in the OS control in Spring 2002 and Spring 2004; but, later in the Summer, it increased more in CT trees, resulting in no difference between training systems in the levels of fruit infection at harvest. Hypotheses considered were based mainly on: (i) the removal of pests or inoculum due to the thinning cut of fruiting spurs for CT trees; (ii) effects on within-tree microclimate, providing a more aerated canopy in the CT system; (iii) shoot density and distribution, allowing greater distances between growing shoots in CT trees; and/or (iv) the shoot growth dynamics, allowing the presence of attractive or susceptible leaves in late June. Since the most serious apple pests and diseases were less prevalent in the CT system over the 3 years of the experiment, CT may prove to be a complementary, sustainable means to contribute to crop protection, especially in organic or integrated pest management orchards.     

Mapping ecoregions under climate change: a case study from the biological ‘crossroads’ of three continents,Turkey

Landscape Ecology - Besides climate change vulnerability, most ecosystems are under threat from a history of improper land-use and conservation policies, yet there is little existing long-term...     

Is ecosystem service research used by decision-makers? A case study of the Murray-Darling Basin,Australia

This paper investigates the accessibility and usefulness of the Ecosystem Services (ES) framework to policy analysts. Using a mixed methods approach of document analysis and semi-structured interviews we examine how an ES assessment of the benefits of restoring water to the Murray-Darling Basin (MDB) in Australia has been used by government agencies in policy and planning. The ES assessment links changes in water management under the Basin Plan with modelled changes in water quality, river flows and inundation patterns and in turn to modelled freshwater and estuarine ecosystem response. These ecological responses were expressed in terms of incremental ES benefits which were valued monetarily using a variety of valuation techniques. To investigate how these pieces of information were used in the policy debate around the re-allocation of water in the MDB, semi-structured interviews were conducted with 20 Australian, State, and local government officials as well as academics and consultants. The interviews were designed to uncover the complex information dissemination process through networks within and among agencies. The results are mixed as to whether the assessment served to influence public policy. The report has been utilized and cited by Australian federal agencies, the downstream State of South Australia and conservation-based NGOs in their position statements and as such has been used as evidence in support of re-allocation of water in the MDB. A number of interview participants commented that the ES assessment raised awareness and this may lead to broader usage of the information and framework in the implementation phase of MDB water reform.