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  • 101.
    Olsson, Katarina
    et al.
    Umeå universitet, Teknisk-naturvetenskaplig fakultet, Ekologi och geovetenskap.
    Ågren, Jon
    Adaptive population differentiation across Europe in the perennial herb Lythrum salicaria.Artikel i tidskrift (Refereegranskat)
  • 102.
    Olsson, Katarina
    et al.
    Umeå universitet, Teknisk-naturvetenskaplig fakultet, Ekologi och geovetenskap.
    Ågren, Jon
    Latitudinal population differentiation in phenology, life history and flower morphology in the perennial herb Lythrum salicaria.2002Ingår i: Journal of Evolutionary Biology, Vol. 15, s. 983-996Artikel i tidskrift (Refereegranskat)
  • 103.
    Olsson, Katarina
    et al.
    Umeå universitet, Teknisk-naturvetenskaplig fakultet, Ekologi och geovetenskap.
    Ågren, Jon
    Phenotypic selection on phenology and morphology and predicted evolutionary response in Lythrum salicaria.Manuskript (Övrigt vetenskapligt)
  • 104.
    Palmqvist, K
    et al.
    Umeå universitet, Teknisk-naturvetenskaplig fakultet, Ekologi, miljö och geovetenskap.
    Dahlman, L
    Umeå universitet, Teknisk-naturvetenskaplig fakultet, Ekologi och geovetenskap.
    Valladares, F
    Tehler, A
    Sanches, LG
    Mattsson, J-E
    CO2 exchange and thallus nitrogen across 75 contrasting lichen associations from different climate zones.2002Ingår i: Oecologia, ISSN 0029-8549, Vol. 133, s. 295-306Artikel i tidskrift (Refereegranskat)
  • 105.
    Pommer, Linda
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Ekologi och geovetenskap.
    Oxidation of terpenes in indoor environments: A study of influencing factors2003Doktorsavhandling, sammanläggning (Övrigt vetenskapligt)
    Abstract [en]

    In this thesis the oxidation of monoterpenes by O3 and NO2 and factors that influenced the oxidation were studied. In the environment both ozone (O3) and nitrogen dioxide (NO2) are present as oxidising gases, which causes sampling artefacts when using Tenax TA as an adsorbent to sample organic compounds in the air. A scrubber was developed to remove O3 and NO2 prior to the sampling tube, and artefacts during sampling were minimised when using the scrubber. The main organic compounds sampled in this thesis were two monoterpenes, alfa-pinene and delta-3-carene, due to their presence in both indoor and outdoor air. The recovery of the monoterpenes through the scrubber varied between 75-97% at relative humidities of 15-75%.

    The reactions of alfa-pinene and delta-3-carene with O 3, NO2 and nitric oxide (NO) at different relative humidities (RHs) and reaction times were studied in a dark reaction chamber. The experiments were planned and performed according to an experimental design were the factors influencing the reaction (O3, NO2, NO, RH and reaction times) were varied between high and low levels. In the experiments up to 13% of the monoterpenes reacted when O3, NO2, and reaction time were at high levels, and NO, and RH were at low levels. In the evaluation eight and seven factors (including both single and interaction factors) were found to influence the amount of alfa-pinene and delta-3-carene reacted, respectively. The three most influencing factors for both of the monoterpenes were the O 3 level, the reaction time, and the RH. Increased O3 level and reaction time increased the amount of monoterpene reacted, and increased RH decreased the amount reacted.

    A theoretical model of the reactions occurring in the reaction chamber was created. The amount of monoterpene reacted at different initial settings of O3, NO2, and NO were calculated, as well as the influence of different reaction pathways, and the concentrations of O3 and NO2, and NO at specific reaction times. The results of the theoretical model were that the reactivity of the gas mixture towards alfa-pinene and delta-3-carene was underestimated. But, the calculated concentrations of O3, NO2, and NO in the theoretical model were found to correspond to a high degree with experimental results performed under similar conditions. The possible associations between organic compounds in indoor air, building variables and the presence of sick building syndrome were studied using principal component analysis. The most complex model was able to separate 71% of the “sick” buildings from the “healthy” buildings. The most important variables that separated the “sick” buildings from the “healthy” buildings were a more frequent occurrence or a higher concentration of compounds with shorter retention times in the “sick” buildings.

    The outcome of this thesis could be summarised as follows;

    -

    -

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    -

  • 106. Reinikainen, Marko
    et al.
    Lövgren, Johan
    Umeå universitet, Teknisk-naturvetenskaplig fakultet, Ekologi och geovetenskap.
    Persson, Lennart
    Associations between the microbial community and metazoan grazers as affected by allochtonous resources in aquatic microcosmsManuskript (Övrigt vetenskapligt)
  • 107.
    Rünell, Marlene
    Umeå universitet, Teknisk-naturvetenskaplig fakultet, Ekologi och geovetenskap.
    Transport av 2-veckorskalven: är gällande djurskyddslagstiftning rimlig ur kalhälsosynpunkt?2008Självständigt arbete på avancerad nivå (magisterexamen), 20 poäng / 30 hpStudentuppsats (Examensarbete)
  • 108.
    Samuelsson, Kristina
    Umeå universitet, Teknisk-naturvetenskaplig fakultet, Ekologi och geovetenskap.
    Mechanisms structuring the pelagic microbial food web: Importance of resource and predation2003Doktorsavhandling, sammanläggning (Övrigt vetenskapligt)
    Abstract [en]

    Temporal and spatial variations of pelagic microorganisms in the northern Baltic Sea were studied, as well as factors influencing their abundance and growth rates. Three main questions were asked 1) How does increased productivity influence the structure of the microbial food web? 2) Does predation limitation vary between trophic levels? 3) What is the relative importance of resource and predation limitation at different trophic levels?

    A field study in the northern Baltic Sea showed that dominating protozoa, flagellates and ciliates, increased with increasing primary productivity from north to south. Furthermore, relatively small protozoan cells dominated in the low productive north, while larger cells became more dominant in the south. The relationship between plankton size structure and productivity was further studied in an experimental system. In agreement with present theories regarding nutrient status of pelagic food webs, increased productivity caused a lengthening of the food chain as well as a change in plankton size structure. While microplankton dominated in nutrient rich treatments pico- and nanoplankton dominated during nutrient poor treament. The flagellate community was dominated by a potentially mixotroph, Chrysochromulina sp., at low nutrient concentrations. To our knowledge this is the first experimental study showing that Chrysochromulina sp. in resemblance with other mixotrophs is favoured by nutrient poor conditions compared to strict autotrophs and heterotrophs.

    During a stratified summer period autotrophic microorganisms in the northern Baltic Sea did not respond to removal of potential predators, indicating that they were primarily limited by inorganic nutrients. An exception was small eucaryotic picoplankton that showed a large response to predator removal. Among the heterotrophic microorganisms direct effect of predation seemed to increase from ciliates, heterotrophic bacteria, small heterotrophic flagellates, medium flagellates to large flagellates. No quick indirect effect was observed, but after four days trophic cascades were detected.

    The relative importance of resource and predation limitation was studied among heterotrophic bacteria, flagellates and ciliates in the northern Baltic Sea. For all these groups, resource limitation seemed to prevail during the summer period. The results also indicated that the relative importance of predation increased with the productivity of the system. To our knowledge there are no earlier measurements on the relative importance of resource and predation limitation for micoorganisms in the pelagic environment.

  • 109.
    Samuelsson, Kristina
    et al.
    Umeå universitet, Teknisk-naturvetenskaplig fakultet, Ekologi och geovetenskap.
    Andersson, Agneta
    Factors structuring the protozoan community along a brackish water productivity gradientManuskript (Övrigt vetenskapligt)
  • 110.
    Samuelsson, Kristina
    et al.
    Umeå universitet, Teknisk-naturvetenskaplig fakultet, Ekologi och geovetenskap.
    Andersson, Agneta
    Predation limitation of the pelagic microbial food web in an oligotrophic aquatic system2003Ingår i: Aquatic Microbial Ecology, ISSN 0948-3055, Vol. 30, nr 3, s. 239-250Artikel i tidskrift (Refereegranskat)
  • 111.
    Samuelsson, Kristina
    et al.
    Umeå universitet, Teknisk-naturvetenskaplig fakultet, Ekologi och geovetenskap.
    Johnny, Berglund
    Haecky, Pia
    Andersson, Agneta
    Structural changes in an aquatic microbial food web caused by inorganic nutrient addition2002Ingår i: Aquatic Microbial Ecology, ISSN 0948-3055, Vol. 29, nr 1, s. 29-38Artikel i tidskrift (Refereegranskat)
  • 112.
    Sjöberg, Kjell
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Ekologi och geovetenskap.
    Temporal relationships between fish-eating birds and their prey in a north Swedish river1987Doktorsavhandling, sammanläggning (Övrigt vetenskapligt)
    Abstract [en]

    The seasonal and diel feeding habits of the goosander, Mergus merganser, the red-breasted merganser, M. serrator, gulls (Larus canus, L. argentatus and L. fuscusj and terns, Sterna hirundo/paradisaea were studied at 64V05'N. Birds' activity patterns were influenced by the nocturnal spawning of the river lamprey (Lampetra fluviatilis). Food selection and food consumption by hand-raised mergansers together with aquarium studies of the diel activity patterns of their most important prey supplemented the field data. River lamprey dominated the diet of the goosander by weight and the sculpin Cottus gobio by number. The fish consumption of the goosanders was found to be about 12% of the available river lamprey biomass and about 17% of the sculpin biomass during the breeding season.

    In experimental situations the river lamprey was a low- pritority species compared with salmon , Salmo salar, brown trout, 53. trutta, and minnow, Phoxinus phoxinus, when presented to satiated birds of both Mergus species. When hungry, however, the birds caught the available prey irrespective of species, but they selected larger prey when two size classes were present. Experimental results were compared with field data on availability, consumption and the escape behaviour of the various fish species.

    The rivers emptying in the Bothnian Bay are regarded as important feeding areas for birds breeding along the coast. In early spring they get access to abundant and reliable food resources, e.g the river lamprey. Later on the three-spined stickleback, Gasterosteus aculeatus, supply both Mergus species with food in the river and also along the coast. From the middle of June potential food supply available to birds decreases in the rivers and becomes more abundant in the coastal area.

  • 113. Sobek, Sebastian
    et al.
    Algesten, Grete
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Ekologi och geovetenskap.
    Bergström, Ann-Kristin
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för ekologi, miljö och geovetenskap.
    Jansson, Mats
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för ekologi, miljö och geovetenskap.
    Tranvik, Lars J
    The catchment and climate regulation of pCO2 in boreal lakes2003Ingår i: Global Change Biology, Vol. 9, nr 4, s. 630-641Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    The regulation of surface water pCO2 was studied in a set of 33 unproductive boreal lakes of different humic content, situated along a latitudinal gradient (57°N to 64°N) in Sweden. The lakes were sampled four times during one year, and analyzed on a wide variety of water chemistry parameters. With only one exception, all lakes were supersaturated with CO2 with respect to the atmosphere at all sampling occasions. pCO2 was closely related to the DOC concentration in lakes, which in turn was mainly regulated by catchment characteristics. This pattern was similar along the latitudinal gradient and at different seasons of the year, indicating that it is valid for a variety of climatic conditions within the boreal forest zone. We suggest that landscape characteristics determine the accumulation and subsequent supply of allochthonous organic matter from boreal catchments to lakes, which in turn results in boreal lakes becoming net sources of atmospheric CO2.

  • 114.
    Strengbom, Joachim
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Ekologi och geovetenskap.
    Nitrogen, parasites and plants: key interactions in boreal forest ecosystems2002Doktorsavhandling, sammanläggning (Övrigt vetenskapligt)
    Abstract [en]

    In the work described in this thesis I studied how increases in nitrogen (N) inputs may affect plant community structure in boreal forest understorey vegetation. These phenomena were investigated in N fertilization experiments and along a national N deposition gradient. After five years of N additions, large changes in understorey vegetation composition were observed in the fertilization study. In plots that received 50 kg N ha'1 year"1 (N2), the abundance of the dominant species, Vaccinium myrtillus, decreased on average by 32 %. No decrease was observed in control plots during the same period. In contrast, the grass Deschampsia flexuosa responded positively to increased N input, being on average more than five times as abundant in the N2 treatments as in controls.

    Also an increase was seen in the incidence of disease caused by the parasitic fungus Valdensia heterodoxa on leaves of V. myrtillus following N additions. The parasite was on average nearly twice as abundant in N2 plots than in control plots. This could be explained by increased N concentrations in host plant tissue. Disease incidence also increased following experimental additions of glutamine to leaf surfaces of V. myrtillus, suggesting a causal connection between plant N concentration and performance of the fungus. The parasite also played a key role in the observed changes in understorey species composition. D. flexuosa was more abundant in patches in which V. myrtillus was severely affected by V heterodoxa. This suggests that V heterodoxa mediates the increased abundance of D. flexuosa following increased N additions. The fungus mediates changes in the composition of understorey vegetation mainly by increasing light availability via premature leaf loss of V. myrtillus.

    The incidence of disease due to the parasite was on average higher in large than in smaller N-treated plots, indicating that the response to N fertilization is spatially scale dependent. This shows that using small plot sizes in experiments that simulate changed environmental conditions may be problematic, as important interactions may be underestimated.

    Comparison of the occurrence of understorey species between regions with different rates of N deposition revealed that the occurrence of the two dwarf shrubs V. myrtillus and V. vitis- idaea was lower in regions with high N deposition compared to regions with low deposition. The opposite pattern was found for V heterodoxa. This is consistent with expectations from N fertilization experiments. For D. flexuosa no differences in occurrence were found between the different regions investigated.

    The effects on vegetation and mycorrhizal fungi observed following N additions were also found to be long lasting. Nine years after termination of the fertilization, no signs of recovery were detected, and nearly 50 years after termination characteristic signs of N fertilization were found among bryophytes and mycorrhizal fungi. This suggests that the time needed for re-establishment of the original biota following N-induced changes may be substantial.

  • 115.
    Strid, Åke
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Ekologi och geovetenskap.
    Wood-inhabiting fungi of alder forests in north-central Scandinavia: 1, Aphyllophorales (Basidiomycetes). Taxonomy, ecology and distribution1975Doktorsavhandling, monografi (Övrigt vetenskapligt)
    Abstract [en]

    Wood-inhabiting fungi were collected on different trees in 99 loca-' lities of alder woods, dominated by Alnus incana or occasionally A. glutinosa, in N-C Sweden and C Norway. Most of the localities are situated near the east coast of Sweden where the prevailing land elevation creates conditions suitable for colonization by alder. The remaining localities are mainly found in the inland parts of Sweden and Norway, along streams, in ravines etc. The investigated localities are briefly described as to their general vegetation, and a regional survey of the alder forests is given.

    The number of collections of Aphyllophorales amounts to approxi­mately 5,000, comprising 286 species. The following new combinations are proposed: Hypoohnicium polonense (Bres.) Strid, H. pruinosum (Bres.) Strid, Phlebia lindtneri (Pil.) Parm. and Sistotrema hete- roncmum (John Erikss.) Strid. Seven species are collected as new to Scandinavia, viz., Botryobasidium aure urn3 Ceratobasidium stridiit Hyphoderma orphanellum, Hyphodontiella multiseptata, Hypoohnicium pruinosum> Phlebia lindtneri and Tubuliorinis effugiens, and approxi­mately 85 additional species are reported for the first time from the investigation area. Six specimens of Cortioiaoeae have remained undetermined but are included in the species list. Most of them represent species new to science, but they are not, for different reasons, described as new species. Preliminary, one of them is re­ferred to Ceratobasidium, one to Hyphoderma and two to Sistotrema.

    All species are presented in a list with annotations on their aut- ecology, distribution in Scandinavia and, when needed, taxonomy. The records of species collected more than once are mapped on 196 maps.

    The ecology of wood-inhabiting Aphyllophorales in alder forests is discussed, including habitat conditions (decay, moisture, tempera­ture, soil conditions), distribution of fungi on different host trees, succession of fungi and some regional-ecological traits.

    The distribution of fungi is summarized by a grouping of represen­tative species into flora elements which, in turn, are compared to those that have been proposed for vascular plants.

  • 116.
    Svanbäck, Richard
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Ekologi och geovetenskap.
    Ecology and Evolution of Adaptive Morphological Variation in Fish Populations2004Doktorsavhandling, sammanläggning (Övrigt vetenskapligt)
    Abstract [en]

    The work in this thesis deals with the ecology and evolution of adaptive individual variation. Ecologists have long used niche theory to describe the ecology of a species as a whole, treating conspecific individuals as ecological equivalent. During recent years, research about individual variation in diet and morphology has gained interest in adaptive radiations and ecological speciation. Such variation among individual niche use may have important conservation implications as well as ecological and evolutionary implications. However, up to date we know very little about the extension of this phenomenon in natural populations and the mechanisms behind it.

    The results in this thesis show that the extension of individual diet specialization is widely spread throughout the animal kingdom. The variation in diet is mainly correlated to morphological variation but not always. Furthermore, this variation in diet and morphology among individuals could be both genetically determined and environmentally induced and it mainly comes from trade-offs in foraging efficiency between different prey types.

    The results from a number of studies of perch also show that individual perch differ in morphology and diet depending on habitat, where littoral perch has a deeper body compared to pelagic perch. This difference in morphology corresponds to functional expectations and is related to foraging efficiency trade-offs between foraging in the littoral and pelagic zone of a lake. The variation in morphology in perch is mainly due to phenotypic plasticity but there are also small genetic differences between the littoral and pelagic perch. Two separate studies show that both predation and competition may be important mechanism for the variation in morphology and diet in perch.

    In conclusion, the results in this thesis show that individual variation in diet and habitat choice is a common phenomenon with lots of ecological and evolutionary implications. However, there are many mechanisms involved in this phenomenon on which we are just about to start learning more about, and only further research in this area will give us the full insight.

  • 117.
    Svanbäck, Richard
    et al.
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Ekologi och geovetenskap.
    Eklöv, Peter
    Effects of habitat and food resources on morphology and ontogenetic growth trajectories in perch2002Ingår i: Oecologia, Vol. 131, s. 61-70Artikel i tidskrift (Refereegranskat)
  • 118.
    Svanbäck, Richard
    et al.
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Ekologi och geovetenskap.
    Eklöv, Peter
    Genetic variation and phenotypic plasticity: Causes of morphological and dietary variation in Eurasian perch2006Ingår i: Evolutionary Ecology Research, ISSN 1522-0613, E-ISSN 1937-3791, Vol. 8, nr 1, s. 37-49Artikel i tidskrift (Refereegranskat)
  • 119.
    Svanbäck, Richard
    et al.
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Ekologi och geovetenskap.
    Eklöv, Peter
    Morphology dependent foraging efficiency in perch: a trade-off for ecological specialization?2003Ingår i: Oikos, Vol. 102, s. 273-284Artikel i tidskrift (Refereegranskat)
  • 120. Sörensen, Rasmus
    et al.
    Zinko, Ursula
    Umeå universitet, Teknisk-naturvetenskaplig fakultet, Ekologi och geovetenskap.
    Seibert, Jan
    On the calculation of the topographic wetness index: evaluation of different methods based on field observations.2006Ingår i: Hydrology and Earth System Sciences, ISSN 1027-5606, E-ISSN 1607-7938, Vol. 10, nr 1, s. 101-112Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    The topographic wetness index (TWI, ln(a/tan beta)), which combines local upslope contributing area and slope, is commonly used to quantify topographic control on hydrological processes. Methods of computing this index differ primarily in the way the upslope contributing area is calculated. In this study we compared a number of calculation methods for TWI and evaluated them in terms of their correlation with the following measured variables: vascular plant species richness, soil pH, groundwater level, soil moisture, and a constructed wetness degree. The TWI was calculated by varying six parameters affecting the distribution of accumulated area among downslope cells and by varying the way the slope was calculated. All possible combinations of these parameters were calculated for two separate boreal forest sites in northern Sweden. We did not find a calculation method that performed best for all measured variables; rather the best methods seemed to be variable and site specific. However, we were able to identify some general characteristics of the best methods for different groups of measured variables. The results provide guiding principles for choosing the best method for estimating species richness, soil pH, groundwater level, and soil moisture by the TWI derived from digital elevation models.

  • 121.
    Tatarenkov, A.
    et al.
    Department of Marine Ecology, Tjärnö Marine Biological Laboratory, Göteborg University.
    Bergström, Lena
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Ekologi och geovetenskap.
    Jönsson, Rita B.
    Department of Biology and Environmental Sciences, Kalmar University.
    Serrão, Ester A.
    CCMAR-Centre of Marine Sciences, University of Algarve, Gambelas, Portugal.
    Kautsky, Lena
    Department of Botany, Stockholm University.
    Johannesson, Kerstin
    Department of Marine Ecology, Tjärnö Marine Biological Laboratory, Göteborg University.
    Intriguing asexual life in marginal populations of the brown seaweed Fucus vesiculosus2005Ingår i: Molecular Ecology, ISSN 0962-1083, E-ISSN 1365-294X, Vol. 14, nr 2, s. 647-651Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Reproduction of attached large brown algae is known to occur only by sexual zygotes. Using microsatellites we show evolution of asexual reproduction in the bladder wrack promoting population persistence in the brackish water Baltic Sea (< 6 psu). Here a dwarf morph ofFucus vesiculosus is dominated by a single clone but clonal reproduction is also present in the common form of the species. We describe a possible mechanism for vegetative reproduction of attached algae, and conclude that clonality plays an important role in persistence and dispersal of these marginal populations, in which sexual reproduction is impaired by low salinity.

  • 122. Turchin, Peter
    et al.
    Oksanen, Lauri
    Ekerholm, Per
    Umeå universitet, Teknisk-naturvetenskaplig fakultet, Ekologi och geovetenskap.
    Oksanen, Tarja
    Henttonen, Heikki
    Are lemmings prey or predators?2000Ingår i: Nature, ISSN 0028-0836, Vol. 405, s. 562-565Artikel i tidskrift (Refereegranskat)
  • 123. Wastensson, Leif
    et al.
    Wiberg, Ulf
    Umeå universitet, Samhällsvetenskapliga fakulteten, Kulturgeografiska institutionen.
    Bylund, Erik
    Umeå universitet, Samhällsvetenskapliga fakulteten, Kulturgeografiska institutionen.
    Westin, Kerstin
    Umeå universitet, Samhällsvetenskapliga fakulteten, Kulturgeografiska institutionen.
    Jansson, Bruno
    Umeå universitet, Samhällsvetenskapliga fakulteten, Kulturgeografiska institutionen.
    Lassila, Mauno
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Ekologi och geovetenskap.
    Müller, Dieter K.
    Umeå universitet, Samhällsvetenskapliga fakulteten, Kulturgeografiska institutionen.
    Övre Norrland: Förslag om en regional atlas2004Rapport (Övrigt vetenskapligt)
  • 124.
    Zhang, Yixin
    Umeå universitet, Teknisk-naturvetenskaplig fakultet, Ekologi och geovetenskap.
    Balancing food availability and hydrodynamic constraint: phenotypic plasticity and growth in Simulium noelleri blackfly larvae.2006Ingår i: Oecologia, ISSN 0029-8549, E-ISSN 1432-1939, Vol. 147, nr 1, s. 39-46Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Organisms through phenotypic plasticity can cope with multiple changed environmental conditions. Theory predicts that animals in streams and rivers should be able to balance demands of the needs to obtain food efficiently and to adjust response to hydrodynamic variability. This study examined effects of variations in food availability and current velocity on the feeding structure and growth rate of Simulium noelleri blackfly larvae. The larvae developed larger labral fans and more rays under slow current and low food regimes than in fast current and high food conditions. In both fast and slow current regimes, growth rates were higher and development periods to the final-instar stage were shorter in high food treatments. The estimated flux rates of food particles through labral fans under high food treatments for both fast and slow current regimes were higher than those under low food treatments. Although both food and current velocity appeared to have selected for flexibility of feeding structure and growth rate, food availability was a more important factor for phenotypic and developmental plasticity than current velocity. The results indicate a strong link between environmental changes in food availability and current velocity, phenotypic plasticity, and growth rate of S. noelleri. This study suggests that plasticity of ecomorphs with macroevolutionary significance may play a role in the early evolutionary stages of blackfly larvae.

  • 125.
    Zinko, Ursula
    Umeå universitet, Teknisk-naturvetenskaplig fakultet, Ekologi och geovetenskap.
    Plants go with the flow: predicting spatial distribution of plant species in the boreal forest2004Doktorsavhandling, sammanläggning (Övrigt vetenskapligt)
    Abstract [sv]

    Syftet med avhandlingen är att dels studera om ett topografiskt fuktighetsindex skulle kunna vara användbart för att förutsäga fördelningen av kärlväxters artrikedom i boreal skog, dels att studera om den rumsliga fördelningen av artrikedom hos kärlväxter, blad- och levermossor samt lavar sammanfaller.

    Ett fuktighetsindex, ln(a/tanβ), som bara är baserat på topografi användes för att beräkna ett indexvärde för varje 20 x 20 m grid i två 25 km2 stora boreala skogslandskap (med i medeltal olika mark-pH) i norra Sverige. Det är känt att mark-pH påverkas av grundvatten och att pH i sin tur påverkar artrikedom hos kärlväxter i andra biom. Därför studerades även sambanden mellan kärlväxters artrikedom, mark pH och TWI.

    Resultaten visade att större delen av det studerade boreala landskapet var relativt torrt och artfattigt, medan mindre utspridda områden med höga TWI-värden var artrika på kärlväxter och här växte även arter som återfanns i de torra delarna av skogen. Sambandet mellan artrikedom hos kärlväxter och TWI var positivt i båda landskapen, men påverkades av de olika nivåerna på mark-pH. TWI förklarade 30 % av variationen i artrikedom i området med lägre mark-pH respektive 50 % i området med högre mark-pH. Andelen kärlväxter som klassificeras som icke vanliga i respektive region ökade också med TWI. Med andra beräkningsmetoder för TWI visade det sig att styrkan på korrelationerna mellan TWI och olika uppmätta variabler (artrikedom hos kärlväxter, mark-pH, grundvattennivå och markfuktighet) varierade mycket. Sambandet mellan artrikedom hos kärlväxter och TWI kunde förbättras ytterligare med vissa beräkningsmetoder.

    Då korrelationer i artrikedom studerades användes ett dataset från boreal skog i norra Sverige. Resultaten visade på starka, positiva korrelationer mellan kärlväxter, blad- och levermossor, men inga korrelationer mellan någon av dessa grupper och lavar. Detta kunde förklaras med att artrikedom hos de tre korrelerande organismgrupperna ökar med ökad fuktighet, medan artrikedom hos lavar inte är kopplat till fukt.

    Huvudslutsatsen i avhandlingen är att TWI, som endast är baserad på topograpfiskt data, skulle kunna bli ett värdefullt redskap i naturvårdsplanering för att identifiera särskilt intressanta skogsområden innan man gör fältinventeringar. Eftersom studien visar att kärlväxter kan användas som en indikator grupp för artrikedom hos blad- och levermossor indikerar höga TWI-värden områden med hög artrikedom även vad gäller dessa taxa.

  • 126.
    Zinko, Ursula
    et al.
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Ekologi och geovetenskap.
    Dynesius, Mats
    Nilsson, Christer
    Seibert, Jan
    The importance of soil moisture and pH for the spatial variation of plant species numbers in boreal forests.Manuskript (preprint) (Övrigt vetenskapligt)
  • 127.
    Zinko, Ursula
    et al.
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Ekologi och geovetenskap.
    Seibert, Jan
    Dynesius, Mats
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för ekologi, miljö och geovetenskap.
    Nilsson, Christer
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för ekologi, miljö och geovetenskap.
    Plant species number predicted by a topography based groundwater-flow index2005Ingår i: Ecosystems (New York. Print), ISSN 1432-9840, E-ISSN 1435-0629, Vol. 8, nr 4, s. 430-441Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    The lack of a clear understanding of the factors governing the often-great variation of species numbers over entire landscapes confounds attempts to manage biodiversity. We hypothesized that in a topographically variable boreal forest landscape the availability of shallow groundwater is a major determinant of plant species numbers. We then developed a topographically derived hydrologic index based on multidirectional flow algorithms to account for the variation in availability of such groundwater in the landscape. We found a positive correlation between species numbers of vascular plants in plots ranging from 0.01 to 200 m2 and the hydrologic index. Generally, the landscape was relatively dry and species-poor, but interspersed patches with shallow groundwater had high species numbers and high proportions of regionally uncommon plant species. The index explained 30% of the variation in vascular plant number and correlated quite well (rs = 0.50) with groundwater level, but not as well with a community H+concentration value (instead of community pH, rs = −0.31), based on species composition. In addition, we found a very strong correlation between species number and the community H+ concentration value (rs−0.84). The hydrologic index is a useful tool for the identification of spatial of species number patterns across entire landscapes. This is an important step in identifying the areas most in need of protection or restoration, designing survey techniques, and understanding the fundamental processes that control the spatial distribution of species.

  • 128. Ågren, Jon
    et al.
    Olsson, Katarina
    Umeå universitet, Teknisk-naturvetenskaplig fakultet, Ekologi och geovetenskap.
    Genetic architecture of phenology, flower morphology and inflorescence size in two populations of the perennial herb Lythrum salicaria.Manuskript (Övrigt vetenskapligt)
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