Sökning: "Per-anders Esseen"

Hittade 3 avhandlingar innehållade orden Per-anders Esseen.

  1. 1. Ecology of lichens in boreal coniferous forests with reference to spatial and temporal patterns

    Författare :Per-Anders Esseen; Lars Ericson; Umeå universitet; []
    Nyckelord :NATURVETENSKAP; NATURAL SCIENCES; Lichens; epiphytes; Alectoria; Bryoria; Cladonia; Usnea; Picea abies; Pinus sylvestris; dispersal; litterfall; succession; diversity; spatial patterns;

    Sammanfattning : The thesis deals with the ecology of lichens in two contrasting types of forest, epiphytic lichens in old Picea abies forest of the fi re-refugia type and epigeic as well as epixylic lichens in a successional sequence of fire- susceptible Pinus sylvestris forests. Results in five separate papers form the basis for a discussion of general patterns of dispersal, succession and life strategies in lichens. LÄS MER

  3. 2. Forest edges in boreal landscapes - factors affecting edge influence

    Författare :Ulrika Jansson; Per-Anders Esseen; Mats Nilsson; Timo Kuuluvainen; Umeå universitet; []
    Nyckelord :NATURVETENSKAP; NATURAL SCIENCES; aerial photographs; edge contrast; edge density; edge length; fetch size; forest fragmentation; lichen growth; line intersect sampling; pendulous lichen; photo interpretation; skogskant; flygbild; kantlängd; lav; Terrestrial ecology; Terrestisk ekologi; ekologisk botanik; Ecological Botany;

    Sammanfattning : The boreal forest in Fennoscandia has been subjected to major loss and fragmentation of natural forests due to intensive forestry. This has resulted in that forest edges are now abundant and important landscape features. Edges have documented effects on the structure, function and biodiversity in forests. LÄS MER

  4. 3. Modeling lichen performance in relation to climate : scaling from thalli to landscapes

    Författare :Anna V Jonsson Čabrajić; Kristin Palmqvist; Jon Moen; Per-Anders Esseen; Mikaell Ottosson-Löfvenius; Göran Ågren; Umeå universitet; []
    Nyckelord :NATURVETENSKAP; NATURAL SCIENCES; Lichen; growth; model; micro-climate; hydration; activation; photosynthesis; respiration; Terrestrial ecology; Terrestisk ekologi; ekologisk botanik; Ecological Botany;

    Sammanfattning : Lichens can colonize nearly all terrestrial habitats on earth and are functionally important in many ecosystems. Being poikilohydric, their active growth periods are restricted to periods when the thallus is hydrated from atmospheric water sources, such as rain, fog and high relative humidity. LÄS MER