Ecological impacts of Phlebiopsis gigantea biocontrol treatment against Heterobasidion spp. as revealed by fungal community profiling and population analyses

Wood decay fungi belonging to the species complex Heterobasidion annosum sensu lato are among the most common and economically important species causing root rot and stem decay in conifers of the northern temperate regions. New infections by these pathogens can be suppressed by tree stump treatments using chemical or biological control agents. In Finland, the corticiaceous fungus Phlebiopsis gigantea has been formulated into a commercial biocontrol agent called Rotstop (Verdera Ltd.). This thesis addresses the ecological impacts of Rotstop biocontrol treatment on the mycoflora of conifer stumps. Locally, fungal communities within Rotstop-treated and untreated stumps were analyzed using a novel method based on DGGE profiling of small subunit ribosomal DNA fragments amplified directly from wood samples. Population analyses for P. gigantea and H. annosum s.l. were conducted to evaluate possible risks associated with local and/or global distribution of the Rotstop strain. Based on molecular community profiling by DGGE, we detected a few individual wood-inhabiting fungal species (OTUs) that seemed to have suffered or benefited from the Rotstop biocontrol treatment. The DGGE analyses also revealed fungal diversity not retrieved by cultivation and some fungal sequence types untypical for decomposing conifer wood. However, statistical analysis of DGGE community profiles obtained from Rotstop-treated and untreated conifer stumps revealed that the Rotstop treatment had not caused a statistically significant reduction in the species diversity of wood-inhabiting fungi within our experimental forest plots. Locally, ISSR genotyping of cultured P. gigantea strains showed that the Rotstop biocontrol strain was capable of surviving up to six years within treated Norway spruce stumps, while in Scots pine stumps it was sooner replaced by successor fungal species. In addition, the spread of resident P. gigantea strains into Rotstop-treated forest stands seemed effective in preventing the formation of genetically monomorphic populations in the short run. On a global scale, we detected a considerable level of genetic differentiation between the interfertile European and North American populations of P. gigantea. These results strongly suggest that local biocontrol strains should be used in order to prevent global spread of P. gigantea and hybrid formation between geographically isolated populations. The population analysis for H. annosum s.l. revealed a collection of Chinese fungal strains that showed a high degree of laboratory fertility with three different allopatric H. annosum s.l. taxa. However, based on the molecular markers, the Chinese strains could be clearly affiliated with the H. parviporum taxonomical cluster, which thus appears to have a continuous distribution range from Europe through southern Siberia to northern China. Keywords: Rotstop, wood decay, DGGE, ISSR fingerprinting, ribosomal DNA

Effects of recreational use and fragmentation on the understorey vegetation and soil microbial communities of urban forests in southern Finland

The impacts of fragmentation and recreational use on the hemiboreal urban forest understorey vegetation and the microbial community of the humus layer (the phospholipid fatty acid (PLFA) pattern, microbial biomass and microbial activity, measured as basal respiration) were examined in the greater Helsinki area, southern Finland. Trampling tolerance of 1) herb-rich OMT, 2) mesic MT, and 3) sub-xeric VT forests (in decreasing order of fertility) was studied by comparing relative understorey vegetation cover (urban/untrampled reference ratio) of the three forest types. The trampling tolerance of forest vegetation increased with the productivity of the site (sub-xeric < mesic < herb-rich). Wear of understorey vegetation correlated positively with the number of residents (i.e., recreational pressure) around the forest patch. An increase of 15000 residents within a radius of 1 km around a forest patch was associated with ca. 30% decrease in the relative understorey vegetation cover. The cover of dwarf shrub Vaccinium myrtillus in particular decreased with increasing levels of wear. The cover of mosses in urban forests was less than half of that in untrampled reference areas. Cover of tree saplings, mainly Sorbus aucuparia, and some resilient herbs was higher than in the reference areas. In small urban forest fragments, broad-leaved trees, grasses and herbs were more abundant and mosses were scarcer than in larger urban forest areas. Thus, due to trampling and edge effects, resilient herb and grass species are replacing sensitive dwarf shrubs, mosses and lichens in urban forests. Differences in the soil microbial community structure were found between paths and untrampled areas and the effects of paths extended more than one meter from the paths. Paths supported approximately 25-30% higher microbial biomass with a transition zone of at least 1 m from the path edge. However, microbial activity per unit of biomass was lower on paths than in untrampled areas. Furthermore, microbial biomass and activity were 30-45% lower at the first 20 m into the forest fragments, due to low moisture content of humus near the edge. The decreased microbial activity detected at forest edges and paths implies decreased litter decomposition rates, and thus, a change in nutrient cycling. Changes in the decomposition and nutrient supply may in turn affect the diversity and function of plant communities in urban forests. Keywords: boreal forest vegetation, edge effects, phospholipid fatty acids, trampling, urban woodlands, wear

The range expansion of the European map butterfly in Finland

Climate change will influence the living conditions of all life on Earth. For some species the change in the environmental conditions that has occurred so far has already increased the risk of extinction, and the extinction risk is predicted to increase for large numbers of species in the future. Some species may have time to adapt to the changing environmental conditions, but the rate and magnitude of the change are too great to allow many species to survive via evolutionary changes. Species responses to climate change have been documented for some decades. Some groups of species, like many insects, respond readily to changes in temperature conditions and have shifted their distributions northwards to new climatically suitable regions. Such range shifts have been well documented especially in temperate zones. In this context, butterflies have been studied more than any other group of species, partly for the reason that their past geographical ranges are well documented, which facilitates species-climate modelling and other analyses. The aim of the modelling studies is to examine to what extent shifts in species distributions can be explained by climatic and other factors. Models can also be used to predict the future distributions of species. In this thesis, I have studied the response to climate change of one species of butterfly within one geographically restricted area. The study species, the European map butterfly (Araschnia levana), has expanded rapidly northwards in Finland during the last two decades. I used statistical and dynamic modelling approaches in combination with field studies to analyse the effects of climate warming and landscape structure on the expansion. I studied possible role of molecular variation in phosphoglucose isomerase (PGI), a glycolytic enzyme affecting flight metabolism and thereby flight performance, in the observed expansion of the map butterfly at two separate expansion fronts in Finland. The expansion rate of the map butterfly was shown to be correlated with the frequency of warmer than average summers during the study period. The result is in line with the greater probability of occurrence of the second generation during warm summers and previous results on this species showing greater mobility of the second than first generation individuals. The results of a field study in this thesis indicated low mobility of the first generation butterflies. Climatic variables alone were not sufficient to explain the observed expansion in Finland. There are also problems in transferring the climate model to new regions from the ones from which data were available to construct the model. The climate model predicted a wider distribution in the south-western part of Finland than what has been observed. Dynamic modelling of the expansion in response to landscape structure suggested that habitat and landscape structure influence the rate of expansion. In southern Finland the landscape structure may have slowed down the expansion rate. The results on PGI suggested that allelic variation in this enzyme may influence flight performance and thereby the rate of expansion. Genetic differences of the populations at the two expansion fronts may explain at least partly the observed differences in the rate of expansion. Individuals with the genotype associated with high flight metabolic rate were most frequent in eastern Finland, where the rate of range expansion has been highest.

Microbial communities in Pb contaminated boreal forest soil

Lead contamination in the environment is of particular concern, as it is a known toxin. Until recently, however, much less attention has been given to the local contamination caused by activities at shooting ranges compared to large-scale industrial contamination. In Finland, more than 500 tons of Pb is produced each year for shotgun ammunition. The contaminant threatens various organisms, ground water and the health of human populations. However, the forest at shooting ranges usually shows no visible sign of stress compared to nearby clean environments. The aboveground biota normally reflects the belowground ecosystem. Thus, the soil microbial communities appear to bear strong resistance to contamination, despite the influence of lead. The studies forming this thesis investigated a shooting range site at Hälvälä in Southern Finland, which is heavily contaminated by lead pellets. Previously it was experimentally shown that the growth of grasses and degradation of litter are retarded. Measurements of acute toxicity of the contaminated soil or soil extracts gave conflicting results, as enchytraeid worms used as toxicity reporters were strongly affected, while reporter bacteria showed no or very minor decreases in viability. Measurements using sensitive inducible luminescent reporter bacteria suggested that the bioavailability of lead in the soil is indeed low, and this notion was supported by the very low water extractability of the lead. Nevertheless, the frequency of lead-resistant cultivable bacteria was elevated based on the isolation of cultivable strains. The bacterial and fungal diversity in heavily lead contaminated shooting sectors were compared with those of pristine sections of the shooting range area. The bacterial 16S rRNA gene and fungal ITS rRNA gene were amplified, cloned and sequenced using total DNA extracted from the soil humus layer as the template. Altogether, 917 sequenced bacterial clones and 649 sequenced fungal clones revealed a high soil microbial diversity. No effect of lead contamination was found on bacterial richness or diversity, while fungal richness and diversity significantly differed between lead contaminated and clean control areas. However, even in the case of fungi, genera that were deemed sensitive were not totally absent from the contaminated area: only their relative frequency was significantly reduced. Some operational taxonomic units (OTUs) assigned to Basidiomycota were clearly affected, and were much rarer in the lead contaminated areas. The studies of this thesis surveyed EcM sporocarps, analyzed morphotyped EcM root tips by direct sequencing, and 454-pyrosequenced fungal communities in in-growth bags. A total of 32 EcM fungi that formed conspicuous sporocarps, 27 EcM fungal OTUs from 294 root tips, and 116 EcM fungal OTUs from a total of 8 194 ITS2 454 sequences were recorded. The ordination analyses by non-parametric multidimensional scaling (NMS) indicated that Pb enrichment induced a shift in the EcM community composition. This was visible as indicative trends in the sporocarp and root tip datasets, but explicitly clear in the communities observed in the in-growth bags. The compositional shift in the EcM community was mainly attributable to an increase in the frequencies of OTUs assigned to the genus Thelephora, and to a decrease in the OTUs assigned to Pseudotomentella, Suillus and Tylospora in Pb-contaminated areas when compared to the control. The enrichment of Thelephora in contaminated areas was also observed when examining the total fungal communities in soil using DNA cloning and sequencing technology. While the compositional shifts are clear, their functional consequences for the dominant trees or soil ecosystem remain undetermined. The results indicate that at the Hälvälä shooting range, lead influences the fungal communities but not the bacterial communities. The forest ecosystem shows apparent functional redundancy, since no significant effects were seen on forest trees. Recently, by means of 454 pyrosequencing , the amount of sequences in a single analysis run can be up to one million. It has been applied in microbial ecology studies to characterize microbial communities. The handling of sequence data with traditional programs is becoming difficult and exceedingly time consuming, and novel tools are needed to handle the vast amounts of data being generated. The field of microbial ecology has recently benefited from the availability of a number of tools for describing and comparing microbial communities using robust statistical methods. However, although these programs provide methods for rapid calculation, it has become necessary to make them more amenable to larger datasets and numbers of samples from pyrosequencing. As part of this thesis, a new program was developed, MuSSA (Multi-Sample Sequence Analyser), to handle sequence data from novel high-throughput sequencing approaches in microbial community analyses. The greatest advantage of the program is that large volumes of sequence data can be manipulated, and general OTU series with a frequency value can be calculated among a large number of samples.

The effects of habitat edges and trampling intensity on vegetation in urban forests

Although changes in urban forest vegetation have been documented in previous Finnish studies, the reasons for these changes have not been studied explicitly. Especially, the consequences of forest fragmentation, i.e. the fact that forest edges receive more solar radiation, wind and air-borne nutrients than interiors have been ignored. In order to limit the change in urban forest vegetation we need to know why it occurs. Therefore, the effects of edges and recreational use of urban forests on vegetation were investigated together in this thesis to reveal the relative strengths of these effects and to provide recommendations for forest management. Data were collected in the greater Helsinki area (in the cities of Helsinki, Vantaa and Espoo, and in the municipalities of Sipoo and Tuusula) and in the Lahti region (in the city of Lahti and in the municipality of Hollola) by means of systematic and randomized vegetation and soil sampling and tree measurements. Sample plots were placed from the forest edges to the interiors to investigate the effects of forest edges, and on paths of different levels of wear and off these paths to investigate the effects of trampling. The natural vegetation of mesic and sub-xeric forest site types studied was sensitive both to the effects of the edge and to trampling. The abundances of dwarf shrubs and bryophytes decreased, while light- and nitrogen-demanding herbs and grasses - and especially Sorbus aucuparia – were favoured at the edges and next to the paths. Results indicated that typical forest site types at the edges are changing toward more nitrophilic vegetation communities. Covers of the most abundant forest species decreased considerably – even tens of percentages – from interiors to the edges indicating strong edge effects. These effects penetrated at least up to 50 m from the forest edges into the interiors, especially at south to west facing open edges. The effects of trampling were pronounced on paths and even low levels of trampling decreased the abundances of certain species considerably. The effects of trampling extended up to 8 m from path edges. Results showed that the fragmentation of urban forest remnants into small and narrow patches should be avoided in order to maintain natural forest understorey vegetation in the urban setting. Thus, urban forest fragments left within urban development should be at least 3 ha in size, and as circular as possible. Where the preservation of representative original forest interior vegetation is a management aim, closed edges with conifers can act as an effective barrier against solar radiation, wind and urban load, thereby restricting the effects of the edge. Tree volume at the edge should be at least 225-250 m3 ha-1 and the proportion of conifers (especially spruce) 80% or more of the tree species composition. Closed, spruce-dominated edges may also prevent the excessive growth of S. aucuparia saplings at urban forest edges. In addition, closed edges may guide people’s movements to the maintained paths, thus preventing the spontaneous creation of dense path networks. In urban areas the effects of edges and trampling on biodiversity may be considerable, and are important to consider when the aim of management is to prevent the development of homogeneous herb-grass dominated vegetation communities, as was observed at the investigated edges.

Sireenit, floksit ja iirikset- Puu-Käpylän koristekasvit

Puu-Käpylä (“Wooden Käpylä”), a neighbourhood of Helsinki, is the earliest example of the Garden City Movement in Finland. The suburb of valuable wooden architecture was built between 1920 and 1925, with the aim to provide a healthy housing area for working-class families with many children. The houses were erected by a co-operative (Käpylän kansanasunnot, “People?s Dwellings”) and they are protected by the city plan since 1960?s. However, the historical value of the sheltered courtyards has not been investigated. The aim of this study was to survey the garden flora of Puu-Käpylä and to evaluate the authenticity of the courtyard gardens. The survey covered the area of one residential quarter (1.2 ha) with twelve 2-storey semi-detached timber houses arranged around a common yard, which was originally appointed for the tenants? vegetable gardens. The houses are still rented, and each flat is allowed a small lot of the courtyard for cultivation. A complete list was made of all perennial, ornamental plant taxa present in the quarter. Spring bulbs were missed due to the timing of the survey. Generally, the plants were recorded on species level, with the exception of common lilacs, shrub roses, irises and peonies that were thoroughly studied for cultivar identification. It was assumed that plants initially grown in the courtyard could be distinguished by studying Finnish garden magazines, books and nursery catalogues published in the 1920?s and by comparing the present vegetation to surviving documents from the quarter. The total number of ornamental plant taxa identified was 172, of which 17 were trees, 47 shrubs, 7 climbers and 101 herbaceous perennials. The results indicated that a major part of the shrubs, climbers and perennials presumably originated from the 1970?s or later, whereas ca. 70 % of the tree specimens were deemed as original. The survey disclosed a heritage variety of common lilac, resembling cultivar „Prince Notger?, a specific peony taxon, Paeonia humilis Retz., cultivated in Nordic countries since long ago, and a few historic iris varieties. Well-preserved design elements included front gardens on one side of the quarter, a maple alley on another side as well as trees at the garden gates. Old garden books and magazines did not shed much light on the Finnish garden flora commonly used in the period when Puu-Käpylä was built. However, they gave a valuable picture of contemporary planting design. Nursery catalogues offered insight into the assortment of ornamental plants traded in the 1920?s. Conclusions on the authenticity of the current flora were mainly drawn on the basis of old photographs and a vegetation survey map drawn in the 1970?s. This study revealed a need for standardization of syrvey methods applied when investigating garden floras. Uniform survey techniques would make the results comparable and enable a future compilation of data from e.g. historic gardens.

Using a botanic garden collection to test a bioclimatic vegetation scheme

Vegetation maps and bioclimatic zone classifications communicate the vegetation of an area and are used to explain how the environment regulates the occurrence of plants on large scales. Many practises and methods for dividing the world’s vegetation into smaller entities have been presented. Climatic parameters, floristic characteristics, or edaphic features have been relied upon as decisive factors, and plant species have been used as indicators for vegetation types or zones. Systems depicting vegetation patterns that mainly reflect climatic variation are termed ‘bioclimatic’ vegetation maps. Based on these it has been judged logical to deduce that plants moved between corresponding bioclimatic areas should thrive in the target location, whereas plants moved from a different zone should languish. This principle is routinely applied in forestry and horticulture but actual tests of the validity of bioclimatic maps in this sense seem scanty. In this study I tested the Finnish bioclimatic vegetation zone system (BZS). Relying on the plant collection of Helsinki University Botanic Garden’s Kumpula collection, which according to the BZS is situated at the northern limit of the hemiboreal zone, I aimed to test how the plants’ survival depends on their provenance. My expectation was that plants from the hemiboreal or southern boreal zones should do best in Kumpula, whereas plants from more southern and more northern zones should show progressively lower survival probabilities. I estimated probability of survival using collection database information of plant accessions of known wild origin grown in Kumpula since the mid 1990s, and logistic regression models. The total number of accessions I included in the analyses was 494. Because of problems with some accessions I chose to separately analyse a subset of the complete data, which included 379 accessions. I also analysed different growth forms separately in order to identify differences in probability of survival due to different life strategies. In most analyses accessions of temperate and hemiarctic origin showed lower survival probability than those originating from any of the boreal subzones, which among them exhibited rather evenly high probabilities. Exceptionally mild and wet winters during the study period may have killed off hemiarctic plants. Some winters may have been too harsh for temperate accessions. Trees behaved differently: they showed an almost steadily increasing survival probability from temperate to northern boreal origins. Various factors that could not be controlled for may have affected the results, some of which were difficult to interpret. This was the case in particular with herbs, for which the reliability of the analysis suffered because of difficulties in managing their curatorial data. In all, the results gave some support to the BZS, and especially its hierarchical zonation. However, I question the validity of the formulation of the hypothesis I tested since it may not be entirely justified by the BZS, which was designed for intercontinental comparison of vegetation zones, but not specifically for transcontinental provenance trials. I conclude that botanic gardens should pay due attention to information management and curational practices to ensure the widest possible applicability of their plant collections.

Fishes of the Darkness : Water colour-regulated competitive interactions in humic lakes

Humic lakes are abundant in the temperate and cold regions of the Boreal Zone. High levels of water colour and strong thermal stratification of humic lakes limit the potential fish habitats and give a special role to the intraspecific and interspecific interactions. Water colour has different effects on species depending on species-specific life-history traits and trophic interactions. Fish species whose success in predation is based on visual cues are more susceptible to suffer in competition. The main aim of the thesis was to demonstrate the effects of water colour on European perch (Perca fluviatilis) in humic lakes. The contribution of water colour to diet, feeding, growth and competitive interactions of fish was studied both in laboratory and in small humic lakes with varying levels of water colour. The main findings of the thesis were that water colour has different effects on species, depending on species-specific life-history traits and trophic interactions. Water colour affected visually-oriented perch feeding and growth negatively, and the prolonged benthic feeding phase of perch resulting from the increased water colour could increase intraspecific competition in perch populations and may result in a partial bottleneck in growth for perch. Moreover, water colour may act as a proximate factor behind the population dependency of sexual growth dimorphism in perch.

Viherrevonhäntä ja kananhirssi vieraslajeina Suomessa

Kasvit ovat kautta aikojen levinneet uusille elinpaikoille. Kasvin asettumista uuteen paikkaan voidaan tarkastella prosessina, jossa on erilaisia vaiheita ja eri vaiheissa eri tekijät ovat tärkeitä. Ilmasto ja erityisesti lämpötila vaikuttavat kasvien levinneisyyteen ja leviämiseen uusille paikoille ja siksi ilmaston lämpenemisen ennustetaan siirtävän kasvien levinneisyysalueita kohti pohjoista. On mahdollista, että Suomeenkin leviäisi etelämmästä muiden kasvien ohella haitallisia rikkakasvilajeja, kuten esimerkiksi viherrevonhäntä (Amaranthus retroflexus L.) ja kananhirssi (Echinochloa crus-galli L. Beauv.). Tämän tutkimuksen tarkoituksena oli selvittää, selviävätkö viherrevonhäntä ja kananhirssi Suomessa pelto-olosuhteissa ja pohtia niiden vakiintumisen ja leviämisen mahdollisuuksia. Toinen tarkoitus oli selvittää ilmaston lämpenemisen vaikutusta näiden rikkakasvien kasvuun. Tutkimus suoritettiin kenttä- sekä kasvihuonekokeena. Viherrevonhäntä kasvoi pellolla hyvin huolimatta myöhäisestä itämisestä, mutta kananhirssi iti ja kasvoi pellolla huonosti. Kasvihuoneessa molemmat kasvoivat hyvin. Kilpailu vähensi viherrevonhännän ja kananhirssin vegetatiivista kasvua vain kasvihuoneessa, mutta siementuottoon kilpailu vaikutti sekä kasvihuoneessa että pellolla. Kasvihuoneessa korkeampi lämpötila ei vaikuttanut viherrevonhännän tai kananhirssin vegetatiiviseen kasvuun, mutta viherrevonhännän siementuotto parani lämpimämmässä. Lämpötilalla ei ollut vaikutusta kananhirssin siementuotantoon. Tutkimuksen tuloksista voidaan päätellä, että viherrevonhäntä voi hyvinkin kasvaa Suomessa jo nykyisissä lämpötiloissa, mutta siementuotto ei välttämättä olisi varmaa. Viherrevonhäntä voisi näin ollen hyötyä tulevaisuuden pidemmästä kasvukaudesta. Kananhirssin osalta tulokset olivat ristiriitaiset ja ilmaston lämpenemisen vaikutuksia kananhirssiin on tämän tutkimuksen perusteella hankala arvioida.

Photosynthesis of ground vegetation in boreal Scots pine forests

Research on carbon uptake in boreal forests has mainly focused on mature trees, even though ground vegetation species are effective assimilators and can substantially contribute to the CO2 uptake of forests. Here, I examine the photosynthesis of the most common species of ground vegetation in a series of differently aged Scots pine stands, and at two clear-cut sites with substantial differences in fertility. In general, the biomass of evergreen species was highest at poor sites and below canopies, whereas grasses and herbs predominated at fertile sites and open areas. Unlike mosses, the measured vascular species showed clear annual cycles in their photosynthetic activity, which increased earlier and decreased later in evergreen vascular species than in deciduous species. However, intraspecific variation and self-shading create differences in the overall level of photosynthesis. Light, temperature history, soil moisture and recent possible frosts could explain the changes in photosynthesis of low shrubs and partially also some changes in deciduous species. Light and the occurrence of rain events explained most of the variation in the photosynthesis of mosses. The photosynthetic production of ground vegetation was first upscaled, using species-specific and mass-based photosynthetic activities and average biomass of the site, and then integrated over the growing season, using changes in environmental factors. Leaf mass-based photosynthesis was highest in deciduous species, resulting in notably higher photosynthetic production at fertile sites than at poor clear-cut sites. The photosynthetic production decreased with stand age, because flora changed towards evergreen species, and light levels diminished below the canopy. In addition, the leaf mass-based photosynthetic activity of some low shrubs declined with the age of the surrounding trees. Different measuring methods led to different momentary rate of photosynthesis. Therefore, the choice of measuring method needs special attention.

Timotein (Phleum pratense ssp. pratense L.) alkuperän vaikutus kylmänkestävyyteen, vernalisaatiovaatimukseen sekä kasvuun ja kehitykseen

Nurmiheinien merkitys maailmanlaajuisesti on merkittävä, sillä noin 69 % maapallon peltopinta-alasta on pysyvää laidunmaata tai niittyä. Suomessa nurmien osuus on noin 29 %, ja tuotanto perustuu pääosin intensiiviseen säilörehuntuotantoon. Yleisin nurmiheinälaji Suomessa on timotei (Phleum pratense ssp. pratense L.). Timotei on talvenkestävä ja soveltuu siksi pohjoisiin kasvuoloihin. Timoteilajikkeita jalostettaessa pohjoista alkuperää olevia vanhempaislinjoja käytetään hyvän talvenkestävyyden varmistamiseksi, eteläisiä tavoiteltaessa nopeaa kasvurytmiä. Ilmaston muutoksen ennustetaan lisäävän erilaisia äärioloja kuten myrskyjä ja sateita. Vuorokauden keskilämpötila nousee ja kasvukausi pidentyy. Lisäksi talvet muuttuvat sateisemmiksi. Muutokset näkyvät erityisesti pohjoisissa kasvuympäristöissä. Tutkimuksessa haluttiinkin selvittää eri alkuperää edustavien timoteilajikkeiden ja linjojen kylmänkestävyyttä, kasvu-, ja kehitysnopeutta sekä vernalisaation vaikutusta. Lisäksi tutkittiin syysviljojen vernalisaatiovasteen mittaamiseen käytettyjen menetelmien soveltuvuutta nurmille. Tutkimukseen kuului kaksivuotinen peltokoe sekä kasvatuskaappikoe. Vernalisaatio nopeutti timotein kasvua ja kehitystä. Tutkimuksen perusteella eteläistä alkuperää olevilla lajikkeilla kasvu- ja kukintavalmius oli olemassa ilman vernalisaatiota. Pohjoisilla lajikkeilla oli suurempi vernalisaatiovaste ja niiden kukkiminen ja kasvu nopeutui vernalisaation myötä. Vernalisaatiolla oli vaikutusta myös kasvuston rakenteeseen. Generatiivisten versojen määrä lisääntyi vernalisaation myötä, kun taas vegetatiivisten versojen määrä väheni. Kylmänkestävyys oli tutkimuksen perusteella riippuvainen syksyn karaistumisjakson pituudesta sekä jakson lämpösummasta (FH-COLD). Korkea keskilämpötila ja lyhyt karaistumisjakso heikensivät kylmänkestävyyttä. Vastaavasti karaistumiskauden lämpötilan ollessa välillä 0 °C:ta ja + 5 °C:ta ja jakson pituuden kasvaessa kylmänkestävyys lisääntyi. Tutkimuksen perusteella vernalisaatiolla oli selvä vaikutus timotein kasvuun ja kehitykseen. Pohjoista alkuperää olevat timoteit reagoivat vernalisaatioon eteläisiä enemmän. Osa pohjoisista linjoista vaati vernalisaation generatiivisten versojen muodostumiseen. Syysviljojen vernalisaatiovasteen mittausmenetelmät soveltuvat osin myös puhtaiden timoteilajikkeiden vernalisaation seurantaan.

The Radiation, snow characteristics and albedo at summit (RASCALS) expedition report

The RASCALS expedition spent over three weeks at the Summit camp research station near the top of the Greenland Ice Sheet during polar summer 2010. During this time, detailed measurements of the physical and optical properties of Arctic perennial snow were carried out concurrently with snow albedo and reflectance measurements. Favorable weather conditions during the campaign enabled the collection of a large dataset on Arctic snow albedo and associated quantities for use in developing and validating remote sensing algorithms for snow albedo using satellites. This report provides a description of the measurements and conditions during the campaign. RASCALS-retkikunnan tehtävä oli tutkia Grönlannin mannerjäätikön lumen fysikaalisia ja optisia ominaisuuksia sekä Auringon valon vuorovaikutusta lumen kanssa. Retikunta vietti hieman yli kolme viikkoa mannerjäätikön keskellä sijaitsevalla Summit Camp-tutkimusasemalla tehden mittauksia. Sääolot suosivat kampanjaa, jonka seurauksena onnistuttiin keräämään laaja ja monipuolinen tietoaineisto mannerjäätikön lumen pintakerroksesta ja eritoten lumen heijastavuuden (albedon)käyttäytymisestä. Aineisto on hyödyllinen kehitettäessä ja varmennettaessa lumen albedon kaukokartoitusmenetelmiä satelliiteilla.