Sökning: "seed predation"

Visar resultat 6 - 10 av 24 avhandlingar innehållade orden seed predation.

1. 6. Pests and pest controlling organisms across tropical agroecological landscapes in relation to forest and tree-cover

   Författare :Debissa Lemessa; Kristoffer Hylander; Peter Hambäck; Martin Entling; Stockholms universitet; []
   Nyckelord :NATURVETENSKAP; NATURAL SCIENCES; activity abundance; crop raiding; exclosure experiment; homegarden; leaf damage; predation; spatial scales; structural complexity; Plant Ecology; växtekologi;

   Sammanfattning : A major challenge in agroecosystems is how to manage the systems so that it reduces crop pests and enhances natural pest control. This thesis investigates patterns of crop pests and top-down effects of birds and arthropod predators in relation to land-use composition across spatial scales. LÄS MER

3. 7. Linking plant population dynamics to the local environment and forest succession

   Författare :Johan Petter Dahlgren; Johan Ehrlén; Ove Eriksson; Mark Rees; Stockholms universitet; []
   Nyckelord :NATURVETENSKAP; NATURAL SCIENCES; Actaea spicata; Forest herbs; Forest succession; Integral projection model; Plant demography; Plant phenology; Population dynamics; Pre-dispersal seed predation; Seed mass; Soil potassium; Specific leaf area; Terrestrial ecology; Terrestisk ekologi; Plant Ecology; växtekologi;

   Sammanfattning : Linking environmental variation to population dynamics is necessary to understand and predict how the environment influences species abundances and distributions. I used demographic, environmental and trait data of forest herbs to study effects of spatial variation in environmental factors on populations as well as environmental change in terms of effects of forest succession on field layer plants. LÄS MER

4. 8. Pollinators, Enemies, Drought, and the Evolution of Reproductive Traits in Primula farinosa

   Författare :Per Toräng; Jon Ågren; Johan Ehrlén; Rebecca Irwin; Uppsala universitet; []
   Nyckelord :NATURVETENSKAP; NATURAL SCIENCES; NATURVETENSKAP; NATURAL SCIENCES; Ecology; Alternative reproductive strategies; climate change; facilitation; floral display; flowering phenology; frequency-dependent selection; genetic diversity; life-history strategies; local adaptation; pollination; predation; Primula farinosa; reproductive effort; soil disturbance; stochastic growth rate; Ekologi;

   Sammanfattning : In this thesis, I combined comparative and experimental approaches to examine selection on reproductive traits and population differentiation in the insect-pollinated, self-incompatible, perennial herb Primula farinosa. More specifically, I (1) determined whether the effects of floral display and interactions with pollinators and seed predators, and plant reproductive success were frequency-dependent and affected by surrounding vegetation context, (2) examined the consequences of intermittent drought years on population dynamics using numerical simulations based on demographic data collected over seven years, (3) analyzed among-population differentiation in flowering phenology and reproductive allocation, and its relationship to soil-depth at the site of origin. LÄS MER

5. 9. Small remnant habitats : Important structures in fragmented landscapes

   Författare :Jessica Lindgren; Sara Cousins; Regina Lindborg; Adam Kimberley; Ove Eriksson; Hans Henrik Bruun; Stockholms universitet; []
   Nyckelord :NATURVETENSKAP; NATURAL SCIENCES; LANTBRUKSVETENSKAPER; AGRICULTURAL SCIENCES; NATURVETENSKAP; NATURAL SCIENCES; Alpha-diversity; Beta-diversity; Biological pest control; Canopy cover; Connectivity; Ecosystem function; Fleshy fruits; Forest edge; Forest management; Forest specialist species; Fragmentation; Functional diversity; Gamma-diversity; Grassland specialist species; Green infrastructure; Habitat amount hypothesis; Island biogeography; Midfield islets; Plant diversity; Plant-pollinator interaction; Pollination; Remnant habitat; Seed predation; Small habitats; Species richness; Structural heterogeneity; Physical Geography; naturgeografi;

   Sammanfattning : The world-wide intensification of agriculture has led to a decline in species richness due to land use change, isolation, and fragmentation of natural and semi-natural habitats in agricultural and forestry landscapes. As a consequence, there is a current landscape management focus on the importance of green infrastructure to mitigate biodiversity decline and preserve ecosystem functions e. LÄS MER

7. 10. Reproductive allocation and costs of reproduction in subarctic herbs : A resource-based perspective

   Författare :Åsa M. Hemborg; Uppsala universitet; []
   Nyckelord :NATURVETENSKAP; NATURAL SCIENCES; Ecology; Altitudinal gradient; Plant size; Predispersal seed predation; Reproductive effort; Resourcedynamics; Seasonal variation; Sexual dimorphism; Somatic costs; Unisexual plants; Ekologi; Terrestrial; freshwater and marine ecology; Terrestisk; limnisk och marin ekologi; ekologisk botanik; Ecological Botany;

   Sammanfattning : The influence of internal and external factors on two major plant life history components, i.e., reproductive allocation and costs of reproduction, was examined for nine perennial herbs in subarctic Swedish Lapland. In one study, comparisons were made between Sweden and the French Alps. LÄS MER