Sökning: "increased grazing pressure"
Visar resultat 1 - 5 av 20 avhandlingar innehållade orden increased grazing pressure.
1. Submerged macrophytes in shallow eutrophic lakes - regulating factors and ecosystem effects
Sammanfattning : In this thesis I have studied factors that regulate submerged macrophyte abundance, morphology and distribution in shallow eutrophic lakes, and how submerged macrophytes may affect the ecosystem. Light attenuation through the water column (turbidity and water depth) is probably not the most important factor regulating the distribution of submerged vegetation in macrophyte dominated shallow eutrophic lakes, e. LÄS MER
2. Plant-soil-herbivore interactions in a high Arctic wetland - Feedbacks to the carbon cycle
Sammanfattning : Arctic ecosystems hold massive amounts of the global carbon in their soils and are of great importance for the global terrestrial exchange of greenhouse gases to the atmosphere. The arctic region has in general been acting as a C sink for the past 10000 years, however with climate change the C balance in some areas is shifting towards becoming a C source. LÄS MER
3. Habitat-Forming Seaweeds in a Changing Climate
Sammanfattning : Climate change is an umbrella term encompassing some of the largest and most potent selective pressures currently acting on ecosystems. It can have diverse effects on marine systems; the most powerful of which are changes to salinity through altered patterns of precipitation and evaporation, temperature through increased global temperature, and pH through the dissolution of CO2 into seawater where it ultimately reacts with water to form carbonate (CO32-) and hydrogen ions (2H+). LÄS MER
4. Top-down and bottom-up effects in a Fennoscandian tundra community
Sammanfattning : The objective of this thesis was to investigate the effects of mammalian grazers, such as microtine rodents and reindeer, (top-down effects) and nutrient availability (bottom- up effects) on the plant community of a tundra heath.I conducted a large-scale fertilization experiment and studied the impact of grazers using exclosures. LÄS MER
5. Spring dynamics in shallow lakes: the role of plankton, fish and macrophytes in a changing climate
Sammanfattning : Shallow lakes such as Lake Krankesjön are characterized by their extended littoral zones, usually covered by submersed and emergent vegetation. In paper 1, I investigated the relationship between turbidity and macrophyte growth (Chara spp. LÄS MER