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Research article - Peer-reviewed, 2020

Detection of Retention Trees on Clearcuts, a 50-Year Perspective

Holmström, Emma; Nordström, Ellen; Lariviere, Delphine; Wallin, Ida

Abstract

Changes in clearcut management over time were evaluated using aerial photographs taken between 1960 and 2010. Temporal changes were analysed in two different climatic zones in Sweden: a typical boreal forest zone (the coast of Västerbotten County), and the hemi-boreal zone of southern Sweden (represented by Kronoberg County). The study covers the periods before and after the paradigm shift in Swedish forestry caused by the equalization of the production and nature conservation objectives specified in the first paragraph of the Swedish Forestry Act. Photographs were processed to determine clearcut size and shape and to register solitary retention trees and groups of retention trees. Small but significant changes in clearcut size were detected over time. The number of retention trees increased over time, a result that was also found in other studies using different methodologies. The results demonstrate that measurable structural changes have occurred in Swedish forests over the 25 years since the paradigm shift. Results from this study also show that digital detection of green tree retention could be a future complement to field inventory and monitoring.

Keywords

Forestry; Clearcut; Aerial Photographs; Swedish Forestry Model; Retention Forestry

Published in

Open Journal of Forestry
2020, Volume: 10, number: 1