Retain residual tree patches in logged areas
Overall effectiveness category Unknown effectiveness (limited evidence)
Number of studies: 2
Background information and definitions
Logging by clearcutting results in large open, cleared areas in forests (clearcut blocks). Residual tree patches may be left uncut within these areas.
Supporting evidence from individual studies
A replicated, site comparison study in 2000 at nine sites in an experimental forest in Alberta Canada (Hogberg et al 2002) found that the edges of residual tree patches had higher activity of smaller bat species than the centre of open clearcut blocks, but the activity of larger bat species did not differ. More bat passes of smaller bat species (calls detected at 45 kHz) were recorded along the edges of residual tree patches (average 4 bat passes/hour) and forest edges (5 bat passes/hour) than in the centre of open clearcut blocks (2 bat passes/hour). A similar number of passes of larger bat species (calls detected at 25 kHz) were recorded along residual tree patch edges, forest edges and in the centre of clearcut blocks (data not reported). Residual tree patches were oval (60 x 90 m). At each of nine clearcut blocks (8–10 ha, 1–2 years old), three locations were sampled (forest edge, residual patch edge, centre of clearcut block). Each of three locations within nine clearcut blocks was sampled for 15 minutes 2–3 times in a randomized order during one night in June–July 2000.Study and other actions tested
A replicated, site comparison study in 2000 of six sites in logged forest in central British Columbia, Canada (Swystun et al 2001) found that the edges of residual tree patches had similar bat activity to clearcut forest edges. Overall bat activity along residual tree patch edges (49 total bat passes) did not differ significantly to that along clearcut forest edges (110 bat passes). Six residual tree patches (0.5–2 ha) were sampled in six clearcut blocks (105–180 ha, <5 years old) in logged forest (dominated by lodgepole pine Pinus contorta). At each of six sites, bat activity was recorded with bat detectors simultaneously along residual tree patch edges and clearcut edges for one night in July–August 2000.Study and other actions tested