Sökning: "ekologisk botanik"

Visar resultat 6 - 10 av 66 avhandlingar innehållade orden ekologisk botanik.

1. 6. Wood-inhabiting fungi of alder forests in north-central Scandinavia : 1, Aphyllophorales (Basidiomycetes). Taxonomy, ecology and distribution

   Författare :Åke Strid; Umeå universitet; []
   Nyckelord :NATURVETENSKAP; NATURAL SCIENCES; Basidiesvampar; ekologisk botanik; Ecological Botany;

   Sammanfattning : 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. LÄS MER

3. 7. The natural holocene vegetation development and the introduction of agriculture in northern Norrland, Sweden : studies of soil, peat and especially varved lake sediments

   Författare :Ulf Segerström; Umeå universitet; []
   Nyckelord :NATURVETENSKAP; NATURAL SCIENCES; Jordbruk-- Sverige -- Norrbotten; Växtekologi-- Sverige -- Norrbotten; Lule älvdal;

   Sammanfattning : The Holocene vegetation history of northern Norrland was studied by pollen analysis of sediement, peat and soil samples, with the aim to improve our knowledge about vegetation development in northern Norrland, and also about the history of man and the introduction of agriculture in the area. Earlier made pollen analyses from the four northernmost provinces were summarized and a series of new analyses from northern Norrland added. LÄS MER

4. 8. Systemic fungal diseases in natural plant populations

   Författare :Anders Wennström; Lars Ericson; Peter G. Ayres; Umeå universitet; []
   Nyckelord :NATURVETENSKAP; NATURAL SCIENCES; Systemic diseases; rust; smut; Puccinia minussensis; Lactuca sibirica; Puccinia pulsatillae; Pulsatilla pratensis; lateral growth; abiotic factors; disease transmission; Svampsjukdomar hos växter;

   Sammanfattning : The purpose of this thesis was to study interactions between systemic fungal diseases and perennial plants. Using the systemic rust Puccinia minussensis on the host plant Lactuca sibirica, and the rust Puccinia pulsatillae on the host plant Pulsatilla pratensis, this thesis focused on: (i) the effects of systemic diseases on their hosts (ii) host and pathogen responses to abiotic factors, (iii) the importance of life history strategies for understanding host-pathogen interactions, and (iv) the evolutionary consequences of living in close associations. LÄS MER

5. 9. Herbivory and plant community structure in a subarctic altitudinal gradient

   Författare :Jon Moen; Nancy Huntly; Umeå universitet; []
   Nyckelord :NATURVETENSKAP; NATURAL SCIENCES; NATURVETENSKAP; NATURAL SCIENCES; arctic and alpine vegetation; competition; exclosures; lemmings; plant defences; plant-plant interactions; Ranunculus glacialis; snow-bed; structuring factors; tall herb meadow; vertebrate grazing; voles;

   Sammanfattning : The object of this thesis was to study plant community structure, especially in relation to vertebrate herbivory, in an altitudinal gradient in the Fennoscandian mountain chain.A sowing experiment in a high alpine Ranunculus glacialis population showed that seeds germinated better in cleared microsites than under established individuals. LÄS MER

7. 10. Life History and Tolerance and Resistance against Herbivores in Natural Populations of Arabidopsis thaliana

   Författare :Reiko Akiyama; Jon Ågren; Arjen Biere; Uppsala universitet; []
   Nyckelord :NATURVETENSKAP; NATURAL SCIENCES; NATURVETENSKAP; NATURAL SCIENCES; NATURVETENSKAP; NATURAL SCIENCES; Arabidopsis thaliana; life history evolution; flowering time; germination; phenology; plant-herbivore interactions; natural selection; tolerance to leaf damage; resistance to herbivory; Plutella xylostella; Mamestra brassicae; Biology with specialization in Ecological Botany; Biologi med inriktning mot ekologisk botanik;

   Sammanfattning : In this thesis, I combined observational studies with field and greenhouse experiments to examine selection on life history traits and variation in tolerance and resistance against herbivores in natural populations of the annual herb Arabidopsis thaliana in its native range. I investigated (1) phenotypic selection on flowering time and plant size, (2) the effects of timing of germination on plant fitness, (3) the effect of leaf damage on seed production, and (4) correlations between resistance against a specialist and a generalist insect herbivore. LÄS MER