Sökning: "Defoliation"

Visar resultat 6 - 10 av 14 avhandlingar innehållade ordet Defoliation.

1. 6. Remote Sensing of Forest Decline in the Czech Republic

   Författare :Jonas Ardö; Institutionen för naturgeografi och ekosystemvetenskap; []
   Nyckelord :NATURVETENSKAP; NATURAL SCIENCES; Czech Republic; neural networks; sulphur dioxide; air pollution; Norway spruce; deforestation; forest decline; GIS; spectral characteristics; Remote sensing; Landsat; Ore Mountains; Geology; physical geography; Geologi; fysisk geografi;

   Sammanfattning : This thesis describes the localisation and quantification of deforestation and forest damage in Norway spruce forests in northern Czech Republic using Landsat data. Severe defoliation increases the spectral reflectance in all wavelength bands, especially in the mid infrared region. LÄS MER

3. 7. Interactions between ungulates and forest insects

   Författare :Michelle Nordkvist; Sveriges lantbruksuniversitet; Sveriges lantbruksuniversitet; []
   Nyckelord :NATURVETENSKAP; NATURAL SCIENCES;

   Sammanfattning : In forest ecosystems ungulates and insect herbivores often co-occur and utilise the same host trees. Herbivores that share a host plant can indirectly affect each other through plant induced responses. Such changes may affect plant growth, interactions with other species, and population dynamics. LÄS MER

4. 8. Effects of herbivory on arctic and alpine vegetation

   Författare :Åsa Lindgren; Ove Eriksson; Jon Moen; Anders Angerbjörn; Ingibjörg S Jónsdóttir; Stockholms universitet; []
   Nyckelord :NATURVETENSKAP; NATURAL SCIENCES; herbivory; reindeer; rodents; functional traits; plant species composition; arctic; alpine; tundra; seed limitation; Carex bigelowii; Biology; Biologi; Plant Ecology; växtekologi;

   Sammanfattning : The distribution of plant species and functional traits in alpine and arctic environments are determined by abiotic conditions, but also by biotic interactions. In this thesis, I investigate interactions among plants and herbivory effects on plant community composition and plant functional traits in three different regions: Swedish Lapland, Beringia (USA/Russia) and Finnmark (Norway). LÄS MER

5. 9. Herbivores influence nutrient cycling and plant nutrient uptake : insights from tundra ecosystems

   Författare :Hélène Barthelemy; Olofsson Johan; Ellen Dorrepaal; Ann Milbau; Gough Laura; Umeå universitet; []
   Nyckelord :NATURVETENSKAP; NATURAL SCIENCES; Reindeer grazing; large herbivores; nutrient cycling; plant nutrient uptake; soil nutrient availability; arctic plant ecology; soil microbial communities; 15N stable isotopes; plant-soil interactions; plant quality; dung and urine.; Environmental Science; miljövetenskap; biology; biologi;

   Sammanfattning : Reindeer appear to have strong positive effects on plant productivity and nutrient cycling in strongly nutrient-limited ecosystems. While the direct effects of grazing on vegetation composition have been intensively studied, much less is known about the indirect effect of grazing on plant-soil interactions. LÄS MER

7. 10. Monitoring forest damage : methods and development in Sweden

   Författare :Sören Wulff; Sveriges lantbruksuniversitet; Sveriges lantbruksuniversitet; []
   Nyckelord :LANTBRUKSVETENSKAPER; AGRICULTURAL SCIENCES;

   Sammanfattning : The aims of the work this thesis is based upon were to assess past and current methods of monitoring forest damage in Sweden and to propose key components of a new monitoring system that would be better adapted to the information requirements. A utilitarian perspective is adopted in the thesis, thus forest damage is defined as anything that reduces the vitality of trees in a forest or their economic value. LÄS MER