Against the background of past, recent and future climate change, the present thesis addresses elevational shifts of alpine treelines in the Swedish Scandes. By definition, treeline refers to the elevation (m a.s.l.) at a specific site of the upper trees of a specific tree species, at least 2 m tall. Based on historical records, the first part of the thesis reports and analyzes the magnitude of treeline displacements for the main trees species (Betula pubescens ssp. czerepanovii, Picea abies and Pinus sylvestris) since the early 20th century. The study covered a large and heterogeneous region and more than 100 sites. Concurrent with temperature rise by c. 1.4 °C over the past century, maximum treeline advances of all species amount to about 200 m. That is virtually what should be predicted from the recorded temperature change over the same period of time. Thus, it appears that under ideal conditions, treelines respond in close equilibrium with air temperature evolution. However, over most parts of the landscape, conditions are not that ideal and treeline upshifts have therefore been much smaller. The main reason for that discrepancy was found to be topoclimatic constraints, i.e. the combined action of geomorphology, wind, snow distribution, soil depth, etc., which over large parts of the alpine landscape preclude treelines to reach their potential thermal limit. Recorded treeline advance by maximum 200 m or so over the past century emerges as a truly anomalous event in late Holocene vegetation history. The second part of the thesis is focused more on long-term changes of treelines and one specific and prevalent mechanism of treeline change. The first part of the thesis revealed that for Picea and Betula, treeline shift was accomplished largely by phenotypic transformation of old-established stunted and prostrate individuals (krummholz) growing high above the treeline. In obvious response to climate warming over the past century, such individuals have transformed into erect tree form, whereby the treeline (as defined here) has risen. As a means for deeper understanding of this mode of positional treeline change, extant clonal spruces, growing around the treeline, were radiocarbon dated from megafossil remains preserved in the soil underneath their canopies. It turned out that Picea abies in particular may attain almost eternal life due to its capability for vegetative reproduction and phenotypic plasticity. Some living clones were in fact inferred to have existed already 9500 years ago, and have thus persisted at the same spot throughout almost the entire Holocene. This contrasts with other tree species, which have left no living relicts from the early Holocene, when they actually grew equally high as the spruce. Thereafter they retracted by more than 300 m in elevation supporting that also on that temporal scale, treelines are highly responsive to climate change. The early appearance of Picea in the Scandes, suggests that Picea “hibernated” the last glacial phase much closer to Scandinavia than earlier thought. It has also immigrated to northern Sweden much earlier than the old-established wisdom. The experiences gained in this thesis should constitute essential components of any model striving to the project landscape ecological consequences of possible future climate shifts.

The genus Quercus L. is represented with more than 400 species in the world and 18 of these species are found naturally in Turkey. Although its taxonomical, phytogeographical and dendrological importance, the genus Quercus is still taxonomically one of the most problematical woody genus in Turkish flora. In this study, multivariate morphometric approach was used to analyze oak specimens collected from an isolated forest (Beynam Forest, Ankara) where Quercus pubescens Willd., Q. infectoria Olivier subsp. boissieri (Reuter) O. Schwarz and Q. macranthera Fisch. &amp / C. A. Mey. ex Hohen. subsp. syspirensis (C.Koch) Menitsky taxa are belonging to section Quercus sensu stricto (s.s.) are found. Additional oak specimens were included in the analysis for comparison. Morphometric study was based on 52 leaf characters such as, distance, angle, and area as well as counted, descriptive and calculated variables. Morphometric variables were calculated automatically by use of landmark and outline data. Random forest classification method was used to select discriminating variables and predict unidentified specimens by use of pre-identified training group. The results of the random forest variable selection procedure and the principal component analysis (PCA) showed that the morphometric variables could distinguish the specimens of Q. pubescens and Q. macranthera subsp. syspirensis mostly based on the overall leaf size and number of intercalary veins while the specimens of Q. infectoria subsp. boissieri were separated from others based on lobe and lamina base shape. Finally, micromorphological observations of abaxial lamina surface have been performed by scanning electron microscope (SEM) on selected specimens which were found useful to differentiate, particularly the specimens of Q. macranthera subsp. syspirensis and its putative hybrids from other taxa.

There is much evidence that herbivory is a key innovation for the tremendous success of insect. In this thesis I have investigated different aspects of host plant utilization and phenotypic plasticity using the polyphagous comma butterfly, Polygonia c-album. Even though external conditions affect a phenotypic plastic response, the outcome is often influenced by a genetic background which may differ among populations. In Paper I we suspected the genetic background to seasonal polymorphism to be X-linked. However, results from interspecific hybridization between two populations suggested that diapause response is instead inherited in a mainly autosomally additive fashion, with a possible influence of sexual antagonism on males. In Paper II we showed that female oviposition preference is not a plastic response influenced by larval experience, but has a genetic background coupled to host plant suitability. Further, there is a strong individual correlation between larval host plant acceptance and female host plant specificity (Paper III). We believe this to be a larval feed-back genetically linked to female host specificity: offspring to ‘choosy’ specialist mothers benefit by remaining on the original host while offspring to less discriminating generalist mothers should risk inspecting the surroundings, thus compensating for potential poor female choice. In the larval mid-gut, genes are differentially expressed depending on host plant diet (Paper IV). Therefore, we expected to find fitness consequences of host plant switch. However, although growth rate was affected in a few treatments, larvae were generally surprisingly good at adjusting to new diets (Paper V). To conclude, host plant choice in both female and larval life stage is connected to performance. Combined with increased understanding about the plastic response to diet intake and seasonal polymorphism we have gained further insights into the processes of local adaptations and speciation in the Lepidoptera. / At the time of the doctoral defense, the following papers were unpublished and had a status as follows: Paper 3: Submitted Manuscript; Paper 5: Manuscript

Abstract Disturbance may shift microbial communities from one state to another. However, species differ in their ecological characteristics and their abilities to withstand disturbance. No single species or individuals of a species exist alone, but they are parts of complex interaction networks including species above- and belowground. In boreal and subarctic forests, almost all plants and a high number of fungi form mycorrhizas at the plant roots. In mycorrhiza, the fungal partner harvests nutrients for the host plant and, in return, gains carbon from the plant. In general, these common associations benefit both partners, but as heterotrophs, fungi are dependent on carbon photosynthesized by plants, whereas plants can survive alone as autotrophs. In addition to mycorrhizal fungi, also other fungi, such as endophytes, saprotrophs and pathogens, live in and on plant roots. This thesis concerns the impacts of disturbance on fungi living in plant roots and in soil near the roots. I hypothesized that i) root-associated fungal (RAF) and soil fungal communities and colonization types change after disturbance, that ii) the observed shifts relate to disturbance intensity and that iii) they co-occur with changes in soil conditions and vegetation. Changes in RAF were studied as changes in root fungal colonization, or in fungal community composition. The latter were detected with next-generation sequencing methods. The responses of RAF to disturbance seemed to be context dependent and related to sources of fungal communities (e.g. soil, RAF networks), environmental conditions (e.g. soil pH and nutrients) and host performance. It seems that abundances of those RAF species, which are present in the roots first (priority effect), may be increased by disturbance. Research produced new information related to ecological roles of the genera Phialocephala and Meliniomyces. Altogether, the results indicate connections between both abiotic and biotic environments and RAF, and host species viability and RAF. / Tiivistelmä Häiriöt voivat siirtää eliöyhteisön tilasta toiseen. Lajien ominaisuudet ja häiriönsietokyvyt eroavat toisistaan. Mikään laji tai yksilö ei elä yksin, vaan lajit ovat osa maan ylä- ja alapuolelle ulottuvia monimutkaisia vuorovaikutusverkostoja. Boreaalisissa ja subarktisissa metsissä lähes kaikki kasvit ja useat sienet muodostavat sienijuuren eli mykorritsan. Mykorritsassa sieniosakas hankkii isäntäkasville ravinteita ja saa vastavuoroisesti kasvilta hiiltä. Tavallisesti nämä vuorovaikutussuhteet hyödyttävät molempia sienijuuren osakkaita, mutta toisenvaraisina (heterotrofeina) sienet ovat riippuvaisia kasvien yhteyttämästä hiilestä, kun taas tuottajina (autotrofeina) kasvit voivat elää itsenäisesti. Mykorritsasienten lisäksi kasvien juurissa elää yleisesti myös muita sieniä kuten endofyyttejä, saprotrofeja ja patogeeneja. Tämä väitöskirja käsittelee häiriön vaikutuksia sieniin, jotka elävät kasvien juurissa ja juuria ympäröivässä maassa. Hypoteesieni mukaan i) juurissa ja maassa elävien sienten yhteisöt ja kolonisaatiotyypit muuttuvat häiriön jälkeen, ii) muutokset liittyvät häiriön voimakkuuteen ja iii) muutokset tapahtuvat samanaikaisesti maan olosuhteiden ja kasvillisuuden muutoksien kanssa. Juurissa elävien sienten esiintymisen muutokset tutkittiin sienten kolonisaation tai yhteisörakenteen muutoksina. Sieniyhteisöt selvitettiin NGS-menetelmien avulla. Juurissa elävien sienten vasteet häiriöön vaikuttavat olevan tilannesidonnaisia ja liittyvän sienilajien lähteisiin (esim. maa, juurisieniverkostot), ympäristömuuttujiin (esim. maan pH, ravinteet) ja isäntäkasvin menestymiseen. Häiriö voi vahvistaa juurissa ensimmäisenä läsnä olevien sienilajien menestymistä (prioriteettivaikutus). Uutta tietoa tuotettiin Phialocephala ja Meliniomyces –sienisukujen ekologiasta, jota tunnetaan huonosti. Kaiken kaikkiaan, tulokset osoittavat yhteydet sekä elottoman ja elollisen ympäristön ja juurten sieniyhteisön että isäntäkasvin elinkyvyn ja juurten sieniyhteisön välillä.

Abstract The main objective of this thesis was to investigate tree - cover crop interactions and soil response in an intercropping system, in which leguminous and grass cover crops were used with birch (red-leaved Downy birch Betula pubescens L.). The investigation was conducted in two field experiments in a nursery and in a greenhouse experiment. In the latter the effect of the water supply in interspesific competition was also investigated. The cover crops in the field experiments were perennial clovers Trifolium pratense L., T. repens L. and T. hybridum L. and annual clovers T. incarnatum L., T. resupinatum L. and T. subterraneum L. and perennial Festuca rubra L. The height, stem diameter, leaf area and nutrient status of the birch were determined, as well as soil nutrient status and microbial characteristics. The cover crops in the greenhouse experiment were T. repens, T. subterraeum and F. rubra. The biomass, height, leaf area, leaf area index, specific leaf area and N concentration of the birch, the biomass and N concentration of the cover crops were measured, and soil N and microbial characteristics, as well. Bare ground was the control in all the experiments. The perennial clovers and Festuca strongly decreased the birch growth and nutrient status, but the annual clovers sown in midsummer in the field experiments provided about as good growth as bare ground. In the greenhouse experiment all cover crops were effective competitors with the birch. The soil NO3-N was, in general, the highest on bare ground and second highest in the annual clover plots. Though there were, in general, only minor differences in the soil nutrient concentrations between the treatments, there were significant differences in the tree growth and nutrient concentrations. The interspecific competition in this kind of intercropping system is mainly belowground. The growth reduction in the birch was mainly due to competition for nitrogen but water seems to play an important role in regulating the competitive interaction between the birch and cover crops. The competition for these resources seems to be most crucial at the beginning of the growing season. The microbial biomasses and soil respiration were greatest in the Festuca and perennial clover treatments, which may indicate that microorganisms together with these cover crops may seriously compete with birch for nutrients. Intercropping system is complex and comprises both negative and positive influences. In order to minimize negative competition effects, the cover crop should be non-competitive or the ground should be kept free of vegetation at the beginning of the growing season. By improving soil microbial characteristics, the vegetative ground covers make this cropping system one possiblity towards sustainability in the long-term.

Abstract Mycorrhizal fungi are important contributors to the functioning of boreal forests, since they act in the bilateral carbon and nutrient transport between above- and belowground parts of the ecosystem. In ectomycorrhizal (ECM) symbiosis of woody host plants, both fungal and plant partners depend on resources provided by the other. A single tree may simultaneously host several ECM fungal partners, which greatly enhance the host's nutrient uptake. At the same time nearly 20% of host primary production is allocated to mycorrhizal fungi. Although fungi depend on host-derived carbon, it is poorly understood how reduced carbon availability, e.g., due to herbivory, affects the ECM fungal symbionts. In this thesis I studied the impact of simulated insect defoliation or mammal browsing on mycorrhizal fungi of boreal woody hosts. Quantitative and qualitative changes in biomass partitioning in different fungal compartments were detected. None of the experiments showed that defoliation or shoot clipping treatments reduced the intensity of ECM colonisation, while treatments often shifted fungal composition towards less biomass producing ECM morphotypes. Above- and belowground diversity in ECM symbionts tended to decrease due to shoot or foliar damage. In addition, in some cases defoliation also reduced fungal biomass in fine roots and decreased ECM sexual reproduction by reducing the number of sporocarps produced. Defoliation induced a similar response pattern in the host and in ECM fungi with a stronger response to increasing severity of treatment (e.g. degree of removed foliage or repeated years of defoliation). This was also confirmed when relating the effects of host and ECM fungal symbionts to defoliation using present and previously published data. The present results suggest that belowground adaptation of boreal trees to the changing environment is mediated by changes in fungal community or biomass partitioning. The lack of response in the intensity of ECM colonisation further emphasises the importance of the symbiosis to boreal trees.

Made available in DSpace on 2014-07-29T15:30:42Z (GMT). No. of bitstreams: 1 Dissertacao WalmirtonBezerra.pdf: 3515322 bytes, checksum: 262c3d8c28e9609dbeee4234b3332f81 (MD5) Previous issue date: 2008-10-22 / Amblyomma cajennense (Fabricius, 1787) (Acari, Ixodidae) known as tick-star , is a ixodid heteroxenous tree-host found too often in horses. Have little specific parasite, particularly in periods of larvae and nymph, is considered the most important in ixodid transmission of spotted fever to humans in Brazil. Rhipicephalus sanguineus, tick ectoparasite mainly from domestic dogs in urban areas, but also parasite other mammals, birds and reptiles, is responsible for the transmission of pathogens to their hosts. By developing in synanthropic environments, with their immature stages occasionally infecting man, this ixodídeo could cause increased incidence of erliquiosis, babesiosis and spotted fever in humans. The difficulties in controlling these ixodids, including the development of resistance to some acaricides chemicals synthetic main products used in their control, studies to encourage development of alternative measures, more efficient and less environmental impact. The objective of this work was monitoring the susceptibility and/or resistance of R. sanguineus to 14 insecticide products/acaricides, among the most acaricide sold in Goiás for control of ectoparasites of medical and veterinary importance, and verify the potential of substances extracted from plants, Carapa guianensis AUBLET (Meliaceae), Piper hispidinervum C.DC. (Piperaceae) and Magonia pubescens St. Hil. (Sapindaceae) in botanical exploration of acaricides for control of A. cajennense and R. saguineus. Engorged female of R. sanguineus were collected in environments naturally infested frequented by dogs in different districts and municipalities of Goiânia. Engorged female of A. cajennense were collected on horses from rural farms of different neighborhoods and surrounding municipalities of Goiânia. In the laboratory they were washed with distilled water, dried with paper towel and put in incubators B.O.D., to conduct the oviposition. Envelopes were used to filter paper impregnated with different concentrations of synthetic chemical acaricides, of essential oils from the leaves and branches side of P. hispidinervum, essential oil coming seeds of C. guianensis and stem bark of M. pubescens. In the control group used up only distilled water and solvent. Bioassays were made in quadruplicate. In the first study, Lethal Concentrations, CL50 and CL99, after 24 h and 48 h of exposure were calculated for the products that caused a framework for possible resistance or resistance to larvicidal R. sanguineus, according to WHO criteria. There was a framework of resistance to the basic products of Cypermethrin, Cypermethrin + Piperonyl Butoxide (PBO), Deltamethrin, Permethrin and Amitraz in 24 h presenting mortalities of 58.36%, 71.36%, 48.7%, 64.5% and 77.8%, respectively. In 48 h of exposure to Amitraz the mortality rate was 88%, presenting a framework for possible resistance accounting for 0.07% of the products tested. The lethal concentrations CL50 and CL99 were: Cypermethrin (0.06% and 7.04%), Cypermethrin + PBO (0.06% and 2.1%), Deltamethrin (0.06% and 1.57%); Permethrin (0.06% and 0.3%), Amitraz 24 h (0025% and 0.73%) and Amitraz 48 h (0.06% and 0.31%). The products Deltamethrin, Cypermethrin, Permethrin, Cypermethrin + PBO and Amitraz (24 and 48 h of exposure) were 35.2, 21, 7.85, 3, 3.65, 1.55 times, respectively, higher than the dosages recommended by manufacturers. In the second study noted that the essential oil of C. guianensis on the larvae of A. cajennense resulted in 24 h, mortality not exceeding 10% for 35% concentration in 48 h of exposure received at the CL50 of 7.38% and 45.45% of CL99, the essential oil of P. hispidinervum shown in 24 h of exposure CL50 of 0.42% and CL99 of 0.88%, in 48 h of exposure CL50 of 0.45% and CL99 of 1.06%. There was Knock down the effect on the larvae of A. cajennense the essential oil of P. hispidinervum, significantly influencing mortality average. In the third study there was the lethal action of ethanol crude extract of stem of bark M. pubescens on R. sanguineus, in the reading of 48 h LC50 and CL99 was 0.15% and 0.99%, respectively.The plants showed larvicidal effect on A. cajennense and R. sanguineus. The essential oils and extracts studied demonstrated greatest potential for the exploration of acaricides plants, with less environmental impact, to be used as a strategy for control of R. sanguineus and A. cajennense. / Amblyomma cajennense (Fabricius, 1787) (Acari, Ixodidae) conhecido como carrapato-estrela , é um ixodídeo heteroxeno encontrado com muita freqüência em eqüídeos. Têm pouca especificidade parasitária, principalmente nos estágios de larva e ninfa, sendo considerado o ixodídeo mais importante na transmissão da febre maculosa para os humanos no Brasil. Rhipicephalus sanguineus, carrapato ectoparasita principalmente dos cães domésticos em áreas urbanizadas, mas que também parasita outros mamíferos, aves e répteis, é responsável pela transmissão de patógenos aos seus hospedeiros. Por se desenvolver em ambientes sinantrópicos, com seus estágios imaturos, parasitando ocasionalmente o homem, este ixodídeo poderá vir a causar aumento na incidência de erliquiose, babesiose e febre maculosa no homem. As dificuldades existentes no controle dos ixodídeos, incluindo o desenvolvimento de resistência a alguns acaricidas químicos sintéticos, principais produtos utilizados em seu controle, incitam estudos para desenvolvimento de medidas alternativas, mais eficientes e de menor impacto ambiental. O objetivo do presente trabalho foi monitorar a susceptibilidade e/ou resistência de R. sanguineus a 14 produtos inseticidas/acaricidas, dentre os mais comercializados em Goiás para controle de ectoparasitos de importância médica e veterinária, e verificar a potencialidade de substâncias extraídas das plantas Carapa guianensis AUBLET (Meliaceae), Piper hispidinervum C.DC. (Piperaceae) e Magonia pubescens St. Hil. (Sapindaceae), na prospecção de acaricidas botânicos para controle de A. cajennense e R. sanguineus. As teleóginas de R. sanguineus foram coletadas, em ambientes naturalmente infestados, freqüentados por cães, de diferentes bairros e municípios de Goiânia. Teleóginas de A. cajennense foram coletadas em cavalos oriundos de propriedades rurais de diferentes bairros e municípios circunvizinhos de Goiânia. No laboratório, as teleóginas foram lavadas com água destilada, secas em papel toalha e acondicionadas em incubadoras B.O.D., para realizarem a oviposição. Foram utilizados envelopes de papel filtro impregnados com diferentes concentrações dos acaricidas químicos sintéticos, óleo essencial provenientes das folhas e ramos secundários de P. hispidinervum, óleo essencial provindo das sementes de C. guianensis e o extrato bruto etanólico da casca do caule de M. pubescens. No grupo controle utilizou-se apenas água destilada e solvente. Os bioensaios foram realizados em quadruplicata. No primeiro estudo, Concentrações Letais, CL50 e CL99, após 24 h e 48 h de exposição foram calculadas para os produtos que proporcionaram um quadro de resistência ou possível resistência larvicida para R. sanguineus, segundo critérios da OMS. Observou-se resistência para as larvas de R. sanguineus produtos que apresentaram mortalidades a base de Cipermetrina (58,36%), Cipermetrina + Butóxido de Piperolina (PBO) (71,36%), Deltametrina (48,7%), Permetrina (64,5%) e Amitraz (77,8%) nas 24 h, correspondendo a 36% dos produtos testados. Em 48 h de exposição ao Amitraz a mortalidade foi de 88%, apresentando um quadro de possível resistência, correspondendo a 0,07% dos produtos testados. As concentrações letais CL50 e CL99 encontradas foram: Cipermetrina (0,06% e 7,04%), Cipermetrina + PBO (0,06% e 2,1%), Deltametrina (0,06% e 1,57%), Permetrina (0,06% e 0,3%), Amitraz 24 h (0,025% e 0,73%) e Amitraz 48 h (0,06% e 0,31%). Os produtos Deltametrina, Cipermetrina, Permetrina, Cipermetrina + PBO e Amitraz (24 e 48 h de exposição), foram 35,2; 21; 7,85; 3; 3,65; 1,55 vezes, respectivamente, maiores do que as dosagens recomendadas pelos fabricantes. No segundo estudo observou-se o efeito letal do óleo essencial de C. guianensis sobre as larvas de A. cajennense ocasionando nas 24 h, mortalidade não superior a 10% para concentração 35%, nas 48 h de exposição obtiveram-se as CL50 de 7,38% e CL99 de 45,45%. O óleo essencial de P. hispidinervum ocasionou nas 24 h de exposição CL50 de 0,42% e CL99 de 0,88%, nas 48 h de exposição CL50 de 0,45% e CL99 de 1,06%. Observou-se o efeito Knock down sobre as larvas de A. cajennense pelo óleo essencial de P. hispidinervum, influenciando significativamente na mortalidade média. No terceiro estudo observou-se a ação letal do extrato bruto etanólico da casca do caule de M. pubescens sobre R. sanguineus, em 48 h a CL50 e CL99 foi de 0,15% e 0,99%, respectivamente. Os óleos essenciais e extrato estudados demonstraram como método alternativo para a prospecção de acaricidas vegetais, de menor impacto ambiental, a serem utilizados como nova estratégia para controle de R. sanguineus e A. cajennense.

Thesis (doctoral)--Universiteit van Amsterdam, 1985. / Five charts in back cover pocket. Text in English, with foreword and summary in Dutch. Includes bibliographical references (p. 147-152).

Abstract Mechanical harvesting of peat changes the original mire ecosystem completely, and without active measures these areas may remain non-vegetated even for decades. Afforestation is one of the most popular after-use options for cut-away peatlands in Finland since it has both economic and aesthetic values. Recycling of wood-ash as a fertilizer has been studied extensively in peatlands drained for forestry. Wood-ash is reported to promote tree growth in these areas without any significant negative impact to the environment and could, therefore, be a suitable option also on cut-away peatlands. However, the environmental effects of ash-fertilization on cut-away areas and on ground vegetation are not fully understood. The impact of wood- and peat-ash application on the early establishment of ground vegetation and downy birch (Betula pubescens) seedlings and on post-fertilization element concentrations in plants and peat substrate were studied in a cut-away peatland. Six treatments of wood-ash, peat-ash, biotite or Forest PK-fertilizer were replicated in three blocks in different mixtures and quantities corresponding to 50 kg ha-1 of phosphorus. All the fertilizers accelerated the revegetation of the bare peat surface significantly, whereas the establishment of plants in the unfertilized area was non-existent even several years after the peat harvesting had ceased. The most striking difference between the wood- and peat-ash-fertilizers and the commercial Forest PK-fertilizer was the extensive coverage of fire-loving moss species in all the areas where ash was spread. Wood- and peat-ash application also accelerated the germination and early establishment of downy birch seedlings more efficiently than the PK-fertilizer. Ground vegetation proved to be highly important in increasing the early biomass production and carbon sequestration on ash-fertilized cut-away peatland. In addition, the below-ground biomass was equal to the above-ground biomass, or even greater. Both wood- and peat-ash fertilization ensured an adequate level of nutrients for the early establishment of ground vegetation and birch seedlings in a cut-away peatland. The mosses and herbaceous plants proved to have a major role in retaining the nutrients and heavy metals that otherwise might have leached away from the ash-fertilized cut-away site during the early stages of the afforestation. Although both wood- and peat-ash proved to be suitable for the initial fertilization of afforested cut-away peatlands, a later application of nutrients may be needed to guarantee the growth in a energy-wood stand of downy birch over its entire rotation. / Tiivistelmä Turvetuotannon päätyttyä jäljelle jäävä suopohja on aluksi täysin paljas ja vailla maaperän siemenpankkia. Kasvipeitteen luontainen uudistuminen voi viedä jopa vuosikymmeniä. Ympäristönhoidollisesti onkin tärkeää, että suopohjat otetaan uuteen käyttöön mahdollisimman nopeasti tuotannon päätyttyä. Metsitys on tällä hetkellä suosituin suopohjien jälkikäyttömuoto Suomessa. Suopohjan turpeessa on tyypillisesti runsaasti typpeä, mutta niukasti muita kasvuun tarvittavia ravinteita. Puutuhka on osoittautunut pitkäaikaisissa metsäojitettujen turvemaiden tutkimuksissa kilpailukykyiseksi vaihtoehdoksi kaupallisille lannoitteille. Energiantuotannon sivutuotteena syntyvä puu- ja turvetuhka voisi soveltua hyvin myös suopohjien lannoitteeksi. Tuhkan käytöstä lannoitteena turvetuotannosta vapautuneilla suopohjilla ei kuitenkaan ole riittävästi tutkimustietoa. Tässä työssä tutkittiin puu- ja turvetuhkan vaikutuksia turvetuotannosta vapautuneen suopohjan kasvittumiseen ja puun taimien alkukehitykseen viiden ensimmäisen kasvukauden ajan. Lisäksi tutkittiin kasvillisuuden ravinne- ja raskasmetallipitoisuuksien muutoksia sekä turpeen ravinteisuutta lannoituksen jälkeen. Kaikki lannoitteet nopeuttivat merkittävästi kasvillisuuden muodostumista paljaalle suopohjalle, kun taas lannoittamaton alue pysyi kasvittomana. Tuhkalannoitetuille alueille syntyi nopeasti laajoja palopaikoilla viihtyvien pioneerisammalten kasvustoja, jotka peittivät ja samalla sitoivat paljaan ja irtonaisen turvemaan pinnan. Tuhkalannoitus edisti myös koivun taimien alkukehitystä tehokkaammin kuin kaupallinen Metsän PK-lannoite. Sammalista ja ruohovartisista kasveista muodostuva aluskasvillisuus ylitti puuntaimet selvästi biomassan määrässä ja toimi metsityksen alkuvaiheessa puuntaimia merkittävämpänä hiilensitojana. Lisäksi kasvien maanalainen biomassa oli maanpäällistä biomassaa suurempi. Sekä puu- että turvetuhka takasivat riittävän määrän ravinteita energiapuumetsikön alkukehitykselle. Aluskasvillisuus osoittautui tärkeäksi tuhkasta liukenevien ravinteiden ja raskasmetallien sitojaksi metsityksen alkuvaiheessa. Vaikka sammalten kadmiumpitoisuudet nousivat tuhkalannoituksen seurauksena, ne olivat kuitenkin alhaisia Suomessa aiemmin mitattuihin sammalten yleisiin pitoisuuksiin suhteutettuna. Tuhkalannoitus ei lisännyt haitallisten raskasmetallien pitoisuuksia koivun taimien ja ruohovartisten kasvien lehdissä ja varsissa. Tutkimuksen tulokset tukevat puu- ja turvetuhkan käyttöä energiapuumetsiköiden alkuvaiheen lannoitteena turvetuotannosta vapautuneilla suopohjilla.

No description available.