Mapping of urban roadside trees – A case study in the tree register update process in Helsinki City

This case study describes a method for utilizing leaf-off airborne laser scanning (ALS) data for mapping characteristics of urban trees. ALS data were utilized to detect and update all street trees in the tree inventory of the City of Helsinki, Finland. The inventory consists of roughly 20,000 street trees with mean diameter at breast height (DBH) of 24 cm and mean height of 10.6 m. The large number of trees makes the manual updating process very laborious. The automatic mapping procedure presented in this paper detected 88.8% of all trees in the inventory. Tree height was predicted with root mean square error (RMSE) of 1.27 meters and tree DBH with RMSE of 6.9 cm. The presented method provides a practical and cost–effective tool for the mapping of urban tree characteristics. The cost–efficiency was further enhanced because the used ALS data were originally collected for other urban planning purposes.     

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.     

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.

     

Measuring patterns and mechanism of greenway use – A case from Guangzhou,China

In the context of recent studies that have begun to establish a more quantifiable understanding of the use of urban greenways, this paper presents a preliminary investigation into the patterns in which a greenway is used and the mechanism behind the pattern of use of the greenway. Factors of the location, economic situation, environment and social background have been measured and analyzed in the use intensity model to interpret their impact on the use intensity of different sections of a greenway. The results suggest that use of the Waterfront Greenway in Guangzhou is highly impacted by population density, employment density, nearby service provision and the connectivity of the greenway to other parts of the city. In this case, the use intensity model with indicators such as location, economic, environmental and social factors has been shown to be applicable to the evaluation of the use of the greenways. Results from the case study suggest that providing greenways close to the residential zones, employment centers and key public services such as hospitals and schools will increase greenway use. The surrounding network system of a greenway must be carefully considered and designed to improve the linking of the greenway to other parts of the city, to increase the number of potential visitors to the greenway.     

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.     

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.     

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.     

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.     

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.     

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.     

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.     

Residential runoff – The role of spatial density and surface cover,with a case study in the Höjeå river catchment,southern Sweden

Depending on the spatial density of built cover and location within a catchment, residential areas make varying contributions to surface runoff throughout different rainfall events. This study examined these contributions and the associated effect of different surface covers and sustainable drainage systems on runoff generation. The Soil Conservation Service curve number (SCS-CN) method was applied to analyse urban development in the Höjeå river catchment in southern Sweden.The results indicated that identical amounts of surface runoff are generated by low-density residential areas on heavy clay soils and high-density residential areas on sandy soils. However, increasing the density of built-up areas on sandy soils is likely to be more disruptive to the hydrological balance and to generate a greatly increasing difference in runoff as building density and impermeable surface area increase. A similar pattern is likely to occur if rainfall intensity increases. It may therefore be appropriate to apply different planning considerations to residential developments depending on the existing soil group, e.g. conserving existing vegetated surfaces on sandy soil and incorporating permeable paving materials and sub-surface infiltration beds in development on clayey soils. Increased area of impermeable surface cover will increase surface runoff in all residential areas, irrespective of building density, soil group and rainfall intensity. However, adapting a systems approach in combining vegetative structures and permeable paving materials with subsurface infiltration beds can help mitigate the impact of surface runoff, particularly in urban developments on clay-rich soils.     

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...     

A contribution to the study of airborne Citrus pollen in Córdoba,southern Spain

Citrus species, and especially oranges, are widely grown in Córdoba (southern Spain) both as ornamentals (Citrus aurantium) and as cash crops (Citrus sinensis). There has been little research into the incidence of orange-pollen allergy in the local population. Given the abundant presence of orange trees in Córdoba, a study was designed to determine local Citrus pollen counts at human height in areas where these trees are densely planted. Although standard aerobiological studies report negligible airborne Citrus pollen counts, the samplers used are located at greater heights and in open areas; as a result, large Citrus pollen grains are not recorded. It was found that when Hirst-type volumetric samplers were placed on the roof of a building – the recommended position for aerobiological research – airborne Citrus pollen counts were very low. By contrast, portable samplers placed at human breathing height recorded very high counts, reaching around 2000 pollen grains/m³ during the peak day. This finding suggests that greater attention should be paid to the potential negative impact on the local population, given that the sparse research has highlighted the allergenic nature of orange pollen. Citrus pollen could have an adverse local health impact in areas where orange-trees are densely planted, particularly given reported cross-reactivity with other pollen types. However, further aerobiological and clinical research into Citrus pollen is required in order to draw wholly reliable conclusions.     

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.     

Where to construct new urban green spaces to be at the recommended distance from users and to complement existing ones? A study in five cities of northern Portugal

The proximity to urban green spaces (UGS) is important to facilitate their use by citizens, mainly by the most vulnerable groups in society who are usually unable to walk long distances. Furthermore, there are several ecosystem services from which the population can only benefit if UGS are close. In addition to being important to identify areas without a UGS nearby, it is also important to indicate possible locations for a new UGS, thus avoiding wasting resources by overlapping coverage areas or leaving gaps in coverage. It is also important to understand among all possible locations where the construction of a UGS is most needed. The present study aims (i) to identify possible locations for future UGS and order them by construction priority, (ii) to develop and test a methodology for decision-makers and urban planners and (iii) to contribute to increasing and developing UGS in cities. Considering residential areas, the results reveal a deficiency in UGS coverage in all the cities studied, as only 43.86–57.09% of residential areas have a UGS within 300 m. Construction of proposed UGS will lead to a 12.30–26.15% increase in coverage. The proposed methodology needs further improvement, but it can be a valuable tool for urban planners and decision-makers, and can encourage the construction of more UGS.     

An improved micropropagation protocol for the recalcitrant plant Capsicum – a study with ten cultivars of Capsicum spp. (C. annuum,C. chinense,and C. frutescens) collected from diverse geographical regions of India and Mexico

Capsicum spp. is a commercially important crop of the Solanaceae family, well-known for its multipurpose use as a vegetable, spice, medicinal and ornamental plants. The genus Capsicum is a recalcitrant species in terms of in vitro morphogenesis and plant regeneration. An efficient method was developed for multiple shoot regeneration in 10 cultivars of Capsicum collected from diverse geographical regions of India and Mexico. Seeds germinated in vitro on a half-strength Murashige and Skoog (MS) medium supplemented with 3.0 % sucrose. Nodes of the in vitro germinated seedlings were used as explant for micropropagation. The combination of the 6-benzylaminopurine, indole-3-acetic acid, and spermidine was found to be the best for multiple shoot induction. However, the optimum responcse varied accompanied by different cultivers with maximum 8.9 ± 0.52 (Capsi-10) to 15.3 ± 0.69 (Capsi-5) multiple shoot per explant. Depending on the cultivar, multiplied shoots were successfully rooted with maximum 18.4 ± 0.20 (highest for Capsi-9) to 36.8 ± 0.29 (highest for Capsi-5) roots per shoot on half-strength MS medium supplemented with 2.0 mg l^?1 indole-3-butyric acid, 1.0 mg l^?1 α-naphthalene acetic acid, and 1.5 mM spermidine. Finally, the micropropagated plantlets were acclimatized with 40.0–86.7 % survival rate, depending on different cultivars.