Birch sapling characteristics growing beyond the tree line in Norway and Sweden

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Hauptverfasser: Hofgaard, Annika, Dalen, Linda, Hytteborn, Håkan
Format: Dataset Open Access
Sprache:en
Veröffentlicht: PANGAEA 2009
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author Hofgaard, Annika
Dalen, Linda
Hytteborn, Håkan
author_facet Hofgaard, Annika
Dalen, Linda
Hytteborn, Håkan
collection Datos científicos de ciencias marinas y ambientales
contents Questions: How do population structure and recruitment characteristics of Betula saplings beyond the treeline vary among climatic regions, and what is the potential for development into tree-sized individuals with interacting grazing pressure? Location: Scandes Mountains. Methods: Sapling characteristics of Betula pubescens subsp. tortuosa, their topographic position above the treeline, growth habitat and evidence of recent grazing was investigated in three areas with a long continuous grazing history, along a latitudinal gradient (62-69°N). Results: Saplings were common up to 100 m above the treeline in all areas. The northern areas were characterised by small (<30 cm) and young (mean 14 years old) saplings in exposed micro-topographic locations unfavourable to long-term survival. In the southern area, broad height (2-183 cm) and age (4-95 years; mean 32 years) distributions were found in sheltered locations. Age declined with altitude in all areas. Sapling growth rate varied within and between areas, and the age x height interaction was significant only in the southern area. Growth rates decreased from south to north and indicated a considerable time required to reach tree size under prevailing conditions. Conclusions: Regional differences can be attributed to climatic differences, however, interacting biotic and abiotic factors such as micro-topography, climate and herbivory, mutually affect the characteristics of birch saplings. In view of the long time needed to reach tree size, the generally expected evident and fast treeline advance in response to climate warming may not be a likely short-term scenario. The sapling pool in the southern region possesses strongest potential for treeline advance.
format Dataset Open Access
id pangaea_https___doi_org_10_1594_PANGAEA_811218
institution PANGAEA
language en
publishDate 2009
publisher PANGAEA
record_format pangaea
spellingShingle Birch sapling characteristics growing beyond the tree line in Norway and Sweden
Hofgaard, Annika
Dalen, Linda
Hytteborn, Håkan
International Polar Year (2007-2008); IPY
Questions: How do population structure and recruitment characteristics of Betula saplings beyond the treeline vary among climatic regions, and what is the potential for development into tree-sized individuals with interacting grazing pressure? Location: Scandes Mountains. Methods: Sapling characteristics of Betula pubescens subsp. tortuosa, their topographic position above the treeline, growth habitat and evidence of recent grazing was investigated in three areas with a long continuous grazing history, along a latitudinal gradient (62-69°N). Results: Saplings were common up to 100 m above the treeline in all areas. The northern areas were characterised by small (<30 cm) and young (mean 14 years old) saplings in exposed micro-topographic locations unfavourable to long-term survival. In the southern area, broad height (2-183 cm) and age (4-95 years; mean 32 years) distributions were found in sheltered locations. Age declined with altitude in all areas. Sapling growth rate varied within and between areas, and the age x height interaction was significant only in the southern area. Growth rates decreased from south to north and indicated a considerable time required to reach tree size under prevailing conditions. Conclusions: Regional differences can be attributed to climatic differences, however, interacting biotic and abiotic factors such as micro-topography, climate and herbivory, mutually affect the characteristics of birch saplings. In view of the long time needed to reach tree size, the generally expected evident and fast treeline advance in response to climate warming may not be a likely short-term scenario. The sapling pool in the southern region possesses strongest potential for treeline advance.
title Birch sapling characteristics growing beyond the tree line in Norway and Sweden
topic International Polar Year (2007-2008); IPY
url https://doi.org/10.1594/PANGAEA.811218