Effects of living crown reduction on needle element status of Scots pine

A wide range of biotic and abiotic factors, operating over different time perspectives and intensities, cause defoliation and a rapid decrease in the crown size of trees. Scleroderris canker disease [Gremmeniella abietina (Lagerb.) Morelet] has caused widespread crown reduction and tree mortality in Scots pine (Pinus sylvestris L) in forests in Scandinavia during the last three decades. In the 1980's, attempts were made to show, on the basis of the higher foliar N and S concentrations of affected pines in the diseased area, that sulphur and nitrogen deposition predispose trees to G. abietina. Unfortunately, in many studies on defoliated trees, exceptionally high or low needle mineral nutrient concentrations are still often interpreted as one of the causes of tree injury and not, conversely, as the result. In this thesis, three different field experiments, with foliar analysis as the main study method, were conducted in order to asses the possible long-term effects of living crown reduction on the needle nutrient concentrations of Scots pine trees in southern Finland. The crown ratio and length of the living crown were used to estimate the amount of defoliation in the reduced canopies. The material for the partial studies was collected and a total of 968 foliar samples were analysed individually (15-17 elements/sample) on a total of 488 sample trees (140 diseased, 116 pruned and 232 control trees) during the years 1987-1996 in 13 Scots pine stands. All the three experiments of this thesis provided significant evidence that severe, disease-induced defoliation or artificial pruning of the living branches can induce long-lasting nutritional changes in the foliage of the recovering trees under the typical growing conditions for Scots pine. The foliar concentrations of all the 17 mineral nutrients/elements analysed were affected, to a varying degree, by artificial pruning during the following three years. Although Scots pine, as an evergreen conifer, is considered to have low induced chemical responses to defoliation, this study proved experimentally under natural forest conditions that severe artificial pruning or disease-induced defoliation of Scots pine trees may induce biologically significant changes in the concentrations of most of the important macro- and micronutrients, as well as of carbon, in refoliated needles. Concerning the studies in this thesis, I find the results significant in providing new information about the long-term effects of rapid living crown reduction on the foliar nutrient and element status of Scots pine trees. Key words: Foliar analysis, defoliation, needle loss, pruning, nutrients, Pinus sylvestris, Gremmeniella abietina

Phosphorus retention in forest soils and the functioning of buffer zones used in forestry

Phosphorus (P) retention properties of soils typical for boreal forest, i.e. podzolic soil and peat soils, vary significantly, but the range of this variation has not been sufficiently documented. To assess the usefulness of buffer zones used in forestry in removing P from the discharge by chemical sorption in soil, and to estimate the risk of P leaching after forestry operations, more data is needed on soil P retention properties. P retention properties of soils were studied at clear-cut areas, unharvested buffer zones adjoining the clear-cut and at peatland buffer zone areas. Desorption-sorption isotherms were determined for the humus layer, the mineral soil horizons E, B and C of the Podzol profile and for the surface layer peat (0-15 cm) and the subsurface layer peat (15-30 cm). The efficiency of buffer zones in retaining P was studied at six peatland buffer zone areas by adding P-containing solute in the inflow. A tracer study was conducted at one of the buffer zone areas to determine the allocation of the added P in soil and vegetation. Measured sorption or desorption rather than parameter values of fitted sorption equations described P desorption and sorption behaviour in soil. The highest P retention efficiency was in the B horizon and consequently, if contact occurred or was established between the soluble P in the water and the soil B horizon, the risk of P leaching was low. Humus layer was completely incapable of retaining P after clear-cutting. In the buffer zones, the decrease in P retention properties in the humus layer and the low amount of P sorbed by it indicated that the importance of the layer in the functioning of buffer zones is low. The peatland buffer zone areas were efficient in retaining soluble P from inflow. P sorption properties of the peat soil at the buffer zone areas varied largely but the contribution of P sorption in the peat was particularly important during high flow in spring, when the vegetation was not fully developed. Factors contributing to efficient P retention were large buffer size and low hydrological load whereas high hydrological load combined with the formation of preferential flow paths, especially during early spring or late autumn was disadvantageous. However, small buffer zone areas, too, may be efficient in reducing P load.

Phosphorus in agricultural soils of Finland - characterization of reserves and retention in mineral soil profiles

An overwhelming majority of all the research on soil phosphorus (P) has been carried out with soil samples taken from the surface soils only, and our understanding of the forms and the reactions of P at a soil profile scale is based on few observations. In Finland, the interest in studying the P in complete soil profiles has been particularly small because of the lack of tradition in studying soil genesis, morphology, or classification. In this thesis, the P reserves and the retention of orthophosphate phosphorus (PO4-P) were examined in four cultivated mineral soil profiles in Finland (three Inceptisols and one Spodosol). The soils were classified according to the U.S. Soil Taxonomy and soil samples were taken from the genetic horizons in the profiles. The samples were analyzed for total P concentration, Chang and Jackson P fractions, P sorption properties, concentrations of water-extractable P, and for concentrations of oxalate-extractable Al and Fe. Theoretical P sorption capacities and degrees of P saturation were calculated with the data from the oxalate-extractions and the P fractionations. The studied profiles can be divided into sections with clearly differing P characteristics by their master horizons Ap, B and C. The C (or transitional BC) horizons below an approximate depth of 70 cm were dominated by, assumingly apatitic, H2SO4-soluble P. The concentration of total P in the C horizons ranged from 729 to 810 mg kg-1. In the B horizons between the depths of 30 and 70 cm, a significant part of the primary acid-soluble P has been weathered and transformed to secondary P forms. A mean weathering rate of the primary P in the soils was estimated to vary between 230 and 290 g ha-1 year-1. The degrees of P saturation in the B and C horizons were smaller than 7%, and the solubility of PO4-P was negligible. The P conditions in the Ap horizons differed drastically from those in the subsurface horizons. The high concentrations of total P (689-1870 mg kg-1) in the Ap horizons are most likely attributable to long-term cultivation with positive P balances. A significant proportion of the P in the Ap horizons occurred in the NH4F- and NaOH-extractable forms and as organic P. These three P pools, together with the concentrations of oxalate-extractable Al and Fe, seem to control the dynamics of PO4-P in the soils. The degrees of P saturation in the Ap horizons were greater (8-36%) than in the subsurface horizons. This was also reflected in the sorption experiments: Only the Ap horizons were able to maintain elevated PO4-P concentrations in the solution phase − all the subsoil horizons acted as sinks for PO4-P. Most of the available sorption capacity in the soils is located in the B horizons. The results suggest that this capacity could be utilized in reducing the losses of soluble P from excessively fertilized soils by mixing highly sorptive material from the B horizons with the P-enriched surface soil. The drastic differences in the P characteristics observed between adjoining horizons have to be taken into consideration when conducting soil sampling. Sampling of subsoils has to be made according to the genetic horizons or at small depth increments. Otherwise, contrasting materials are likely to be mixed in the same sample; and the results of such samples are not representative of any material present in the studied profile. Air-drying of soil samples was found to alter the results of the sorption experiments and the water extractions. This indicates that the studies on the most labile P forms in soil should be carried out with moist samples.

Characterization of Actinobacteria Degrading and Tolerating Organic Pollutants

Species of the genera Rhodococcus, Gordonia and Mycobacterium are known as degraders of recalcitrant pollutants. These bacteria are good survivors in harsh environments. Due to such properties these organisms are able to occupy a wide range of environmental niches. The members of these taxa have been suggested as tools for biotechnical applications such as bioremediation and biosynthesis. At the same time several of the species are known as opportunistic human pathogens. Therefore, the detailed characterization of any isolate that has potential for biotechnological applications is very important. This thesis deals with several corynebacterial strains originating from different polluted environments: soil, water-damaged indoor walls, and drinking water distribution systems. A polyphasic taxonomic approach was applied for characterization of the isolates. We found that the strains degrading monoaromatic compounds belonged to Rhodococcus opacus, a species that has not been associated with any health problem. The taxonomic position of strain B293, used for many years in degradation research under different names, was clarified. We assigned it to the species Gordonia polyisoprenivorans. This species is classified under European Biohazard grouping 1, meaning that it is not considered a health hazard for humans. However, there are reports of catheter-associated bacteraemia caused by G. polyisoprenivorans. Our results suggested that the ability of the organism to grow on phthalate esters, used as softeners in medical plastics, may be associated with the colonization of catheters and other devices. In this thesis Mycobacterium lentiflavum, a new emerging opportunistic human pathogen, was isolated from biofilms growing in public drinking water distribution systems. Our report on isolation of M. lentiflavum from water supplies is the second report on this species from drinking water systems, which may thus constitute a reservoir of M. lentiflavum. Automated riboprinting was evaluated for its applicability in rapidly identifying environmental mycobacteria. The technique was found useful in the characterization of several species of rapidly and slowly growing environmental mycobacteria. The second aspect of this thesis refers to characterization of the degradation and tolerance power of several R. opacus, M. murale and G. polyisoprenivorans strains. R. opacus GM-14 utilizes a wide range of aromatic substrates, including benzene, 15 different halobenzenes, 18 phenols and 7 benzoates. This study revealed the high tolerance of R. opacus strains toward toxic hydrophobic compounds. R. opacus GM-14 grew in mineral medium to which benzene or monochlorobenzene was added in amounts of 13 or 3 g l-1, respectively. R. opacus GM-29 utilized toluene and benzene for growth. Strain GM-29 grew in mineral medium with 7 g l-1 of liquid toluene or benzene as the sole carbon source, corresponding to aqueous concentrations of 470 and 650 mg l-1, respectively. Most organic solvents, such as toluene and benzene, due to their high level of hydrophobicity, pass through the bacterial membrane, causing its disintegration. In this thesis the mechanisms of adaptation of rhodococci to toxic hydrophobic compounds were investigated. The rhodococcal strains increased the level of saturation of their cellular fatty acids in response to challenge with phenol, chlorophenol, benzene, chlorobenzene or toluene. The results indicated that increase in the saturation level of cellular fatty acids, particularly that in tuberculostearic acid, is part of the adaptation mechanism of strains GM-14 and GM-29 to the presence of toxic hydrophobic compounds.

Associations of gene polymorphisms and nutrition with calcium homeostasis and bone mineral density : Studies on skeletal nutrigenetics

Heredity explains a major part of the variation in calcium homeostasis and bone strength, and the susceptibility to osteoporosis is polygenetically regulated. Bone phenotype results from the interplay between lifestyle and genes, and several nutritional factors modulate bone health throughout life. Thus, nutrigenetics examining the genetic variation in nutrient intake and homeostatic control is an important research area in the etiology of osteoporosis. Despite continuing progress in the search for candidate genes for osteoporosis, the results thus far have been inconclusive. The main objective of this thesis was to investigate the associations of lactase, vitamin D receptor (VDR), calcium sensing receptor (CaSR) and parathyroid hormone (PTH) gene polymorphisms and lifestyle factors and their interactions with bone health in Finns at varying stages of the skeletal life span. Markers of calcium homeostasis and bone remodelling were measured from blood and urine samples. Bone strength was measured at peripheral and central bone sites. Lifestyle factors were assessed with questionnaires and interviews. Genetic lactase non-persistence (the C/C-13910 genotype) was associated with lower consumption of milk from childhood, predisposing females in particular to inadequate calcium intake. Consumption of low-lactose milk and milk products was shown to decrease the risk for inadequate calcium intake. In young adulthood, bone loss was more common in males than in females. Males with the lactase C/C-13910 genotype may be more susceptible to bone loss than males with the other lactase genotypes, although calcium intake predicts changes in bone mass more than the lactase genotype. The BsmI and FokI polymorphisms of the VDR gene were associated with bone mass in growing adolescents, but the associations weakened with age. In young adults, the A986S polymorphism of the calcium sensing receptor gene was associated with serum ionized calcium concentrations, and the BstBI polymorphism of the parathyroid gene was related to bone strength. The FokI polymorphism and sodium intake showed an interaction effect on urinary calcium excretion. A novel gene-gene interaction between the VDR FokI and PTH BstBI gene polymorphisms was found in the regulation of PTH secretion and urinary calcium excretion. Further research should be carried out with more number of Finns at varying stages of the skeletal life span and more detailed measurements of bone strength. Research should concern mechanisms by which genetic variants affect calcium homeostasis and bone strength, and the role of diet-gene and gene-gene interactions in the pathogenesis of osteoporosis.

Chemical and source characterisation of size-segregated urban air particulate matter

Recent epidemiological studies have shown a consistent association of the mass concentration of urban air thoracic (PM10) and fine (PM2.5) particles with mortality and morbidity among cardiorespiratory patients. However, the chemical characteristics of different particulate size ranges and the biological mechanisms responsible for these adverse health effects are not well known. The principal aims of this thesis were to validate a high volume cascade impactor (HVCI) for the collection of particulate matter for physicochemical and toxicological studies, and to make an in-depth chemical and source characterisation of samples collected during different pollution situations. The particulate samples were collected with the HVCI, virtual impactors and a Berner low pressure impactor in six European cities: Helsinki, Duisburg, Prague, Amsterdam, Barcelona and Athens. The samples were analysed for particle mass, common ions, total and water-soluble elements as well as elemental and organic carbon. Laboratory calibration and field comparisons indicated that the HVCI can provide a unique large capacity, high efficiency sampling of size-segregated aerosol particles. The cutoff sizes of the recommended HVCI configuration were 2.4, 0.9 and 0.2 μm. The HVCI mass concentrations were in a good agreement with the reference methods, but the chemical composition of especially the fine particulate samples showed some differences. This implies that the chemical characterization of the exposure variable in toxicological studies needs to be done from the same HVCI samples as used in cell and animal studies. The data from parallel, low volume reference samplers provide valuable additional information for chemical mass closure and source assessment. The major components of PM2.5 in the virtual impactor samples were carbonaceous compounds, secondary inorganic ions and sea salt, whereas those of coarse particles (PM2.5-10) were soil-derived compounds, carbonaceous compounds, sea salt and nitrate. The major and minor components together accounted for 77-106% and 77-96% of the gravimetrically-measured masses of fine and coarse particles, respectively. Relatively large differences between sampling campaigns were observed in the organic carbon content of the PM2.5 samples as well as the mineral composition of the PM2.5-10 samples. A source assessment based on chemical tracers suggested clear differences in the dominant sources (e.g. traffic, residential heating with solid fuels, metal industry plants, regional or long-range transport) between the sampling campaigns. In summary, the field campaigns exhibited different profiles with regard to particulate sources, size distribution and chemical composition, thus, providing a highly useful setup for toxicological studies on the size-segregated HVCI samples.

Remote sensing of leaf area index: enhanced retrieval from close-range and remotely sensed optical observations

A wide range of models used in agriculture, ecology, carbon cycling, climate and other related studies require information on the amount of leaf material present in a given environment to correctly represent radiation, heat, momentum, water, and various gas exchanges with the overlying atmosphere or the underlying soil. Leaf area index (LAI) thus often features as a critical land surface variable in parameterisations of global and regional climate models, e.g., radiation uptake, precipitation interception, energy conversion, gas exchange and momentum, as all areas are substantially determined by the vegetation surface. Optical wavelengths of remote sensing are the common electromagnetic regions used for LAI estimations and generally for vegetation studies. The main purpose of this dissertation was to enhance the determination of LAI using close-range remote sensing (hemispherical photography), airborne remote sensing (high resolution colour and colour infrared imagery), and satellite remote sensing (high resolution SPOT 5 HRG imagery) optical observations. The commonly used light extinction models are applied at all levels of optical observations. For the sake of comparative analysis, LAI was further determined using statistical relationships between spectral vegetation index (SVI) and ground based LAI. The study areas of this dissertation focus on two regions, one located in Taita Hills, South-East Kenya characterised by tropical cloud forest and exotic plantations, and the other in Gatineau Park, Southern Quebec, Canada dominated by temperate hardwood forest. The sampling procedure of sky map of gap fraction and size from hemispherical photographs was proven to be one of the most crucial steps in the accurate determination of LAI. LAI and clumping index estimates were significantly affected by the variation of the size of sky segments for given zenith angle ranges. On sloping ground, gap fraction and size distributions present strong upslope/downslope asymmetry of foliage elements, and thus the correction and the sensitivity analysis for both LAI and clumping index computations were demonstrated. Several SVIs can be used for LAI mapping using empirical regression analysis provided that the sensitivities of SVIs at varying ranges of LAI are large enough. Large scale LAI inversion algorithms were demonstrated and were proven to be a considerably efficient alternative approach for LAI mapping. LAI can be estimated nonparametrically from the information contained solely in the remotely sensed dataset given that the upper-end (saturated SVI) value is accurately determined. However, further study is still required to devise a methodology as well as instrumentation to retrieve on-ground green leaf area index . Subsequently, the large scale LAI inversion algorithms presented in this work can be precisely validated. Finally, based on literature review and this dissertation, potential future research prospects and directions were recommended.

Characterisation and source identification of pollution episodes caused by long-range transported aerosols

Aerosol particles can cause detrimental environmental and health effects. The particles and their precursor gases are emitted from various anthropogenic and natural sources. It is important to know the origin and properties of aerosols to efficiently reduce their harmful effects. The diameter of aerosol particles (Dp) varies between ~0.001 and ~100 μm. Fine particles (PM2.5: Dp < 2.5 μm) are especially interesting because they are the most harmful and can be transported over long distances. The aim of this thesis is to study the impact on air quality by pollution episodes of long-range transported aerosols affecting the composition of the boundary-layer atmosphere in remote and relatively unpolluted regions of the world. The sources and physicochemical properties of aerosols were investigated in detail, based on various measurements (1) in southern Finland during selected long-range transport (LRT) pollution episodes and unpolluted periods and (2) over the Atlantic Ocean between Europe and Antarctica during a voyage. Furthermore, the frequency of LRT pollution episodes of fine particles in southern Finland was investigated over a period of 8 years, using long-term air quality monitoring data. In southern Finland, the annual mean PM2.5 mass concentrations were low but LRT caused high peaks of daily mean concentrations every year. At an urban background site in Helsinki, the updated WHO guideline value (24-h PM2.5 mean 25 μg/m3) was exceeded during 1-7 LRT episodes each year during 1999-2006. The daily mean concentrations varied between 25 and 49 μg/m3 during the episodes, which was 3-6 times higher than the mean concentration in the long term. The in-depth studies of selected LRT episodes in southern Finland revealed that biomass burning in agricultural fields and wildfires, occurring mainly in Eastern Europe, deteriorated air quality on a continental scale. The strongest LRT episodes of fine particles resulted from open biomass-burning fires but the emissions from other anthropogenic sources in Eastern Europe also caused significant LRT episodes. Particle mass and number concentrations increased strongly in the accumulation mode (Dp ~ 0.09-1 μm) during the LRT episodes. However, the concentrations of smaller particles (Dp < 0.09 μm) remained low or even decreased due to the uptake of vapours and molecular clusters by LRT particles. The chemical analysis of individual particles showed that the proportions of several anthropogenic particle types increased (e.g. tar balls, metal oxides/hydroxides, spherical silicate fly ash particles and various calcium-rich particles) in southern Finland during an LRT episode, when aerosols originated from the polluted regions of Eastern Europe and some open biomass-burning smoke was also brought in by LRT. During unpolluted periods when air masses arrived from the north, the proportions of marine aerosols increased. In unpolluted rural regions of southern Finland, both accumulation mode particles and small-sized (Dp ~ 1-3 μm) coarse mode particles originated mostly from LRT. However, the composition of particles was totally different in these size fractions. In both size fractions, strong internal mixing of chemical components was typical for LRT particles. Thus, the aging of particles has significant impacts on their chemical, hygroscopic and optical properties, which can largely alter the environmental and health effects of LRT aerosols. Over the Atlantic Ocean, the individual particle composition of small-sized (Dp ~ 1-3 μm) coarse mode particles was affected by continental aerosol plumes to distances of at least 100-1000 km from the coast (e.g. pollutants from industrialized Europe, desert dust from the Sahara and biomass-burning aerosols near the Gulf of Guinea). The rate of chloride depletion from sea-salt particles was high near the coasts of Europe and Africa when air masses arrived from polluted continental regions. Thus, the LRT of continental aerosols had significant impacts on the composition of the marine boundary-layer atmosphere and seawater. In conclusion, integration of the results obtained using different measurement techniques captured the large spatial and temporal variability of aerosols as observed at terrestrial and marine sites, and assisted in establishing the causal link between land-bound emissions, LRT and air quality.

Population dynamics of blue mussels in a variable environment at the edge of their range

Spatial and temporal variation in the abundance of species can often be ascribed to spatial and temporal variation in the surrounding environment. Knowledge of how biotic and abiotic factors operate over different spatial and temporal scales in determining distribution, abundance, and structure of populations lies at the heart of ecology. The major part of the current ecological theory stems from studies carried out in central parts of the distributional range of species, whereas knowledge of how marginal populations function is inadequate. Understanding how marginal populations, living at the edge of their range, function is however in a key position to advance ecology and evolutionary biology as scientific disciplines. My thesis focuses on the factors affecting dynamics of marginal populations of blue mussels (Mytilus edulis) living close to their tolerance limits with regard to salinity. The thesis aims to highlight the dynamics at the edge of the range and contrast these with dynamics in more central parts of the range in order to understand the potential interplay between the central and the marginal part in the focal system. The objectives of the thesis are approached by studies on: (1) factors affecting regional patterns of the species, (2) long-term temporal dynamics of the focal species spaced along a regional salinity gradient, (3) selective predation by increasing populations of roach (Rutilus rutilus) when feeding on their main food item, the blue mussel, (4) the primary and secondary effects of local wave exposure gradients and (5) the role of small-scale habitat heterogeneity as determinants of large-scale pattern. The thesis shows that populations of blue mussels are largely determined by large scale changes in sea water salinity, affecting mainly recruitment success and longevity of local populations. In opposite to the traditional view, the thesis strongly indicate that vertebrate predators strongly affect abundance and size structure of blue mussel populations, and that the role of these predators increases towards the margin where populations are increasingly top-down controlled. The thesis also indicates that the positive role of biogenic habitat modifiers increases towards the marginal areas, where populations of blue mussels are largely recruitment limited. Finally, the thesis shows that local blue mussel populations are strongly dependent on high water turbulence, and therefore, dense populations are constrained to offshore habitats. Finally, the thesis suggests that ongoing sedimentation of rocky shores is detrimental for the species, affecting recruitment success and post-recruit survival, pushing stable mussel beds towards offshore areas. Ongoing large scale changes in the Baltic Sea, especially dilution processes with attendant effects, are predicted to substantially contract the distributional range of the mussel, but also affect more central populations. The thesis shows that in order to understand the functioning of marginal populations, research should (1) strive for multi-scale approaches in order to link ecosystem patterns with ecosystem processes, and (2) challenge the prevailing tenets that origin from research carried out in central areas that may not be valid at the edge.

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.

Country-scale carbon accounting of the vegetation and mineral soils of Finland

The increase in global temperature has been attributed to increased atmospheric concentrations of greenhouse gases (GHG), mainly that of CO2. The threat of severe and complex socio-economic and ecological implications of climate change have initiated an international process that aims to reduce emissions, to increase C sinks, and to protect existing C reservoirs. The famous Kyoto protocol is an offspring of this process. The Kyoto protocol and its accords state that signatory countries need to monitor their forest C pools, and to follow the guidelines set by the IPCC in the preparation, reporting and quality assessment of the C pool change estimates. The aims of this thesis were i) to estimate the changes in carbon stocks vegetation and soil in the forests in Finnish forests from 1922 to 2004, ii) to evaluate the applied methodology by using empirical data, iii) to assess the reliability of the estimates by means of uncertainty analysis, iv) to assess the effect of forest C sinks on the reliability of the entire national GHG inventory, and finally, v) to present an application of model-based stratification to a large-scale sampling design of soil C stock changes. The applied methodology builds on the forest inventory measured data (or modelled stand data), and uses statistical modelling to predict biomasses and litter productions, as well as a dynamic soil C model to predict the decomposition of litter. The mean vegetation C sink of Finnish forests from 1922 to 2004 was 3.3 Tg C a-1, and in soil was 0.7 Tg C a-1. Soil is slowly accumulating C as a consequence of increased growing stock and unsaturated soil C stocks in relation to current detritus input to soil that is higher than in the beginning of the period. Annual estimates of vegetation and soil C stock changes fluctuated considerably during the period, were frequently opposite (e.g. vegetation was a sink but soil was a source). The inclusion of vegetation sinks into the national GHG inventory of 2003 increased its uncertainty from between -4% and 9% to ± 19% (95% CI), and further inclusion of upland mineral soils increased it to ± 24%. The uncertainties of annual sinks can be reduced most efficiently by concentrating on the quality of the model input data. Despite the decreased precision of the national GHG inventory, the inclusion of uncertain sinks improves its accuracy due to the larger sectoral coverage of the inventory. If the national soil sink estimates were prepared by repeated soil sampling of model-stratified sample plots, the uncertainties would be accounted for in the stratum formation and sample allocation. Otherwise, the increases of sampling efficiency by stratification remain smaller. The highly variable and frequently opposite annual changes in ecosystem C pools imply the importance of full ecosystem C accounting. If forest C sink estimates will be used in practice average sink estimates seem a more reasonable basis than the annual estimates. This is due to the fact that annual forest sinks vary considerably and annual estimates are uncertain, and they have severe consequences for the reliability of the total national GHG balance. The estimation of average sinks should still be based on annual or even more frequent data due to the non-linear decomposition process that is influenced by the annual climate. The methodology used in this study to predict forest C sinks can be transferred to other countries with some modifications. The ultimate verification of sink estimates should be based on comparison to empirical data, in which case the model-based stratification presented in this study can serve to improve the efficiency of the sampling design.

Bone health and vitamin D status in children with motor disability and adults with intellectual disability

Osteoporosis is not only a disease of the elderly, but is increasingly diagnosed in chronically ill children. Children with severe motor disabilities, such as cerebral palsy (CP), have many risk factors for osteoporosis. Adults with intellectual disability (ID) are also prone to low bone mineral density (BMD) and increased fractures. This study was carried out to identify risk factors for low BMD and osteoporosis in children with severe motor disability and in adults with ID. In this study 59 children with severe motor disability, ranging in age from 5 to 16 years were evaluated. Lumbar spine BMD was measured with dual-energy x-ray absorptiometry. BMD values were corrected for bone size by calculating bone mineral apparent density (BMAD), and for bone age. The values were transformed into Z-scores by comparison with normative data. Spinal radiographs were assessed for vertebral morphology. Blood samples were obtained for biochemical parameters. Parents were requested to keep a food diary for three days. The median daily energy and nutrient intakes were calculated. Fractures were common; 17% of the children had sustained peripheral fractures and 25% had compression fractures. BMD was low in children; the median spinal BMAD Z-score was -1.0 (range -5.0 – +2.0) and the BMAD Z-score <-2.0 in 20% of the children. Low BMAD Z-score and hypercalciuria were significant risk factors for fractures. In children with motor disability, calcium intakes were sufficient, while total energy and vitamin D intakes were not. In the vitamin D intervention studies, 44 children and adolescents with severe motor disability and 138 adults with ID were studied. After baseline blood samples, the children were divided into two groups; those in the treatment group received 1000 IU peroral vitamin D3 five days a week for 10 weeks, and subjects in the control group continued with their normal diet. Adults with ID were allocated to receive either 800 IU peroral vitamin D3 daily for six months or a single intramuscular injection of 150 000 IU D3. Blood samples were obtained at baseline and after treatment. Serum concentrations of 25-OH-vitamin D (S-25-OHD) were low in all subgroups before vitamin D intervention: in almost 60% of children and in 77% of adults the S-25-OHD concentration was below 50 nmol/L, indicating vitamin D insufficiency. After vitamin D intervention, 19% of children and 42% adults who received vitamin D perorally and 12% of adults who received vitamin D intramuscularly had optimal S-25-OHD (>80 nmol/L). This study demonstrated that low BMD and peripheral and spinal fractures are common in children with severe motor disabilities. Vitamin D status was suboptimal in the majority of children with motor disability and adults with ID. Vitamin D insufficiency can be corrected with vitamin D supplements; the peroral dose should be at least 800 IU per day.