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Table 1 Windthrow in variable retention trials and operational cutblocks in British Columbia

From: Two decades of variable retention in British Columbia: a review of its implementation and effectiveness for biodiversity conservation

Study name Ecological conditionsa Retention type Yearsb Wind damagec Citation
Operational VR, Clayoquot Sound, BC Hypermaritime CWH Dispersed, Aggregated, Mixed 1–6 16.5% of 1215 stems in various types Increased with percent of trees harvested; Dispersed > Aggregated Scott and Mitchell 2005
STEMS 2– Campbell River, BC Very Dry Maritime CWH Dispersed, Aggregated, Other systems 2 Dispersed 40 stems/ha (5%): 24% Small aggregates (0.05 ha): 54% Thinning (64% volume removed): 18% Group selection (25% removed): 5% Patch cuts (25% removed): 6% Control (unharvested): 8% Aggregated > Dispersed deMontigny and Nigh 2009, Byrne and Mitchell 2013
MASS—Campbell River, BC Montane CWH Dispersed, Aggregated Shelterwood 6 Dispersed 25 stems/ha: 29% Large aggregates (1.5 ha): 2% Shelterwood (25% basal area retained): 10% Dispersed > Aggregated Beese 2001
Operational VR—Kispiox Forest District, BC Moist Cold ICH Wet Submaritime Montane CWH Aggregated 12–16 Aggregates (0.8 ha avg.): 9% Less windthrow in larger aggregates Steventon 2011
Operational VR, Weyerhaeuser/Western, AM Monitoring, Coastal BC Hypermaritime, Maritime, Montane CWH Aggregated, Mixed 2–5 Small to medium aggregates (0.22 ha avg.): 37% (23–53%) Large aggregates (> 1 ha): 24% (16–45%) Less windthrow in larger aggregates Beese et al. 2019
  1. aBiogeoclimatic zones and subzones: CWH Coastal Western Hemlock zone, ICH Interior Cedar Hemlock zone; subzone names from Klinka et al. (1991); all areas are coastal except the ICH portion of Steventon (2011), which has forests similar to the CWH zone; other interior sites (Bulkley/Morice) in Steventon not shown
  2. bYears post-harvest when wind damage was assessed
  3. cPercent damage to retained stems within plots, entire aggregates or a defined strip along larger aggregates; percentages show the average and (range) among study areas or treatments for the cited studies