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USGS · 70195637

Low thinning and crown thinning of two severities as restoration tools at Redwood National Park

Jason R Teraoka·Phillip J. van Mantgem·Christopher R. Keyes
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Abstract

Interest in the restoration of second-growth forests has continued to increase in the redwood region, which has further increased the importance of evaluating restoration-based silvicultural strategies. This study assessed the short-term effectiveness of four silvicultural treatments (two silvicultural thinning methods, low thinning and crown thinning, and two basal area retentions, 80 percent and 45 percent) as forest restoration tools via analysis of relative basal area growth at Redwood National Park. Prior to treatment, the second-growth stand had more than 1,600 trees ha -1 and 70.0 m 2 ha -1 basal area and consisted primarily of two species, Douglas-fir ( Pseudotsuga menziesii (Mirb.) Franco) (the dominant species) and redwood ( Sequoia sempervirens (D. Don) Endl.). Growth was enhanced for all treatments with 5-year net basal area gains of 28.4 percent for the lowretention crown thinning, 28.1 percent for the low-retention low thinning, 23.3 percent for the high-retention crown thinning, 19.1 percent for high-retention low thinning, and only 14.2 percent for the control. We conclude that all four thinning treatments improved tree growth; but among them, the low-retention treatments were most effective in accomplishing restoration objectives, while the high-retention low thinning was least effective. Increasing the array of silvicultural tools that Redwood National Park can use may prove helpful in accomplishing restoration goals in future projects.

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Jason R Teraoka, Phillip J. van Mantgem, Christopher R. Keyes. 2017. Low thinning and crown thinning of two severities as restoration tools at Redwood National Park. https://pubs.usgs.gov/publication/70195637

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