In this thesis, I have studied long shoot performance in the monoecious, deciduous tree Betula pubescens ssp. czerepanovii. In field studies and a common garden experiment, I have a) studied how environmental variations affect the performance of long shoots in mountain birch, and b) described the relationship between long shoot performance and characteristics of the parent long shoot. I have shown that difference in long shoot performance to some extent can be explained by environmental variables such as temperature, precipitation and global radiation the current and previous summer, annual soil and air temperatures, and the length of growing season. For example, a low summer temperature the previous summer had a negative effect on a majority of long shoot characteristics. Variation in shoot characteristics was of the same magnitude along the regional east-western gradient as along the local altitudinal gradient. Variation among individual trees was of the same magnitude as variation among years. Further, long shoot performance was affected by the parent shoot characteristics and reflects that primordia of different organs are formed in the previous summer. On several occasions, freezing damage to mountain birch has been observed on Mt Njulla in northernmost Sweden. Following such damage, fewer but larger leaves emerge. Damages were compensated for with increased number of buds on long shoots produced the same year and one year after damage. Moreover, there were more new long shoots born on short shoots among damaged trees. Dormant buds and short shoots fulfil important functions in a fluctuating environment and as an adaptation to recurring damages of different origin and severity. Differences in the performance among mountain birch saplings grown in a common-garden at Abisko could to a large degree be explained by their origin. Further, saplings from Sweden and from Iceland responded differently to defoliation, and fertilization did not alter the responses to defoliation.

No description available.

No description available.

No description available.

Two decades ago the recruitment of YOY perch (Perca fluviatilis) started to decline along the Swedish east cost of the Baltic Sea. Factors that influence recruitment are e.g. eutrophication that causes habitat losses and overfishing of cod (Gadus morhua) which causes cascading effects in the food web. Filamentous cyanobacterial blooms are often toxic and has increased in the Baltic Sea and its coastal waters. The aim of this field study was to evaluate the effects of salinity and cyanobacterial exposure on fitness related parameters of young of the year (YOY) perch (Perca Fluviatilis) in a natural environment. Our study was performed in the Curonian Lagoon (Lithuania) in August 2009. The lagoon offers a temporary salinity gradient (wind induced influxes from the Baltic Sea) ranging from 7 psu in the north to 0 psu in the south. Submerged enclosures containing YOY perch were set up at three different locations along the salinity gradient in the Lagoon (referred to as North, Middle, South). The duration of the experiment was 21 or 27 days, depending on treatment. Measurements of perch condition were specific growth rate, somatic condition index (SCI) and whole fish lipid and protein content. Average chl a values for the three stations during the experimental time were: north 180 ± 70 µg/l chl a, middle 133 ± 36 µg/l chl a and south 180 ± 52 µg/l chl a. The North and the Middle stations experienced two different salinity influxes reaching a maximum salinity of 6.5 psu at the northern station. The duration of each saline influx was approximately 4-6 days. The saline water did not reach the Southern station at any time. Results show that perch from the southern station were in best condition in terms of specific growth rate and contents of total lipids. Compared to the South the perch condition declined to the Middle station and was lowest at the Northern station which experienced the highest degree of fluctuation in terms of salinity and cyanobacterial exposure. Examination of the abundance of the main food resource at the different stations revealed no statistical differences, which suggest that availability of food was not a factor in explaining the differences in growth.  The results possibly indicate that a changing environment with the potential synergistic negative effects of salinity and cyanobacteria has a higher negative impact on YOY perch condition compared to constantly high concentrations of cyanobacteria.

Common species of freshwater mussels may, like the freshwater pearl mussel (Margaritifera margaritifera) have a drastic decline in number and there is several reasons, like sedimentation, a decline of host fishes, introduction of alien species, nutrition leakages from agriculture and pollutants of medic drugs and poison. Ann Gustavsson made in the year of 2007 a study over rejuventation of freshwater great mussels in nine watersystems and considered that the rejuventation within the populations were all along the line poor. This study orients from her work and points to determine if there is a connection between the poor juventation and pollution of nitrogen and phosphorous from industries and private sanitations. The study was performed with the software program ArcGIS9.2 to take out drainage areas for the concerned habitats and contact was made with the concerned authoritys. When it comes to supervision of private sanitations is it the countys and for industries is it the county administrative board. Most of the countys had a very difficult way to reach their data of the private sanitations and those who had data had great holes in their knowledge in them. The greatest emission of nitrogen was without doubt the industries, but a more even allocation could be seen in the pollution of phosphourus, where the industries and the private sanitations stood for about fifty- fifty of the pollution. The greatest emission of nitrogen and phosphourus happened in Viskan, in the drainage area for Lekvad,there it was a lack of mussels. The species of Anodonta anatina showed a strong positive correlation between emission of nitrogen and phosphourus with the way of juvenile mussels in the population. More studies is need to do in these areas, both when it comes to continuing mapping of rejuventation within the freshwater great mussels in several waters and template value for pollution of nitrogen and phosphourus, that is very doubtful today. Even studies concerning other factors, like predation, host fishes and the influence of poison and medic drugs is needing to do, as it is few studies concerning this today.

När storskaliga och kväveintensiva jordbruk bredde ut sig växte många betesmarker ochängar igen. Detta medförde att hävdberoende växtarter minskade eller helt försvann. Föratt kunna växa och återkolonisera marker behöver många arter olika störningar. En sådanstörning kan vara bränning. Vid bränning ökar ljusinsläppet och även kvävemängden imarken minskar, vilket gynnar de hävdberoende växterna.Detta arbete har undersökt om bränning kan vara ett komplement eller alternativ till beteoch slåtter vid bevarande av den biologiska mångfalden hos växter. I studien inventeradesbrända och orörda kontrollytor på 11 st olika gräsmarker i Östergötland. Dessagräsmarker inkluderar vägrenar, ängar, åkerslänter och naturbetesmarker.Tre olika diversitetsindex användes för att svara på om diversiteten var högre på brändamarkerna. Resultatet visade att diversiteten var högre och artfördelningen var jämnare påde brända ytorna än på kontrollytorna. De arter som är beroende av hävd hade en markantstörre utbredning på de brända markerna än på kontrollytorna. Detta bekräftar hypotesenom att bränning är positivt för hävdberoende växter och att bränning kan vara ettkomplement eller alternativ till bete och slåtter vid bevarande av den biologiskamångfalden av växter i gräsmarker. Den framtida skötseln skulle kunna vara olikakombinationer av bränningar, bete och slåtter.För naturvården kan detta konstaterande få betydelse genom att offentliga och privatamarkägare kan börja bränna fler områden med vetskapen att detta gynnar hävdberoendearter som är hotade. Att bränna marker istället för att slåttra eller beta kan leda till attstörre arealer kan få den skötsel de kräver utan förändringar i den finansiella budgetenhos markägaren. / When the large-scale and nitrogen-intensive agriculture gained land many naturalpastures and meadows started to overgrow. This led to that many species dependent onopen land decreased or totally disappeared. To grow or re-colonize land many speciesneed some form of disturbance. Burning can be one of such disturbances. Burningincrease the light inlet and decrease the amount of nitrogen in the soil. Both of thesechanges will favor the open-land species.The aim of this study was to explore if burning could be a complement or alternative tograzing and mowing for preserving the biological diversity among plants in grasslands.The different kinds of grasslands that were inventoried include hard shoulders, meadows,field slopes and natural pastures. Both burned and control areas were inventoried at 11places. All of them were located in different habitats in Östergötland, Sweden.Three different diversity-indexes have been used to answer the question if diversity washigher on the burned areas than on the control surface. The result showed that both thediversity was higher and the distribution in species spread more evenly on the burnedareas. Species dependent on open land had a notably larger spreading on the burned areasthan on the control areas. This confirms the hypothesis that burning has a positive effecton open-land species and can be a complement or replacement for grazing or mowing inpreserving the biological diversity of plants in grasslands. The future care could bedifferent combinations of burning, grazing and mowing.To the conservation, this knowledge can have a great impact for both state and privatelandowners. Knowing that this method will favor the open-land species, more areas canbe burned. To burn, instead of mowing or grazing, can lead to that larger areas can havethe proper maintenance it requires, without changes in the financial budget of thelandowner.

<p>När storskaliga och kväveintensiva jordbruk bredde ut sig växte många betesmarker ochängar igen. Detta medförde att hävdberoende växtarter minskade eller helt försvann. Föratt kunna växa och återkolonisera marker behöver många arter olika störningar. En sådanstörning kan vara bränning. Vid bränning ökar ljusinsläppet och även kvävemängden imarken minskar, vilket gynnar de hävdberoende växterna.Detta arbete har undersökt om bränning kan vara ett komplement eller alternativ till beteoch slåtter vid bevarande av den biologiska mångfalden hos växter. I studien inventeradesbrända och orörda kontrollytor på 11 st olika gräsmarker i Östergötland. Dessagräsmarker inkluderar vägrenar, ängar, åkerslänter och naturbetesmarker.Tre olika diversitetsindex användes för att svara på om diversiteten var högre på brändamarkerna. Resultatet visade att diversiteten var högre och artfördelningen var jämnare påde brända ytorna än på kontrollytorna. De arter som är beroende av hävd hade en markantstörre utbredning på de brända markerna än på kontrollytorna. Detta bekräftar hypotesenom att bränning är positivt för hävdberoende växter och att bränning kan vara ettkomplement eller alternativ till bete och slåtter vid bevarande av den biologiskamångfalden av växter i gräsmarker. Den framtida skötseln skulle kunna vara olikakombinationer av bränningar, bete och slåtter.För naturvården kan detta konstaterande få betydelse genom att offentliga och privatamarkägare kan börja bränna fler områden med vetskapen att detta gynnar hävdberoendearter som är hotade. Att bränna marker istället för att slåttra eller beta kan leda till attstörre arealer kan få den skötsel de kräver utan förändringar i den finansiella budgetenhos markägaren.</p> / <p>When the large-scale and nitrogen-intensive agriculture gained land many naturalpastures and meadows started to overgrow. This led to that many species dependent onopen land decreased or totally disappeared. To grow or re-colonize land many speciesneed some form of disturbance. Burning can be one of such disturbances. Burningincrease the light inlet and decrease the amount of nitrogen in the soil. Both of thesechanges will favor the open-land species.The aim of this study was to explore if burning could be a complement or alternative tograzing and mowing for preserving the biological diversity among plants in grasslands.The different kinds of grasslands that were inventoried include hard shoulders, meadows,field slopes and natural pastures. Both burned and control areas were inventoried at 11places. All of them were located in different habitats in Östergötland, Sweden.Three different diversity-indexes have been used to answer the question if diversity washigher on the burned areas than on the control surface. The result showed that both thediversity was higher and the distribution in species spread more evenly on the burnedareas. Species dependent on open land had a notably larger spreading on the burned areasthan on the control areas. This confirms the hypothesis that burning has a positive effecton open-land species and can be a complement or replacement for grazing or mowing inpreserving the biological diversity of plants in grasslands. The future care could bedifferent combinations of burning, grazing and mowing.To the conservation, this knowledge can have a great impact for both state and privatelandowners. Knowing that this method will favor the open-land species, more areas canbe burned. To burn, instead of mowing or grazing, can lead to that larger areas can havethe proper maintenance it requires, without changes in the financial budget of thelandowner.</p>

Thesis (M.Sc.)--Memorial University of Newfoundland, 2001. / Includes bibliographical references.

Thesis (M. Arch.)--University of Hong Kong, 1994. / Includes special study report entitled: Aquarium, laboratory and floating structure. Includes bibliographical references.