Forest edges in boreal landscapes - factors affecting edge influence
The boreal forest in Fennoscandia has been subjected to major loss and fragmentation of natural forests due to intensive forestry. This has resulted in that forest edges are now abundant and important landscape features. Edges have documented effects on the structure, function and biodiversity in fo...
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Ekologi, miljö och geovetenskap
2009
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ftumeauniv:oai:DiVA.org:umu-21664 2023-10-09T21:51:27+02:00 Forest edges in boreal landscapes - factors affecting edge influence Jansson, Ulrika 2009 application/pdf http://urn.kb.se/resolve?urn=urn:nbn:se:umu:diva-21664 eng eng Ekologi, miljö och geovetenskap http://urn.kb.se/resolve?urn=urn:nbn:se:umu:diva-21664 urn:isbn:978-91-7264-756-5 info:eu-repo/semantics/openAccess aerial photographs edge contrast edge density edge length fetch size forest fragmentation lichen growth line intersect sampling pendulous lichen photo interpretation skogskant flygbild kantlängd lav Ecology Ekologi Doctoral thesis, comprehensive summary info:eu-repo/semantics/doctoralThesis text 2009 ftumeauniv 2023-09-22T13:46:51Z The boreal forest in Fennoscandia has been subjected to major loss and fragmentation of natural forests due to intensive forestry. This has resulted in that forest edges are now abundant and important landscape features. Edges have documented effects on the structure, function and biodiversity in forests. Edge influence on biodiversity is complex and depends on interactions between many local and regional factors. This thesis focuses on sharp forest edges and their potential to influence biodiversity at the landscape-level. I have developed a method for quantification and characterization of sharp forest edges by interpretation of colour infrared (CIR) aerial photographs in combination with line intersect sampling (LIS) and sample plots. The method was used to estimate density of forest edge in 28 landscapes (each 1600 ha) in northern Sweden, differing in management intensity, landscape composition and geographical location. Forest edges were described in detail using edge, canopy and neighbourhood attributes. By combining these attributes it was possible to classify edges with respect to levels of exposure. A field experiment was conducted to examine the effect of edge contrast on growth of the old forest lichen Usnea longissima. The edge quantification method is accurate and efficient for estimating the length of sharp forest edges on an area basis (edge density, m ha-1) and for collecting detailed attributes of edges and their surroundings. In northern Sweden, the forest edge density is high (54 m ha-1) but varies extensively (12-102 m ha-1) between landscapes. Edge density is strongly correlated with the level of human disturbance and increases towards the southern part of the study area, at lower altitudes were management intensity is highest. Edge orientation, contrast and neighbourhood size shows an immense variation between edges and also varies between edge types. Regenerating edges are generally of higher contrast and face larger neighbourhoods than natural edges. Maintained edges had high contrast but ... Doctoral or Postdoctoral Thesis Fennoscandia Northern Sweden Umeå University: Publications (DiVA) |
institution |
Open Polar |
collection |
Umeå University: Publications (DiVA) |
op_collection_id |
ftumeauniv |
language |
English |
topic |
aerial photographs edge contrast edge density edge length fetch size forest fragmentation lichen growth line intersect sampling pendulous lichen photo interpretation skogskant flygbild kantlängd lav Ecology Ekologi |
spellingShingle |
aerial photographs edge contrast edge density edge length fetch size forest fragmentation lichen growth line intersect sampling pendulous lichen photo interpretation skogskant flygbild kantlängd lav Ecology Ekologi Jansson, Ulrika Forest edges in boreal landscapes - factors affecting edge influence |
topic_facet |
aerial photographs edge contrast edge density edge length fetch size forest fragmentation lichen growth line intersect sampling pendulous lichen photo interpretation skogskant flygbild kantlängd lav Ecology Ekologi |
description |
The boreal forest in Fennoscandia has been subjected to major loss and fragmentation of natural forests due to intensive forestry. This has resulted in that forest edges are now abundant and important landscape features. Edges have documented effects on the structure, function and biodiversity in forests. Edge influence on biodiversity is complex and depends on interactions between many local and regional factors. This thesis focuses on sharp forest edges and their potential to influence biodiversity at the landscape-level. I have developed a method for quantification and characterization of sharp forest edges by interpretation of colour infrared (CIR) aerial photographs in combination with line intersect sampling (LIS) and sample plots. The method was used to estimate density of forest edge in 28 landscapes (each 1600 ha) in northern Sweden, differing in management intensity, landscape composition and geographical location. Forest edges were described in detail using edge, canopy and neighbourhood attributes. By combining these attributes it was possible to classify edges with respect to levels of exposure. A field experiment was conducted to examine the effect of edge contrast on growth of the old forest lichen Usnea longissima. The edge quantification method is accurate and efficient for estimating the length of sharp forest edges on an area basis (edge density, m ha-1) and for collecting detailed attributes of edges and their surroundings. In northern Sweden, the forest edge density is high (54 m ha-1) but varies extensively (12-102 m ha-1) between landscapes. Edge density is strongly correlated with the level of human disturbance and increases towards the southern part of the study area, at lower altitudes were management intensity is highest. Edge orientation, contrast and neighbourhood size shows an immense variation between edges and also varies between edge types. Regenerating edges are generally of higher contrast and face larger neighbourhoods than natural edges. Maintained edges had high contrast but ... |
format |
Doctoral or Postdoctoral Thesis |
author |
Jansson, Ulrika |
author_facet |
Jansson, Ulrika |
author_sort |
Jansson, Ulrika |
title |
Forest edges in boreal landscapes - factors affecting edge influence |
title_short |
Forest edges in boreal landscapes - factors affecting edge influence |
title_full |
Forest edges in boreal landscapes - factors affecting edge influence |
title_fullStr |
Forest edges in boreal landscapes - factors affecting edge influence |
title_full_unstemmed |
Forest edges in boreal landscapes - factors affecting edge influence |
title_sort |
forest edges in boreal landscapes - factors affecting edge influence |
publisher |
Ekologi, miljö och geovetenskap |
publishDate |
2009 |
url |
http://urn.kb.se/resolve?urn=urn:nbn:se:umu:diva-21664 |
genre |
Fennoscandia Northern Sweden |
genre_facet |
Fennoscandia Northern Sweden |
op_relation |
http://urn.kb.se/resolve?urn=urn:nbn:se:umu:diva-21664 urn:isbn:978-91-7264-756-5 |
op_rights |
info:eu-repo/semantics/openAccess |
_version_ |
1779314554352697344 |