<p>Diss. Umeå : Univ.</p>

Diss. (sammanfattning) Linköping : Linköpings universitet, 2007. / Härtill 4 uppsatser.

Diss. (sammanfattning) Uppsala : Uppsala universitet, 2009. / Härtill 4 uppsatser.

For ectothermic organisms, both terrestrial and aquatic, the environmental temperature is imperative for their metabolic processes and finally for their growth and fitness. Previous research have shown that aquatic ectothermic organisms through the process of sun basking, were able to increase their body temperature in comparison with the one of the surrounding water. During this project I studied the possibility that organisms through the combination of sun basking and schooling behaviour can rise the temperature of their surrounding water and as a consequence create their own thermally favourable microhabitat. During this project I investigated whether and how the colour and size of the school’s individuals, the size of the school and the clarity of the water may influence the school effect on water temperature by a series of manipulation experiments. The project took place in the laboratory, where I used physical models of different sizes, colours and densities as proxies for fish. The models were submerged in aquaria with clean water, water that was coloured with dye, or water that was coloured with algae and exposed to artificial light. The results showed that the colour and density of the schools in the aquaria influenced the school effect in the aquaria. Last but notleast, the colour of the water, either artificial (dye) or natural (algae), was an important factor in the rate of the rising temperature in the aquaria by increasing it more rapidly and by reducing the schooling effect from the tubes.

Eutrofiering av akvatiska miljöer är idag ett stort miljöproblem och åtgärder för att minska eutrofiering av sjöar och vattendrag är av hög prioritet i Sveriges miljöarbete. Eutrofiering leder till negativa följder som försämrad vattenkvalitet, sänkt biodiversitet och försämrade rekreationsmöjligheter. Delvis orsakas dessa negativa följder av hög biomassa hos fytoplankton, vilken i akvatiska miljöer är starkt kopplad till tillgång av näringsämnet fosfor. Syftet med denna studie var att undersöka om kalkning under våren kunde minska fosforhalten i sjön Tåkern i Östergötlands län. Studien genomfördes i april 2015 då effekter av kalkning till pH 10 med kalkstensmjöl (CaCO3) samt släckt kalk (Ca(OH)2) undersöktes genom ett mesokosm-försök. Kalktillsatsen förväntades leda till utfällning av kalcit till vilken fosfor kan adsorberas. De variabler som undersöktes var totalfosfor (TP), partikulärt fosfor (PP), löst reaktiv fosfor (MRP) och kompletterande vattenkemi. Resultaten visade att kalkningen inte hade betydande påverkan på varken MRP (under detektionsgränsen 2 µg L-1), TP eller PP. Det fanns en tendens till påverkan på klorofyll a (fytoplanktonbiomassa), effekterna var dock övergående. Den uteblivna effekten var sannolikt en följd av de låga halterna av MRP. En ökning av TP och PP observerades vilken sannolikt orsakades av en kort period med hård vind då kraftig omblandning skedde. Ökningen kan orsakats av resuspendering av partikulärt bunden fosfor från sediment. Resultaten av denna studie visade att kalkning vid ett enda tillfälle inte är en lämplig metod för att kontrollera fosforhalten i Tåkern. De låga halter MRP som observerats indikerar att upprepade kalkningar inte heller skulle ge önskad effekt. / One of the major current environmental issues is eutrophication of aquatic environments. Measures to reduce eutrophication of lakes and streams are of high priority in Sweden. There are several negative implications of eutrophication such as lowered water quality, reduced biodiversity and loss of recreational values. These negative effects can be correlated to high phosphorus concentrations. The purpose of this study was to investigate the possibility of reducing the amount of available phosphorus during spring using liming in Lake Tåkern in southern Sweden. The study was conducted in April of 2015 in five mesocosms, three were treated with a mixture of limestone powder (CaCO3) and slaked lime (Ca(OH)2) to pH and two were untreated (controls). The aim of the liming was to precipitate calcite, to which phosphorus adsorbs. The variables used to document effects of liming include particulate phosphorus (PP), total phosphorus (TP), soluble reactive phosphorus (SRP) and complementary water chemistry. In addition to this experiment, samples of TP from a previous mesokosm experiment in July 2014 were analysed for comparison. Results showed no significant effects of liming on either PP, TP or SRP. The lack of effects from liming was most likely a result of low concentration of SRP in Lake Tåkern. Conclusions from this study were that liming at one occasion is not suitable for control of phosphorus concentration, the low observed concentrations of SRP over a longer period also indicates that repeated liming’s would not affect phosphorus concentration in Lake Tåkern.

In this essay two young alkaline fens in Rustsäters limestone quarry are compared with two old genuine alkaline fens in the browsed wildlife preserve of Österplana hed and vall, in the municipality of Götene in Sweden. The compound and occurrence of plants in the two sites Brottet övre (Upper Quarry) and Brottet nedre (Lower Quarry) are the starting-point of comparison and discussions of how the sites can develop into genuine alkaline fens and what actions of management that would serve that purpose. Alkaline fens are important ecologically rich habitats that are threatened by diking and increased incidence of high growing herbs, bushes and trees. In Sweden there are examples of projects where historically alkaline fens have been restored by removing the upper vegetation and soil layer. The flora and fauna representative of alkaline fens re-establish in four to five years. It takes 20-30 years before the restored area looks like genuine alkaline fens. Knowledge of how new alkaline fens establish is inadequate. Species typical for alkaline fens was noted in all of the inventoried locales. Some species that signal a risk of unwanted high vegetation, that may shadow the other species, was registered in the quarry. This is an indication of that management and clearing may be necessary as well as further inventories in the two newer alkaline fens habitat in the quarry. / I arbetet jämförs två nyare rikkärrsmiljöer i ett nedlagt kalkstensbrott, Rustsäters stenbrott, med två äldre genuina rikkärr i ett hävdat naturreservat, Österplana hed och vall, på Kinnekulle i Götene kommun. Kärlväxternas artsammansättning och frekvens i lokalerna i stenbrottet, Brottet övre och Brottet nedre samt referenslokalerna Österplana norra och Österplana södra, är utgångspunkt för jämförelser och diskussion kring hur succession mot rikkärr kan underlättas - samt vilka skötselåtgärder som kan vara aktuella för detta syfte. Rikkärr är en prioriterad naturtyp som hyser karaktäristiska och specialiserade kärlväxter, mossor och mollusker. Största hotet idag är habitatförlust till följd av dikning eller igenväxning. I Sverige finns några exempel där man återskapat historiska rikkärr genom borthyvling av matjord. Inventeringar visar att en basal rikkärrsflora finns efter fyra till fem år, men det tar mellan 20-30 år innan det nyskapade kärret ses som ett genuint rikkärr. Kunskap om hur rikkärr etableras på helt ny mark är bristfällig.Under arbetet noterades karaktärsarter för rikkärr i samtliga lokaler. Arter som indikerar igenväxning noterades främst i lokalerna i stenbrottet. Deras förekomst ses som en indikation på att båda lokalerna i stenbrottet på sikt kan behöva röjas och eventuellt hävdas. Ytterligare inventeringar och vassröjning ges som förslag på skötselåtgärder.

Several studies indicate a long-term decline in the numbers of voles in northern Fennoscandia. Altered land use and forest management practices have been proposed as possible causes of the decline. This doctorial thesis aimed to identify, on different spatial scales, landscape patterns that are important for the abundance of small mammals and that might be related to the decline. General trends and aspects of spatial habitat modelling were reviewed. Trapping data from three large extent monitoring programs were related to habitat factors on different spatial scales. For these analyses, a broad range of statistical and GIS (geographic information system) related methods was applied. On the microscale (trapping station, extent <= 10 m) and mesoscale (transect, length 90 m), structural habitat factors such as coarse and fine woody debris, umbrella vegetation and structural complexity of the forest floor were identified as important factors influencing small mammal abundance. Small mammal densities were related to the percentage landcover of vegetation types on the micro-, meso-, macro- (subarea/landscape, 1 x 1, 2.5 x 2.5 and 2 x 5 km) and regional scale (overall study area, 20 x 20 - 80 x 80 km). The spatial continuity (non- fragmentation) of old-growth pine forest patches on the landscape scale was positively related to the abundance of C. rufocanus, the species that showed the most pronounced long-term decline in numbers. The results of this thesis strongly suggest that altered land use might indeed be involved in the decline in numbers of voles in managed forest areas in northern Fennoscandia. To reveal and test responses of small mammals to changes in landscape patterns in more detail, this work proposes further application of large scale approaches. These approaches, e.g. the GIS-based prediction of the areas with currently high abundance of C. rufocanus can be tested by field sampling of the type applied in this thesis. Such approaches should consider the key aspects identified in the reviews on GIS-based habitat modelling, e.g. reconciling the scale of the population dynamics of small mammals with the scale (resolution and extent) of the input data, the application of different modelling approaches and the performance of sensitivity analysis. / Godkänd; 2003; 20061106 (haneit)

In a climate change perspective increased precipitation and temperature are expected which should influence the coastal microbial food web. Precipitation will have a strong impact on river flow and thereby increase the carbon input to the coastal zone as well as lowering the marine salinity by dilution with freshwater. Simultaneously temperature may increase by 2-5 °C, potentially influencing e.g. metabolic processes. Consequences of this have been evaluated in this thesis with focus on microbial respiration in paper II and IV. A temperature increase of 3 °C will have a marked effect on microbial respiration rates in the coastal zone. The effect of temperature on microbial respiration showed a median Q10 value of 25 with markedly higher values during winter conditions (around 0°C). These Q10 values are several-fold higher than found in oceanic environments. The conclusion was in accordance with a consistent temperature limitation of microbial respiration during an annual field study, however, shifting to DOC limitation at the elevated temperature. Neither bacterial production nor phytoplankton production showed a consistent temperature effect, suggesting that the biomass production at the base of the food web is less sensitive to a temperature increase. Results from both a field study and a fully factorial microcosm experiment supported the conclusion. Our results suggested that areas dealing with hypoxia today will most likely expand in the future, due to increased respiration caused by higher temperatures and larger riverine output of dissolved organic carbon.  Pelagic respiration measurements in the sea are relatively scarce in the literature, mainly due to the lack of sufficiently good and user friendly techniques. New methods such as the dynamic luminescence quenching technique for oxygen concentration have been developed. This makes it possible to obtain continuous measurements of oxygen in an enclosed vial. Two different commercially available systems based on the dynamic luminescence quenching technique were evaluated from the aspect of precision, accuracy and detection limit when applied to respiration measurements in natural pelagic samples. The Optode setup in paper III showed a practical detection limit of 0.30 mmol m-3 d-1, which can be applied to measure respiration in productive coastal waters (used in paper IV). This included development of a stopper where the sensor was attached, stringent temperature control, proper stirring and compensation for an observed system drift. For controlled laboratory experiments with organisms smaller than 1 µm the Sensor Dish Reader (paper I) has sufficient detection limit of (4.8 mmol m-3 d-1). This required a stringent temperature control and manual temperature correction. The Sensor Dish Reader gives the opportunity to perform multiple treatments at low cost (used in paper II), but the precision is too low for field studies due to the between ampule variation. / Östersjön är ett brackvatten hav som sträcker sig från Bottenviken i norr till de danska sunden i söder och omsluts av en landmassa som representeras av nio länder. Denna miljö är på många sett unik genom stor sötvattenpåverkan och litet utbyte med världshaven (30 års omsättningstid). Östersjön utsätts framförallt för tillförsel av ämnen från såväl naturliga som antropogena aktiviteter. Något som ofta uppmärksammas är problem med syrefria områden och döda havsbottnar. Detta anses påverkas av både klimatförändringar och övergödning. En av de biologiska prosesser som påverkar syresituationen i haven är respiration, syreförbrukning, som utförs av de flesta levande organismerna i Östersjön. Den här avhandlingen presenterar resultat på hur bakteriers syreförbrukning påverkas av de förändringar vi förväntar oss i vårt klimat i framtiden. Det är framförallt ökad temperatur och ökat vattenflöde i våra floder som i sin tur leder till snabbare omsättning och tillförsel av näring åt bakteriesamhället. Resultaten från artiklarna II och IV visar att den potentiella temperaturökningen som väntas skulle öka syreförbrukningen i kustnära områden. Den blir extra stor i kustområden, troligen på grund av stor tillgång på organiskt material från älvarna. Även den högre tillförseln av näringsämnen kan ökan syreförbrukningen enligt artikel II. De områden som idag är syrefattiga kommer på grund av detta att expandera, framförallt längs kusterna där nya områden kan uppstå. Eventuellt kan det vara en förklaring till den ökande ytan av syrefria bottnar i i Östersjön och världshaven. För att kunna utföra mätningar av syreförbrukning krävs väldigt precisa och gärna användarvänliga metoder som lätt kan tillämpas i fält. I avhandlingen presenteras hur två olika mätmetoder optimeras för att göra tillförlitliga förbrukningsmätningar av syre. Ny teknik gör att syrehalten kan mätas med en ljusbaserad metod som skiljer sig från dagens kemiska bl.a. genom att resultaten kan följas löpande på en dator. De båda metoderna kräver en väldigt precis temperaturkontroll. Optod uppsättningen presenterad i artikel III innefattaer en volym på 1 liter och organismer upp till en storlek på 50 μm omfattas i den uppmäta syreföbrukningen. Denna metod rekommenderas fö fätmäningar, och anvädes föfätmäningar i Artikel IV. I utvecklingen ingick utformning av en kork fö att montera optod-sensorn i. I artikel I presenteras en utrustning som baseras påen mindre volym (5 ml) vilket innebä att endast mäningar påbakterier och organismer mindre ä 1 μm kan anses tillfölitliga. Detta i kombination med viss variation mellan mäflaskor gö att den framföallt rekomenderas fö anvädning i laboratoriemiljö Det systemet anvädes fö mäningarna av syreföbrukning i laboratorieexperimentet som presenteras i artikel II.

Forest regeneration in the form of successful seedling establishment is a key factor for the persistence of a healthy forest ecosystem. Tree seedlings grow in a complex environment shaped by over- and understory and competition for light, nutrients and water. Not much research has been done on how climate change is impacting on seedling performance through direct and indirect warming effects including possible interactions with the growth environment i.e. understory vegetation. To elucidate these, seedlings of B. pubescens, P. sylvestris and P. abies were planted into a full-factorial experiment consisting of randomly assigned plant functional group (moss) removal in combination with passive warming (open-top chambers [OTCs]) along a post-fire chronosequence. Each seedling’s survival and growth had been surveyed over a period of three years (not as part of this thesis). At the end of the experiment, growth assessment in terms of biomass determination was done, by harvesting selected individuals. Growth has been found to be species-specific but without evidence of a direct or interactive warming effect. The survival analysis highlights that mosses promoted a positive warming effect on survival in the young and intermediate successional stages regardless of seedling species. In the old successional stage warming reduced survival regardless of moss presence explicitly for B. pubescens and P. sylvestris. If, as anticipated, climate change induces a shift toward younger forest stands by altering the fire frequency and climate warms, moss cover can therefore become a critical factor for seedling survival in the boreal forest.

Many of our crops as well as many of the wild plants around us are dependent on pollination by insects (Insecta) to produce fruit. The perhaps most important group of pollinating insects are bees (Apidae) and especially solitary bees. Solitary bees are declining globally and are therefore important to safeguard and to learn more about, especially which factors that affect them. This study explores the effect of vegetation height and flower distribution on the abundance and diversity of solitary bees in and around limestone quarries. Inventories were done on Gotland, Sweden. Limestone quarries have earlier been found to be an important habitat for many species of solitary bees. Flower distribution was found to significantly influence the diversity of solitary bees and the abundance of solitary bees. An increase in vegetation &gt;5cm had no significant effect on the diversity of solitary bees nor on the abundance of solitary bees.