Logging in the Streamside Management Zone: Effects of Harvesting System and Intensity on Visual Soil Disturbance

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Date
2006-09-19
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Virginia Tech
Abstract

Streamside management zones (SMZs) are a common and effective mechanism used to protect and maintain water quality during timber harvesting operations. In the southeastern United States timber harvesting is typically allowed inside the SMZ, but there is little information regarding suitable types of harvesting systems and the acceptable amount of canopy cover. The effects of two harvesting systems and harvesting intensities on visual soil disturbance were evaluated throughout Virginia and eastern West Virginia. The harvesting systems were a chainsaw/cable-skidder system (manual) and a feller-buncher/grapple-skidder system (mechanized). A total of 118 unique SMZ plots were measured at 50 different harvest sites, split evenly between manual and mechanized operations. Analyses of variance (ANOVA) at the p < 0.10 significance level indicated that there was no significant difference in visual indices of soil disturbance levels between the two systems. However, the manual system had significantly more "rutted" disturbed area and slash cover than the mechanized system. Harvesting intensity was found to be a significant factor in the occurrence of total visual soil disturbance (slight, deep, rutted classes). Slope gradient was evaluated and revealed that slope percentages had no significant effect on percent soil disturbance for this study. Based on the parameters measured, the general occurrence and frequency of soil disturbance generally depends on the specific site conditions.

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Keywords
harvesting intensity, harvesting system, SMZ, visual soil disturbance
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