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Research article2009Peer reviewed

Effects of different levels of green- and dead-tree retention on hemi-boreal forest bird communities in Sweden

Soderstrom, Bo

Abstract

Partial clear-cut harvesting techniques - where variable amounts of green and dead trees are retained on retention cuts - have replaced clear-cutting as the standard practice in boreal forest ecosystems to meet environmental goals. Recent meta-analyses have suggested that a green-tree retention level below 15% of the original tree density has no or only weak positive effects on pre-harvest forest bird abundances. In comparison, certification organisations in Sweden prescribe retention of <2% of pre-harvest tree density. Furthermore, previous research has largely ignored potential partial clear-cutting effects on fauna and flora in adjacent, non-logged forests. This study investigated how breeding birds on retention cuts and in adjacent forest responded to a continuous tree retention gradient on retention cuts varying from <1% to 25%. A total of 1843 bird territories of 59 species were found on 54 retention cuts. In general, most early successional bird species (characteristic of more or less open habitats) were significantly positively associated with retention cut size and negatively associated with green-tree retention. In contrast, the abundances of late-successional forest bird species were not significantly associated with retention cut size but strongly preferred cuts with higher retention levels, especially of deciduous and dead trees. A retention level of about 10% of pre-harvest tree density would almost double the number of territories of resident forest passerines compared to current retention prescriptions. Furthermore, breeding birds were also affected by tree retention in adjacent, non-logged forests: total density of eight resident passerines was lower in the forest edge (0-50 m) adjacent to cuts with 0-2% compared to 10-20% of the original tree density. This suggests that few, large-sized retention cuts may reduce adverse edge effects better than many, small-sized retention cuts, and thus decreasing the landscape area affected by cutting practices. (C) 2008 Elsevier B.V. All rights reserved.

Keywords

Clear-cut; Green-tree retention; Dispersed retention; Group retention; Resident bird species; Neighbouring stands

Published in

Forest Ecology and Management
2009, Volume: 257, number: 1, pages: 215-222 Publisher: Elsevier

    UKÄ Subject classification

    Forest Science
    Environmental Sciences related to Agriculture and Land-use

    Publication identifier

    DOI: https://doi.org/10.1016/j.foreco.2008.08.030

    Permanent link to this page (URI)

    https://res.slu.se/id/publ/20931