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DEMO Home > Research > Vegetation > Postharvest > Tree Damage
Research
Vegetation—Postharvest: Effects of Varying Levels and Patterns of Green-Tree Retention On Amount of Harvesting Damage
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John R. Moore1, Douglas A. Maguire2 1Department of Forest Resources
3College of Forest Resources |
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We provide a brief overview of this work below. For full text see:
Moore, J.; Maguire, D.; Phillips, D.; Halpern, C. 2002. Effects of varying levels and patterns of green-tree retention on amount of harvesting damage. Western Journal of Applied Forestry. 17: 202-206.
In this study, we assessed the magnitude and distribution of tree bole damage resulting from implementation of the retention harvest treatments that make up the DEMO experiment (see Treatment Implementation and Experimental Design).
Among the six study blocks (see Study Area), Douglas-fir (Pseudotsuga menziesii (Mirb.) Franco) and western hemlock (Tsuga heterophylla (Raf.) Sarg.) made up 75 percent of all measured trees (55 and 20 percent, respectively), and the proportion of trees damaged was similar for both species. Suppressed trees tended to be more susceptible to damage than were trees in other crown classes (table 1).
Table 1—Distribution of fresh scars by crown class
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Crown Class
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All trees
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Damaged trees
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Percentage of total trees
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Percentage within crown class
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Percentage of all damaged trees
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| Dominant |
4.1
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3.5
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2.2
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| Co-dominant |
42.3
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6.0
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39.6
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| Intermediate |
19.2
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5.8
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17.3
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| Supressed |
32.7
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8.1
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40.9
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| Unknown / dead |
1.7
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0.0
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0.0
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A greater proportion of trees in the dispersed-retention treatments were damaged than in the aggregated treatments (table 2). Only in the two dispersed-retention treatments were levels of damage significantly different from the controls (p<0.05). The greatest proportion of damaged trees occurred in the 15-percent dispersed-retention treatment and was likely due to the wider dispersion and higher intensity of felling and yarding operations associated with this treatment. The pattern of damage across treatments was similar for both small (≤25 cm d.b.h.) and large (>25 cm d.b.h.) trees. Some evidence was also found that sites with gentler slopes had less damage than those with steeper topography.
Table 2—Proportion of trees with fresh scars among the six experimental treatments
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Treatment
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All trees
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Trees ≤25 cm d.b.h.
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Trees >25 cm d.b.h.
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Percent
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| 100-percent control |
0.8
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1.1
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0.6
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| 75-percent aggregated |
2.2
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3.4
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1.3
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| 40-percent dispersed |
17.0*
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18.1*
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15.4*
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| 40-percent aggragated |
2.4
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2.7
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2.3
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| 15-percent dispersed |
27.2*
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25.0*
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29.3*
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| 15-percent aggragated |
1.6
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1.7
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1.8
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Means with an asterisk differ significantly (p<0.05) from the control. Fresh scars in the control treatment may reflect wind damage.
Given these initial patterns of harvest-related damage, we expect that the future incidence of stem rot and growth reductions will be greatest in the dispersed-retention treatments.
US Forest Service - Pacific Northwest Research Station, Demonstration
of Ecosystem Management Options
Last Modified: Thursday,27March2008 at12:39:30EDT