Yhden uhka, toisen toive? : Somalien ja venäläisten asumistoiveet etnisen segregaatiokehityksen valossa

Ethnic minorities residential patterns and integration are widely discussed issues in many European countries. They have also become topical in Finland due to an increase in foreign migration, especially in recent decades. This dissertation contributes to debates associated with attempts to explain ethnic minorities residential patterns by examining the role of cultural factors and ethnic preferences of the residential choices of Somali and Russian immigrants in Finland. The research is based on in-depth interviews with Somali (n=24) and Russian (n=26) immigrants living in the Helsinki metropolitan area. Housing officials and social workers (n=18) working in cities of Helsinki and Vantaa were also interviewed. The results of this study show that propinquity to one s own ethnic group is important to Somalis living in Finland. This is important for maintaining their traditional, communal life styles, but also as a safe haven against the racism which they experience on a regular basis. They have a preference for mixed neighbourhoods that contain both native Finnish residents and some ethnic minorities. For Russians the spatial propinquity to their country people is less significant at the neighbourhood level. However, this is not to indicate the insignificance of intra-ethnic networks or one s cultural background. Rather, the differences in ethnic preferences between Somalis and Russians predominantly reflect their varying levels of exposure to racial harassment and diverse meanings that they give to social relations with their neighbours. According to this study, the time spent in a host-country and interactions with other ethnic groups affect ethnic preferences. The importance of one s own ethnic community also varies in accordance with life situations. Therefore, ethnic minorities residential preferences and choices should not be viewed as static or something deriving from cultural background alone. Residential preferences and aspirations are constantly being reshaped vis-à-vis to immigrants experiences. Past and present experiences and the way that immigrants observe the host society and its functions are important for the interpretation of residential preferences and patterns.

Pre-harvest measurement of pine stands for sawing production planning.

To enhance the utilization of the wood, the sawmills are forced to place more emphasis on planning to master the whole production chain from the forest to the end product. One significant obstacle to integrating the forest-sawmill-market production chain is the lack of appropriate information about forest stands. Since the wood procurement point of view in forest planning systems has been almost totally disregarded there has been a great need to develop an easy and efficient pre-harvest measurement method, allowing separate measurement of stands prior to harvesting. The main purpose of this study was to develop a measurement method for pine stands which forest managers could use in describing the properties of the standing trees for sawing production planning. Study materials were collected from ten Scots pine stands (Pinus sylvestris) located in North Häme and South Pohjanmaa, in southern Finland. The data comprise test sawing data on 314 pine stems, dbh and height measures of all trees and measures of the quality parameters of pine sawlog stems in all ten study stands as well as the locations of all trees in six stands. The study was divided into four sub-studies which deal with pine quality prediction, construction of diameter and dead branch height distributions, sampling designs and applying height and crown height models. The final proposal for the pre-harvest measurement method is a synthesis of the individual sub-studies. Quality analysis resulted in choosing dbh, distance from stump height to the first dead branch (dead branch height), crown height and tree height as the most appropriate quality characteristics of Scots pine. Dbh and dead branch height are measured from each pine sample tree while height and crown height are derived from dbh measures by aid of mixed height and crown height models. Pine and spruce diameter distribution as well as dead branch height distribution are most effectively predicted by the kernel function. Roughly 25 sample trees seems to be appropriate in pure pine stands. In mixed stands the number of sample trees needs to be increased in proportion to the intensity of pines in order to attain the same level of accuracy.

Production process of Scots pine.

The accompanying collective research report is the result of the research project in 1986­90 between The Finnish Academy and the former Soviet Academy of Sciences. The project was organized around common field work in Finland and in the former Soviet Union and theoretical analyses of tree growth determining processes. Based on theoretical analyses, dynamic stand growth models were made and their parameters were determined utilizing the field results. Annual cycle affects the tree growth. Our theoretical approach was based on adaptation to local climate conditions from Lapland to South Russia. The initiation of growth was described as a simple low and high temperature accumulation driven model. Linking the theoretical model with long term temperature data allowed us to analyze what type of temperature response produced favorable outcome in different climates. Initiation of growth consumes the carbohydrate reserves in plants. We measured the dynamics of insoluble and soluble sugars in the very northern and Karelian conditions. Clear cyclical pattern was observed but the differences between locations were surprisingly small. Analysis of field measurements of CO2 exchange showed that irradiance is the dominating factor causing variation in photosynthetic rate in natural conditions during summer. The effect of other factors is so small that they can be omitted without any considerable loss of accuracy. A special experiment carried out in Hyytiälä showed that the needle living space, defined as the ratio between the shoot cylindric volume and needle surface area, correlates with the shoot photosynthesis. The penetration of irradiance into Scots pine canopy is a complicated phenomenon because of the movement of the sun on the sky and the complicated structure of branches and needles. A moderately simple but balanced forest radiation regime submodel was constructed. It consists of the tree crown and forest structure, the gap probability calculation and the consideration of spatial and temporal variation of radiation inside the forest. The common field excursions in different geographical regions resulted in a lot of experimental data of regularities of woody structures. The water transport seems to be a good common factor to analyse these properties of tree structure. There are evident regressions between cross-sectional areas measured at different locations along the water pathway from fine roots to needles. The observed regressions have clear geographical trends. For example, the same cross-sectional area can support three times higher needle mass in South Russia than in Lapland. Geographical trends can also be seen in shoot and needle structure. Analysis of data published by several Russian authors show, that one ton of needles transpire 42 ton of water a year. This annual amount of transpiration seems to be independent of geographical location, year and site conditions. The produced theoretical and experimental material is utilised in the development of stand growth model that describes the growth and development of Scots pine stands in Finland and the former Soviet Union. The core of the model is carbon and nutrient balances. This means that carbon obtained in photosynthesis is consumed for growth and maintenance and nutrients are taken according to the metabolic needs. The annual photosynthetic production by trees in the stand is determined as a function of irradiance and shading during the active period. The utilisation of the annual photosynthetic production to the growth of different components of trees is based on structural regularities. Since the fundamental metabolic processes are the same in all locations the same growth model structure can be applied in the large range of Scots pine. The annual photosynthetic production and structural regularities determining the allocation of resources have geographical features. The common field measurements enable the application of the model to the analysis of growth and development of stands growing on the five locations of experiments. The model enables the analysis of geographical differences in the growth of Scots pine. For example, the annual photosynthetic production of a 100-year-old stand at Voronez is 3.5 times higher than in Lapland. The share consumed to needle growth (30 %) and to growth of branches (5 %) seems to be the same in all locations. In contrast, the share of fine roots is decreasing when moving from north to south. It is 20 % in Lapland, 15 % in Hyytiälä Central Finland and Kentjärvi Karelia and 15 % in Voronez South Russia. The stem masses (115­113 ton/ha) are rather similar in Hyytiälä, Kentjärvi and Voronez, but rather low (50 ton/ha) in Lapland. In Voronez the height of the trees reach 29 m being in Hyytiälä and Kentjärvi 22 m and in Lapland only 14 m. The present approach enables utilization of structural and functional knowledge, gained in places of intensive research, in the analysis of growth and development of any stand. This opens new possibilities for growth research and also for applications in forestry practice.

Onttojen puiden lahopuukovakuoriaiset — kolmen pyydystyypin vertailu

Vanhat ja ontot puut ovat tärkeä elinympäristö monelle lahopuusta riippuvaiselle eliölajille. Onttoihin puihin on erikoistunut suuri määrä myös vaarantuneita ja harvinaisia hyönteislajeja, jotka elävät puun onkalon seinämillä tai onkalon pohjalle kerääntyvässä orgaanisessa aineksessa, ns. mulmissa. Tutkimuksen tavoitteena oli selvittää, mikä kolmesta pyydystyypistä (ikkuna-, vuoka- ja kuoppapyydys) soveltuu parhaiten onttojen puiden lahopuukovakuoriaisten pyyntiin. Lisäksi tavoitteena oli kartoittaa hyönteisnäytteiden ensimmäiseen laboratoriokäsittelyyn vaadittua aikaa. Tutkimuksessa oli mukana vanhoja rungostaan onttoutuneita lehmuksia, tammia ja vaahteroita pääkaupunkiseudun puisto- ja kartanoalueilta. Puiden onkaloiden sisään aseteltiin ikkuna-, vuoka- ja kuoppapyydyksiä, kaksi kutakin tyyppiä ja ne tyhjennettiin kolmen viikon välein touko-heinäkuussa 2006. Pyydyksiä oli siis yhteensä 90 per pyyntijakso. Kun näytteistä eroteltiin halutut hyönteislahkot (mukaanlukien kovakuoriaiset) niiden käsittelyyn käytetty aika kirjattiin ylös. Aineistosta tunnistettiin yhteensä 3825 kovakuoriaisyksilöä ja 212 lajia, joista lahopuusta riippuvaisia oli yhteensä 3398 yksilöä ja 121 lajia. Ikkunapyydyksissä esiintyi yhteensä 1639 yksilöä ja 140 lajia, vuokapyydyksissä 1506 yksilöä ja 134 lajia, kuoppapyydyksissä 680 yksilöä ja 111 lajia. Näytteiden käsittelyaikojen keskiarvot olivat 48,3 minuuttia ikkunapyydykselle, 65,5 minuuttia vuokapyydykselle ja 34,1 kuoppapyydykselle. Lajistokoostumuksen huomioiva ?-diversiteetti erosi huomattavasti pyydysten välillä, se oli 36,5 % ikkuna- ja vuokapyydysten välillä, 13,1 % ikkuna- ja kuoppapyydysten välillä ja 14,2 % vuoka- ja kuoppapyydysten välillä. Ikkuna- ja vuokapyydysten välillä ei havaittu tilastollisesti merkitsevää eroa saproksyylilajien (p<0,05), -yksilöiden (p<0,05) tai käsittelyaikojen (p<0,05) keskiarvoissa. Ikkuna- ja vuokapyydyksillä saatiin keskimäärin selvästi enemmän saproksyylilajeja ja –yksilöitä kuoppapyydykseen verrattuna. Kuoppapyydyksellä saatiin kokonaisyksilömäärään verrattuna suhteellisesti vähemmän saproksyylejä (59 %) kuin ikkuna- (69 %) ja vuokapyydyksillä (71 %). Ikkunapyydykset olivat tehokkain pyydystyyppi vertailtaessa pyydysten keräämää saproksyyliyksilömäärää suhteessa aineiston käsittelyn vaatimaan aikaan. Tehokkuus (yksilöä minuutissa) ikkunapyydykselle oli 0,74, vuokapyydykselle 0,43 ja kuoppapyydykselle 0,21. Ikkunapyydyksiä ei ole aikaisemmin käytetty puun onkalon sisällä hyönteisiä pyydettäessä vaan ne ovat aikaisemmissa tutkimuksissa roikkuneet onkalon ulkopuolella. Ikkunapyydykset kuitenkin toimivat erinomaisesti myös onkaloiden sisällä. Ikkuna- sekä vuokapyydys toimivatkin selkeästi paremmin lahopuukovakuoriaisten pyynnissä verrattuna kuoppapyydykseen, jonka poisjättäminen olisi kuitenkin tuottanut huomattavasti lajiköyhemmän aineiston. Mahdollisimman monimuotoisen onttojen puiden lahopuukovakuoriaislajiston keräämiseksi tulisi käyttää ikkuna- tai vuokapyydyksiä yhdessä kuoppapyydysten kanssa.

What was behind the bark? : An assessment of decay among urban Tilia, Betula and Acer trees felled as hazardous in the Helsinki City area

Old trees growing in urban environments are often felled due to symptoms of mechanical defects that could be hazardous to people and property. The decisions concerning these removals are justified by risk assessments carried out by tree care professionals. The major motivation for this study was to determine the most common profiles of potential hazard characteristics for the three most common urban tree genera in Helsinki City: Tilia, Betula and Acer, and in this way improve management practices and protection of old amenity trees. For this research, material from approximately 250 urban trees was collected in cooperation with the City of Helsinki Public Works Department during 2001 - 2004. From the total number of trees sampled, approximately 70% were defined as hazardous. The tree species had characteristic features as potential hazard profiles. For Tilia trees, hollowed heartwood with low fungal activity and advanced decay caused by Ganoderma lipsiense were the two most common profiles. In Betula spp., the primary reason for tree removal was usually lowered amenity value in terms of decline of the crown. Internal cracks, most often due to weak fork formation, were common causes of potential failure in Acer spp. Decay caused by Rigidoporus populinus often increased the risk of stem breakage in these Acer trees. Of the decay fungi observed, G. lipsiense was most often the reason for the increased risk of stem collapse. Other fungi that also caused extensive decay were R. populinus, Inonotus obliquus, Kretzschmaria deusta and Phellinus igniarius. The most common decay fungi in terms of incidence were Pholiota spp., but decay caused by these species did not have a high potential for causing stem breakage, because it rarely extended to the cambium. The various evaluations used in the study suggested contradictions in felling decisions based on trees displaying different stages of decay. For protection of old urban trees, it is crucial to develop monitoring methods so that tree care professionals could better analyse the rate of decay progression towards the sapwood and separate those trees with decreasing amounts of sound wood from those with decay that is restricted to the heartwood area.

Archaea in the Mycorrhizosphere of Boreal Forest Trees

Archaea were long thought to be a group of ancient bacteria, which mainly lived in extreme environments. Due to the development of DNA sequencing methods and molecular phylogenetic analyses, it was shown that the living organisms are in fact divided into three domains; the Archaea, Bacteria and the Eucarya. Since the beginning of the previous decade, it was shown that archaea generally inhabit moderate environments and that these non-extremophilic archaea are more ubiquitous than the extremophiles. Group 1 of non-extreme archaea affiliate with the phylum Crenarchaeota. The most commonly found soil archaea belong to the subgroup 1.1b. However, the Crenarchaeota found in the Fennoscandian boreal forest soil belong to the subgroup 1.1c. The organic top layer of the boreal forest soil, the humus, is dominated by ectomycorrhizal fungal hyphae. These colonise virtually all tree fine root tips in the humus layer and have been shown to harbour distinct bacterial populations different from those in the humus. The archaea have also been shown to colonise both boreal forest humus and the rhizospheres of plants. In this work, studies on the archaeal communities in the ectomycorrhizospheres of boreal forest trees were conducted in microcosms. Archaea belonging to the group 1.1c Crenarchaeota and Euryarchaeota of the genera Halobacterium and Methanolobus were detected. The archaea generally colonised fungal habitats, such as ectomycorrhizas and external mycelia, rather than the non-mycorrhizal fine roots of trees. The species of ectomycorrhizal fungus had a great impact on the archaeal community composition. A stable euryarchaeotal community was detected especially in the mycorrhizas, of most of the tested Scots pine colonising ectomycorrhizal fungi. The Crenarchaeota appeared more sporadically in these habitats, but had a greater diversity than the Euryarchaeota. P. involutus mycorrhizas had a higher diversity of 1.1c Crenarchaeota than the other ectomycorrhizal fungi. The detection level of archaea in the roots of boreal trees was generally low although archaea have been shown to associate with roots of different plants. However, alder showed a high diversity of 1.1c Crenarchaeota, exceeding that of any of the tested mycorrhizas. The archaeal 16S rRNA genes detected from the non-mycorrhizal roots were different from those of the P. involutus mycorrhizas. In the phylogenetic analyses, the archaeal 16S rRNA gene sequences obtained from non-mycorrhizal fine roots fell in a separate cluster within the group 1.1c Crenarchaeota than those from the mycorrhizas. When the roots of the differrent tree species were colonised by P. involutus, the diversity and frequency of the archaeal populations of the different tree species were more similar to each other. Both Cren- and Euryarchaeota were enriched in cultures to which C-1 substrates were added. The 1.1c Crenarchaeota grew anaerobically in mineral medium with CH4 and CO2 as the only available C sources, and in yeast extract media with CO2 and CH4 or H2. The crenarchaeotal diversity was higher in aerobic cultures on mineral medium with CH4 or CH3OH than in the anaerobic cultures. Ecological functions of the mycorrhizal 1.1c Crenarchaeota in both anaerobic and aerobic cycling of C-1 compounds were indicated. The phylogenetic analyses did not divide the detected Crenarchaeota into anaerobic and aerobic groups. This may suggest that the mycorrhizospheric crenarchaeotal communities consist of closely related groups of anaerobic and aerobic 1.1c Crenarchaeota, or the 1.1c Crenarchaeota may be facultatively anaerobic. Halobacteria were enriched in non-saline anaerobic yeast extract medium cultures in which CH4 was either added or produced, but were not detected in the aerobic cultures. They may potentially be involved in anaerobic CH4 cycling in ectomycorrhizas. The CH4 production of the mycorrhizal samples was over 10 times higher than for humus devoid of mycorrhizal hyphae, indicating a high CH4 production potential of the mycorrhizal metanogenic community. Autofluorescent methanogenic archaea were detected by microscopy and 16S rRNA gene sequences of the genus Methanolobus were obtained. The archaeal community depended on both tree species and the type of ectomycorrhizal fungus colonising the roots and the Cren- and Euryarchaeota may have different ecological functions in the different parts of the boreal forest tree rhizosphere and mycorrhizosphere. By employing the results of this study, it may be possible to isolate both 1.1c Crenarchaeota as well as non-halophilic halobacteria and aerotolerant methanogens from mycorrhizospheres. These archaea may be used as indicators for change in the boreal forest soil ecosystem due to different factors, such as exploitations of forests and the rise in global temperature. More information about the microbial populations with apparently low cell numbers but significant ecological impacts, such as the boreal forest soil methanogens, may be of crucial importance to counteract human impacts on such globally important ecosystems as the boreal forests.