The shift in forest and tree limits in Troms County - with a main focus on temperature and herbivores
To better understand how various factors affect the establishment of forest and trees around the tree line-ecotone, this study was conducted in Troms County, Norway. The altitude of different forest and tree limits together with the surrounding vegetation type were collected during August 2011. Comp...
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| Formato: | H2 |
| Lenguaje: | Inglés sueco |
| Publicado: |
SLU/Dept. of Wildlife, Fish and Environmental Studies
2012
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| Materias: |
| _version_ | 1855570627055845376 |
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| author | Normark, Kristoffer |
| author_browse | Normark, Kristoffer |
| author_facet | Normark, Kristoffer |
| author_sort | Normark, Kristoffer |
| collection | Epsilon Archive for Student Projects |
| description | To better understand how various factors affect the establishment of forest and trees around the tree line-ecotone, this study was conducted in Troms County, Norway. The altitude of different forest and tree limits together with the surrounding vegetation type were collected during August 2011. Comparisons of the collected data were made with previously collected data from the same sites conducted 1914 and 1915. On average the forest limit has expanded with 26 meters in altitude, however, an expansion is not statistically significant for the whole area. The tree limit has significantly expanded in altitude. At all weather stations the temperature sum and length of the growing season have increased which is proposed to have positive effects on sapling establishment. There is no significant correlation between the change in sheep density in relation to the shift in forest and tree limit. The shift in reindeer density did not correspond to the shift of forest limit, but to the shift in tree limit. However the coefficient of determination was low which means that reindeer only accounts for a small part of the altitudinal shift. At many sites where the tree limit has expanded, reindeer density has declined which might have provided for new plants to establish and older to grow in size. The altitude of the forest and tree limits increases with increasing distance to the coast, most likely due to the degree of maritimity. It should also be noted that the magnitude of the shift in the limits, decrease with increasing distance to the coast. With reduced amount of reindeers and increased temperature vegetation changes have occurred. The amount of birch forest has increased, most likely, in expense of declined willow-thickets. Also abundance of alpine lichen/moss heath has increased, which might be a result of reduced grazing by reindeers.
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| format | H2 |
| id | RepoSLU4044 |
| institution | Swedish University of Agricultural Sciences |
| language | Inglés swe |
| publishDate | 2012 |
| publishDateSort | 2012 |
| publisher | SLU/Dept. of Wildlife, Fish and Environmental Studies |
| publisherStr | SLU/Dept. of Wildlife, Fish and Environmental Studies |
| record_format | eprints |
| spelling | RepoSLU40442012-04-20T14:26:00Z The shift in forest and tree limits in Troms County - with a main focus on temperature and herbivores Förändringen av skog- och trädgränser i Troms fylke - med fokus på temperatur och herbivorer Normark, Kristoffer forest limit tree limit temperature herbivore To better understand how various factors affect the establishment of forest and trees around the tree line-ecotone, this study was conducted in Troms County, Norway. The altitude of different forest and tree limits together with the surrounding vegetation type were collected during August 2011. Comparisons of the collected data were made with previously collected data from the same sites conducted 1914 and 1915. On average the forest limit has expanded with 26 meters in altitude, however, an expansion is not statistically significant for the whole area. The tree limit has significantly expanded in altitude. At all weather stations the temperature sum and length of the growing season have increased which is proposed to have positive effects on sapling establishment. There is no significant correlation between the change in sheep density in relation to the shift in forest and tree limit. The shift in reindeer density did not correspond to the shift of forest limit, but to the shift in tree limit. However the coefficient of determination was low which means that reindeer only accounts for a small part of the altitudinal shift. At many sites where the tree limit has expanded, reindeer density has declined which might have provided for new plants to establish and older to grow in size. The altitude of the forest and tree limits increases with increasing distance to the coast, most likely due to the degree of maritimity. It should also be noted that the magnitude of the shift in the limits, decrease with increasing distance to the coast. With reduced amount of reindeers and increased temperature vegetation changes have occurred. The amount of birch forest has increased, most likely, in expense of declined willow-thickets. Also abundance of alpine lichen/moss heath has increased, which might be a result of reduced grazing by reindeers. För att bättre förstå hur olika faktorer påverkar etableringen av skog och träd i och kring trädgränsen, utfördes denna studie i Troms fylke, Norge. Altituden av olika skogs och trädgränser samt vegetationen 200 meter nedan och ovan respektive gräns, samlades in under augusti månad 2011. Jämförelser av det insamlade data gjordes med tidigare insamlat data från samma platser utfört 1914 och 1915. Skogsgränsen har i genomsnitt expanderat med 26 meter i altitud, men en expansion för hela området är inte statistiskt signifikant. Trädgränsen har expanderat vilket är statistiskt signifikant. På samtliga väderstationer har både temperatursumman och växtperiodens längd ökat vilket tros ha en positiv påverkan på plantornas etablering. Det finns ingen signifikant korrelation mellan förändringen av ren och förändringen av skog och trädgräns. Inget signifikant samband erhölls för förändring ren och förändring skogsgräns, men ett signifikant samband erhölls mellan rendensitet och förändringen av trädgränsen. Dock var förklaringsgraden låg vilket betyder att ren endast förklarar en liten del av förändringen av trädgränsen. Vid flertalet av de trädgränser som expanderat har rendensiteten minskat vilket kan betyda att en minskning i renantal möjliggjort för nya trädindivider att etablera sig samt gamla att tillväxa. Altituden för skogs- och trädgränser ökar med ökat avstånd från kusten mest troligt på grund av en maritim gradient. Vidare kan konstateras att storleken på gränsernas förändring minskar med ökat avstånd till kusten. Med minskat antal ren och ökad temperatur har vegetationen förändrats. Mängden björkskog har ökat, mest troligt, på bekostnad av videsnårklassen. Mängden lav- och mosshed har ökat, vilket kan bero på minskat bete av ren. SLU/Dept. of Wildlife, Fish and Environmental Studies 2012 H2 eng swe https://stud.epsilon.slu.se/4044/ |
| spellingShingle | forest limit tree limit temperature herbivore Normark, Kristoffer The shift in forest and tree limits in Troms County - with a main focus on temperature and herbivores |
| title | The shift in forest and tree limits in Troms County - with a main focus on temperature and herbivores |
| title_full | The shift in forest and tree limits in Troms County - with a main focus on temperature and herbivores |
| title_fullStr | The shift in forest and tree limits in Troms County - with a main focus on temperature and herbivores |
| title_full_unstemmed | The shift in forest and tree limits in Troms County - with a main focus on temperature and herbivores |
| title_short | The shift in forest and tree limits in Troms County - with a main focus on temperature and herbivores |
| title_sort | shift in forest and tree limits in troms county - with a main focus on temperature and herbivores |
| topic | forest limit tree limit temperature herbivore |