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Browsing by Subject "taajamametsä"

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  • Suominen, Tiia (2015)
    The changing environment causes new needs and objectives for which new plans and strategies have to be created. The importance of the residents increases during these planning processes, and therefore utilizing different participatory methods comes more and more important. There are two parts in this research; the first part examines how the resident survey, from participatory methods, can be used in the strategical planning of the city’s forests’ use and management, and in the second part, the resident survey has been implemented to find out the opinions, wishes, and proposals of the residents concerning the city’s forests’ use and management in Vantaa. The first part of the research examines how the resident survey can be used in the achieving the objectives, what is the content that the resident survey is able to bring into the planning process, and to find out how and in which phase, or in which way, the resident survey can be used in the planning process. In this part, the qualitative methods were used, and the results are mainly based on the existing literature together with the implemented survey in the certain aspects. From the results, it is possible to find out that the resident survey may achieve very well the objectives of the municipality and the objectives relating residents’ local knowledge and possibilities to influence by certain criteria. The objectives related to the residents’ spiritual or psychological characteristics, like building the trust, are more difficult to achieve. On the other hand, the implemented resident survey cannot be used to achieve all the objectives of the international or institutional parts, like the objectives related to the Forest Act. It is possible to use the resident survey in every phase of the planning process, but according to the results of this research, it will not be able to bring all the objectives in every phase. The second part of the research was to implement the resident survey to find out the residents’ opinions, wishes, and proposals concerning the forests of Vantaa city. It enabled to gather the knowledge and the information about the meaning and the use of the forests, the acceptable forest management methods, the participatory in the forest management and planning, and the local information about the forests. Vantaa city was divided into the seven areas. The sample size was 2 100 – so 300 residents of the age 15 to 75 from each area. In total 950 answers were received with the respond rate 45 %. The results were created by using the quantitative methods. They show that the meaning of the forests for recreation and outdoor activities is remarkable; the most important characteristics are naturalness and feeling of the forest, calmness and silence, and the opportunities to outdoor activities and sport; the residents mostly use forests nearby home; and the most acceptable forest management methods cause less changes in the environment, like thinning, uneven-aged forest management, and harvesting. The participatory is quite unknown for most of the respondents, and the most of the residents think that this resident survey will not influence to the final decisions. Further studies about how the criteria, used in this research, could work with different resident surveys is needed, and if they can be used in the other phases of the planning process that have been found out in this research.
  • Elomaa, Satu (2019)
    Nature is important to people. Urban green areas maintain a big role in provision of citizens’ recreation. Due to increasing urbanization, urban green areas are constantly diminishing. This has caused concern and distress among citizens. Various forest management measures can also cause many different reactions. Thus, nature – forests, meadows, grass fields – hold different meanings for every person. Purpose of this study was to examine how the forest management measures made in western half of Keskuspuisto (Central Park) has impacted on users’ opinions about the area. The study was conducted via web-based survey tool Maptionnaire as a half-structured web survey. 341 users took part in the survey. In total, users marked 512 favourite places, and 116 unpleasant places. Results were examined using cross tabulation, Kruskal-Wallis -test and chi-squared test with a 5 % risk. Mapped responses were examined in QGIS-software, with which the thematic maps of social values were created. Results were compared to a 2009 visitor survey. The first point of interest was how, where and how often survey respondents visited the park. In addition, users' favourite places and unpleasant places and the relating social values were examined, and whether the forest management measures have had an impact on the mapped responses. The results can be used in the forthcoming nature- and landscape management plan in the western half of Keskuspuisto. Based on the results, the western half of Keskuspuisto is very important for its users and its use is versatile. Usage of the area has increased in the last 10 years. A statistical link was not found between forest management measures and mapped responses or social values. Opinions about the forest management of the area varied greatly. It can be concluded that the forest management actions in western part of Keskuspuisto have been quite successful. Users were in general satisfied, but many voiced a concern regarding the future of the area. It is hoped that the area is kept out of future construction plans. Due to varying opinions and wishes, it is important to take the citizens' opinions into account in the city planning. The method of mapping social values and mapping favourite places and unpleasant places were useful ways to gain important information regarding the users and which areas are important to them.
  • Karttunen, Toni (2014)
    Urban forests of Helsinki city are managed in multiple ways and several forest values are taken into account in forest management. Strong forest management actions that change the forest landscape radically have been done quite seldom, which has increased the proportion of old forests. The risk of spruce bark beetle (Ips typographus) outbreaks is often evident especially in older Norway spruce (Picea abies) forests of low vitality. In the winter of 2011 to 2012 storms caused windfalls in some areas of the urban forests in Helsinki city, which increased the risk of spruce bark beetle outbreaks even more. The objective of this study was to assessment the risk of spruce bark beetle outbreaks in the urban forest of Helsinki city and present future forest management recommendations to control the spruce bark beetle damage. Monitoring with pheromone baited traps was used as the main investigation method. Results were compared with spruce bark beetle risk estimates found in literature. Other factors affecting the risk of spruce bark beetle, for example the amount of living Norway spruces infested with the spruce bark beetle, were observed as well. Monitoring with pheromone traps was carried out with 36 traps in three regions in Helsinki Central Park and in one region in Herttoniemi between 6th of May and 4th of July in 2013. Pheromone trap model, WitaTrap Multi Funnel, and pheromone bait Ipsowit® Standard were manufactured by Witasek company. Altogether 79 210 spruce bark beetles were trapped. According to the monitoring results the risk of spruce bark beetle can be high in one region in Central Park area. Living Norway spruces infested by the spruce bark beetle were found in two regions and also in one area outside the investigation area. Based on the results the areas with greatest risk to spruce bark beetle damage were the neighboring areas of previous damage as well as forests with suitable breeding material for the spruce bark beetle. The risk can also be high in Norway spruce forests of low vitality and in recently formed, sun-exposed forest edges dominated by Norway spruce. Forest management recommendations in short time interval to control the spruce bark beetle risk are as follows 1) forest monitoring and removal of spruce bark beetle infested live Norway spruces before Midsummer, 2) observation of storm damage and removal of large diameter Norway spruce windfalls as a rule, 3) monitoring the weather conditions and 4) following national announcements related to the spruce bark beetle risk status. Forest management recommendations for longer time interval are phased regeneration fellings of risk prone Norway spruce forests and changing the forest structures more resistant to spruce bark beetle damage in the future.
  • Keinänen, Sini (2018)
    Forests are important carbon pools for combating climate change. Forest disturbances, such as insect outbreaks, can temporarily change a forest and forest soil to a source of carbon. Tree mortality reduces forest carbon uptake and increases emissions from the decay of killed trees. Climate change is expected to impact the susceptibility of forests to disturbances. For example, the number of insects in forests is predicted to increase and therefore the impact of pests on forest ecosystems will also increase. This can weaken forests carbon sequestration. The purpose of this master's thesis was to study the effect of the European spruce bark beetle (Ips typographus L.) on the carbon in the surface layers (humus and the mineral layer of depth 0‒5 cm) of the soil. In this study, the aim was to study the effect of tree mortality and tree damage intensity caused by the spruce bark beetle on the forest topsoil carbon stock. In addition, changes in the carbon content and C / N ratio of soil surface layers were studied. The aim was also to study the effect of stand- and tree-wise characteristics on the carbon content of the topsoil. The field work was carried out in urban forest area, in Lahti,Southern Finland. In years 2012–2013 stand- and tree-wise characteristics were measured on 49 plots. The spruce bark beetle-induced symptoms and forest site classification were also estimated. Further, three soil samples were taken from each plot for carbon analysis from the humus layer and 0‒5 cm depth of mineral soil. Proportion of carbon (C %) and C/N ratio were analysed from the samples and the amount of carbon (kg C m-2) was determined. The amount of carbon in the experimental area was on average 0.6 kg C m-2 and varied between plots 0.1 and 1.5 kg C m-2. The amount of carbon varied statistically significantly between forest types. At a more herb-rich forest types (OMT/OMaT-groups= more rich forest types), the soil carbon content was significantly higher than in MT-type. Also, the C / N ratio and C % were both significantly higher in the humus layer than in the mineral soil. In this study, the dead spruce trees (%), dead spruces diameter (d1,3) or basal area of dead spruce trees did not increase the amount of carbon in the surface layers of the soil. Also, the tree damage intensity caused by the spruce bark beetle did not explain the amount of carbon (kg C m-2), proportion (C%) or the C / N ratio of the soil surface layers. However, there was a correlation between the stand- and tree-wise characteristics and the carbon content of the soil in more rich vegetation/forest site (OMT/OMaT): The proportion of spruces showed a relationship with C % and C/N-ratio, and basal area of spruces with carbon content of the soil (kg C m-2). This study did not find a relationship between spruce bark beetle and surface layers of soil carbon. This may be due to the fact, that the time frame of this study was too short to observe any changes. In addition, this study did not compare fully healthy vs. seriously damaged spruce forests, in which case the difference in soil carbon content would have been observed. Furthermore, this study did not quantify potential changes in litter layer carbon caused by the spruce bark beetle. The following studies may need to be done over a longer period of time, adding control plots to the study, and also the carbon contained in the litter layer. On the other hand, many environmental factors affect to natural processes simultaneously. Therefore, studying a single variable may not necessarily give a true picture of causality in nature.
  • Vuorilampi, Heli (2023)
    Tutkimuksen tarkoitus oli selvittää miten metsänhoito tai hoitamattomuus vaikuttavat puiden uudistumiseen, ja mitkä ovat eri puulajien uudistumismahdollisuudet kaupunkimetsissä. Kaupunkimetsät sijaitsevat kaupunkialueella ja ovat pääasiallisesti virkistyskäytössä. Kaupunkimetsät ovat useimmiten jäänteitä isommista metsäalueista, ja niille on tyypillistä luontainen tai luontaisen kaltainen metsäkasvillisuus. Kaupunkimetsien puusto on usein kookkaampaa, läpimitaltaan suurempaa ja iältään vanhempaa kuin talousmetsissä. Myös lahopuun määrä on kaupunkimetsissä talousmetsiä suurempi. Tutkin puiden uudistumista 29 kuusivaltaisessa metsässä Lahdessa ja Tampereella. Tutkimusmetsistä seitsemän oli hoitamattomia luonnontilaisia metsiä, loput olivat eriasteisesti hoidettuja kaupunkimetsiä. Tutkimuksessa tarkasteltiin metsänhoitoluokan (hoitamaton, lievästi hoidettu, hoidettu), kuluneisuuden (%), pohjapinta-alan (m2) ja puustoisen alueen osuuden (50 m säteellä) vaikutusta kuusen, pihlajan ja valopuiden (koivut, haapa ja tammi) taimien esiintymistodennäköisyyteen sekä taimien ja taimilajien lukumäärään. Aineisto analysoitiin yleistetyillä lineaarisilla sekamalleilla. Lukumäärämalleihin otettiin mukaan havaintoyksiköt, missä kyseessä olevia taimia esiintyi. Tulosten perusteella havaittiin, että hoitamattomissa metsissä kuusen taimien esiintymistodennäköisyys oli merkittävästi suurempi kuin hoidetuissa metsissä. Lievästi hoidetuissa metsissä pihlajan ja valopuiden taimien esiintymistodennäköisyys oli suurempi verrattuna hoitamattomiin metsiin. Muiden selittävien tekijöiden vaikutus taimien esiintymistodennäköisyyteen oli vähäinen, lukuun ottamatta kuluneisuuden lisääntymistä, joka vähensi pihlajan taimien esiintymistodennäköisyyttä. Kuusen taimien määrä näytti kasvavan, kun puustoisen alueen osuus lisääntyi metsäkohteen ympärillä. Pihlajan taimia oli runsaammin hoidetuissa ja lievästi hoidetuissa metsissä kuin hoitamattomissa metsissä. Valopuiden taimien määrä puolestaan näytti olevan pienempi hoidetuissa metsissä, ja se väheni, kun puustoisen alueen osuus (50 m säteellä) ja kuluneisuus lisääntyivät. Metsänhoitoluokalla, puustoisen alueen osuudella metsäkohteen ympärillä (50 m säteellä), puuston pohjapinta-alalla (m2) tai maaperän kuluneisuudella (%) ei ollut merkitystä taimilajien lukumäärään. Tulosten perusteella erityisesti metsänhoito ja virkistyskäyttö vaikuttavat taimien esiintymiseen ja lukumäärään. Hoitotoimenpiteillä voidaan edistää haluttujen puulajien kasvua ja luoda suotuisampia olosuhteita uudistumiselle. Kaupunkimetsien hoidossa tulisikiinnittää erityisesti huomiota valopuiden uusiutumiseen, metsien monilajisuuteen ja latvuston kerroksellisuuteen.