Action: Use variable retention management during forestry operations
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A replicated, controlled study from the USA found that nine bird species occurred at higher densities in stands under variable retention management, compared to control stands. Five were found at lower densities.
Variable retention timber management is a silvicutural technique designed to retain habitat features important for wildlife e.g. large trees, snags and woody debris. This method of harvesting does not seek to maximize timber production.
Supporting evidence from individual studies
A replicated, controlled study in the summers of 2003-2004 in bottomland hardwood forest on Tensas River National Wildlife Refuge, Louisiana, USA (Twedt & Somershoe 2009), found that densities of nine species of birds (six of conservation concern) were higher in stands under variable-retention timber harvests, compared to control (untreated) stands. Densities of five species were greater in untreated stands. Conservation concern scores and detection rates of 30 species, suggest that the mosaic of treated stands afforded greater community-wide bird conservation value than untreated stands. Bird densities were estimated (distance sampling) within forest subject to variable-retention harvests within a 13-year chronosequence (i.e. a set of forested sites with similar attributes but of different ages), and untreated stands.