Sökning: "local abundance"

Visar resultat 1 - 5 av 127 avhandlingar innehållade orden local abundance.

1. 1. Dynamics of ecological communities in variable environments : local and spatial processes

   Författare :Linda Kaneryd; Bo Ebenman; Peter Münger; Michael S. Fowler; Linköpings universitet; []
   Nyckelord :;

   Sammanfattning : The ecosystems of the world are currently facing a variety of anthropogenic perturbations, such as climate change, fragmentation and destruction of habitat, overexploitation of natural resources and invasions of alien species. How the ecosystems will be affected is not only dependent on the direct effects of the perturbations on individual species but also on the trophic structure and interaction patterns of the ecological community. LÄS MER

3. 2. Palaeoenvironmental changes in the northern boreal zone of Finland: local versus regional drivers

   Författare :Shyhrete Shala; Karin H. Helmens; Christian Bigler; Stockholms universitet; []
   Nyckelord :NATURVETENSKAP; NATURAL SCIENCES; Palaeolimnology; Palaeoecology; Biological assemblages; Sediment geochemistry; Regional drivers; Local drivers; Quantitative temperature reconstructions; Transfer-functions; Holocene; MIS 5d-c; Northern boreal zone; NE Finland; kvartärgeologi; Quaternary Geology;

   Sammanfattning : Multiple proxies derived from the Lake Loitsana sediment sequence (NE Finland) are employed to determine the timing of deglaciation, characterise an early Holocene proglacial lake stage and reconstruct Holocene lake development. Local-scale processes causing shifts in biological assemblages are identified and the most likely Holocene mean July air temperature (Tjul) development is assessed. LÄS MER

4. 3. Metapopulation and metacommunity processes, dispersal strategies and life-history trade-offs in epiphytes

   Författare :Swantje Löbel; Håkan Rydin; Tord Snäll; Lars E. Ericson; Uppsala universitet; []
   Nyckelord :NATURVETENSKAP; NATURAL SCIENCES; asexual; biodiversity; bryophytes; dispersal limitation; establishment; evolution of reproductive traits; germination; growth; habitat fragmentation; landscape dynamics; local processes; patch-tracking; pH; reproduction; species richness; species interactions; Other biology; Övrig biologi; Ecological Botany; Ekologisk botanik;

   Sammanfattning : The aim of this thesis was to increase knowledge about metapopulation and metacommunity processes in patchy, dynamic landscapes, using epiphytic bryophytes as a model system. Host trees and deciduous forest stands in the coniferous landscape are patchy, temporal and undergo changes in habitat quality during succession. LÄS MER

5. 4. Plant-Animal Interactions and Evolution of Floral Display and Flowering Phenology in Arabidopsis lyrata

   Författare :Saskia Sandring; Jon Ågren; Johan Ehrlén; José Gómez; Uppsala universitet; []
   Nyckelord :Ecology; Arabidopsis lyrata; natural selection; floral display; phenology; flowering time; plant-animal interactions; pollination; herbivory; selection gradients; population differentiation; local adaptation; Ekologi;

   Sammanfattning : In this thesis, I combined comparative and experimental approaches to examine selection on reproductive traits, and population differentiation in the insect-pollinated, outcrossing, perennial herb Arabidopsis lyrata. More specifically, I (1) determined whether selection on flowering phenology and floral display can be attributed to interactions with pollinators and herbivores, (2) examined whether population differentiation in flowering phenology and floral display is correlated with current selection on these traits, and (3) tested for local adaptation from contrasting environments in Europe. LÄS MER

7. 5. Species interactions and community structure

   Författare :Peter Frodin; Technology and Social Change (WTS) Centre for Work; []
   Nyckelord :NATURVETENSKAP; NATURAL SCIENCES; Ecology; Ekologi; spatial structure; local stability; enrichment; species interactions; Community structure; population dynamics;

   Sammanfattning : In this theses I have focused on how the mechanisms of species interactions affect community structure. It is well known that certain species may have a particularly strong influence on the structure of a community. What is not fully understood is how to characterize these species that have such a strong impact on community structure. LÄS MER