Browsing by Subject "Urban Ecology"

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  • Latus, Jessica (Helsingfors universitet, 2014)
    Urbanization is occurring at rapid rates worldwide. While the effects of urbanization are numerous, those on wildlife are of utmost concern in the continued fight for biodiversity conservation. Specifically, the focus on global pollinator declines is of interest due to the interconnectedness between pollinators and plant communities. It is feared that urban areas could become dead zones to these species, specifically bumblebees. Bumblebees are one of the native pollinators of Finland, and therefore were the focus of this study, which was conducted in Helsinki (southern Finland). This project's focus was on the influence of both local (i.e. flowering resources) and landscape (i.e. levels of urbanization) features on bumblebee communities. More specifically, I was interested in the effects of urbanization on bumblebee abundance and species richness. To study this question, community gardens (allotment gardens) were used as study sites along a gradient of urbanization from low to high (chosen by GIS mapping of the levels of impervious surfaces within 500 m of the sites). It is thought that these greenspaces could function as habitat for bumblebees in cities. This study was conducted during the summer of 2013 in 12 community gardens across the city of Helsinki. Two methods to survey bee populations were utilized, pan traps as well as sweep netting. Furthermore, a vegetation analysis was conducted to assess the level of resources present within the gardens, while GIS was used to measure a set of landscape variables in and around each garden. At the end of the season (June to September) the bees were identified and Generalized Linear Mixed Effects models were used to analyze the data. This study found that local variables more strongly predicted both bee abundance and species richness. Even though landscape variables were not strong predictors, this does not make them irrelevant in future conservation strategies. However, it is thought that as long as community gardens are planted appropriately (i.e. native flowers) the bees will be present in these gardens despite the surrounding matrix of inhospitable land (sealed surfaces). In conjunction with the investigation into the effects of local versus landscape determinants, this study also aimed to investigate the perception of gardeners towards bees. A questionnaire was utilized in order to gauge gardeners' opinions towards the bees in their plot and the garden as a whole. These results helped to evaluate the overall attitude towards bees, and in short, were very favorable. This extrapolates to a possibility of working in conjunction with gardeners to conserve habitat for pollinators in the continued effort for interconnected greenspaces in urban areas.
  • Tsui, Ka Man (Helsingfors universitet, 2015)
    Forest certification has been used as a tool to promote forestry responsibility towards sustainable forest management. Forest Stewardship Council (FSC) is one of the certification systems that is well recognised in Europe. Nevertheless, compared to other European countries, the number of FSC chain of custody (CoC) certifications in Finland is relatively low. Semi-structured interviews were conducted with six FSC CoC certified companies to explore their experiences towards implementing and maintaining the system in their companies. The sample group was comprised of wood and paper product industries in manufacturing and trading sectors. Thematic analysis of the interviews revealed the challenges companies encountered. The results indicated that there were eight types of challenges, including three internal and five external ones, hindering the development of FSC CoC certification in Finland. Internal challenges included competence, financial resources, and a lack of motivation to change. External challenges included insufficient marketing and demand, uncertain cost benefit, keen competitor programmes, limited supply, and long trademark approval time. Meanwhile, the relevant solutions these companies adopted to deal with the challenges were discussed. Since external challenges out-numbered internal ones, it seemed that certified companies are not able to tackle the existing challenges alone. Joint-effort among other actors in the forestry sector, for instance, the national authority, FSC national office, certification bodies are essential to influence the rate of certification uptake. Furthermore, participants discussed about the future development of FSC CoC certification system in Finland. Interviewees believed that the enactment of the EU Timber Regulation (EUTR) and the introduction of forest certification into national public procurement policy could positively impact the development of the system. The results of this study could be used as a reference for potential certificate users to prepare themselves for implementing FSC CoC certification system. In addition, the study could shed a light on the development of FSC in Finland in the future.
  • Gelman, Valeria (Helsingfors universitet, 2014)
    The increased rates of population growth and urbanization worldwide raises the question of food security and self-reliance in cities. In view of this situation, in recent years there has been a re-emergence of urban agriculture in its traditional form and in new variations, such as on urban rooftops. A number of rooftop urban farms exist in the world; however, very few studies have been done to establish the quality of crops they produce, specifically concerning the concentrations of contaminants. The main purpose of this study was to investigate levels of contamination in edible plants grown on urban rooftops. I determined concentrations of polycyclic aromatic hydrocarbons (PAH) and trace metals in the biomass of three types of horticultural crops grown in the city of Helsinki, Finland. Lettuce, radish and peas were planted on five rooftops in various areas of Helsinki and control samples were acquired from local food stores and markets. Both groups of crops were analyzed for concentrations of 11 trace elements using the Elan 6000 ICP-MS and 16 PAHs using Shimadzu GC-MS-QP2010 Ultra system with the AOC-20i /AOC-20s autosampler. Additionally, lettuce and pea samples from the roofs were analyzed washed and unwashed to establish levels of particulate contamination on the surface of plants that can be mechanically removed through washing. Results obtained suggest that concentrations of PAHs and trace metals in rooftop vegetables in Helsinki are very low and the differences in their concentrations compared to control (store) samples are insignificant. This demonstrates that the consumption of vegetables produced in uncontaminated soil on urban roofs in Helsinki is safe. All samples showed concentrations well below the safety limits for heavy metals and PAHs established in the European Union (EC, 2006). Finally, there was a difference in concentration of PAHs and trace metals between washed and unwashed samples, however most of the results did not show statistical significance.
  • Liao, Wenfei (Helsingfors universitet, 2017)
    Urbanisation has caused many environmental problems, such as air pollution and the loss of biodiversity. One way to mitigate these problems is to expand green spaces. Roofs, as the last frontier, could be made full use of. Green roofs have become a hot topic in recent years. In this study, I investigated the ability of green roofs to support urban biodiversity by conducting a literature review, and then I sought the criteria for biodiversity roofs under Finnish conditions by interviewing ecologists. My research questions in this study were 1) What kinds of habitats could be 'ideal ecosystems' to be mimicked on biodiversity roofs in Finland; 2) which plant species could exist on roofs and whether they contribute to biodiversity; 3) what kinds of substrates support the biodiversity on roofs; 4) whether green roofs support faunal diversity and what faunal taxa could exist on roofs; 5) if and how roof structural characteristics influence roof biodiversity; 6) what kinds of management are practiced on biodiversity roofs; 7) what are people s attitudes towards or perceptions of biodiversity roofs in general. In this study, I conduct that 1) Sunny dry habitats, such as meadows and tundra, can be regarded as 'model ecosystems' for biodiversity roofs in the Finnish context. 2) Substrate heterogeneity is a key to biodiversity on green roofs. Different materials and different combinations of materials could be applied on the same roof to mimic diverse types of soil types in the most biodiverse Finnish ecosystems. 3) Native species from the model ecosystems are ideal plants for biodiversity roofs. Combining multiple greening methods on the same roof can be a solution to achieve 'instant greening effects' with only native species. 4) An ideal biodiversity roof in the Finnish context could support birds, bats, and invertebrates, such as spiders. To attract and support fauna, a roof needs a diverse plant community, as well as extra elements, such as deadwood. 5) Roof structural characteristics (i.e. roof height, size, slope, direction, location, and age) impact biodiversity by determining the accessibility to and the dispersal of flora and fauna, as well as microclimates on roofs. 6) Management, such as irrigation, might help biodiversity at least for newly established biodiversity roofs, but biodiversity roofs aim at being self-sustaining eventually. 7) People have generally positive attitudes towards green roofs, but their willingness to actually install a biodiversity roof is influenced by other issues, such as the financial cost and roof safety.
  • Collins, Steven G. (Helsingfors universitet, 2016)
    Cities of the 21st century consume massive amounts of energy, and indoor climate control within the built environment is responsible for a large fraction of the total demand. With pressures to make buildings more environmentally friendly, new energy efficient technologies and designs are continually sought after. A green roof, or a living roof, is a structural design approach that can provide a variety of ecosystem services along with the reduction of building energy demands. It has been shown that green roofs are effective tools for reducing cooling energy demands in warm and sunny climates; however, in cold climates, where heat energy demands dominate, there is a lack of research and general uncertainty about how beneficial a green roof may be. This thesis, conducted during the winter of 2013-2014, focused on the thermal performance of green roofs in cold weather (winter) conditions. The aim of the study was to quantify the reduction in energy loss that a green roof achieves and to examine the thermal behaviour of each of the green roof layers. Extensive green roofs with hot boxes underneath were constructed in Lahti (southern Finland). Heat sensors were placed vertically through the bare and green roofs to measure linear heat transfer from the interior to the exterior. Heat transfer by conduction was assessed, and a steady state analysis was used to quantify heat flux values. Furthermore, a green roof thermal conductivity model was developed to estimate the thermal conductivity of each of the layers under various environmental conditions (changing moisture contents, frost depths, and during freezing and thawing periods). Monthly comparisons of the energy lost through the two roofing structures were quantified. My results showed that green roofs reduced the amount of energy loss through the surface compared to bare roofs throughout the winter season. The overall reduction in energy loss, due to the presence of green roofs, was on average, 32.6%. Layer analysis showed that thermal conductivity of each of the layers decreased when penetrated by frost. A frost depth that extended through the whole green roof yielded the highest thermal resistance for the green roof at 3.96 m2KW-1. Comparatively, the bare roof had a thermal resistance of 0.27 m2KW-1. During times of snow coverage, the snow acted as a good thermal insulator, reducing the relative benefits achieved from green roofs. During refreezing and thawing, the green roof experienced the lowest values of thermal resistance at 1.83 m2KW-1. These results can be used for quantifying possible heat loss reductions in similar climates using a similar green roof, and the layer analysis provides information of how to best design green roof components for thermal resistance.