Graduation Date
Fall 2022
Document Type
Thesis
Program
Master of Science degree with a major in Natural Resources, option Forestry, Watershed, & Wildland Sciences
Committee Chair Name
Hunter Harrill
Committee Chair Affiliation
HSU Faculty or Staff
Second Committee Member Name
Susan Edinger Marshall
Second Committee Member Affiliation
HSU Faculty or Staff
Third Committee Member Name
Andrew Stubblefield
Third Committee Member Affiliation
HSU Faculty or Staff
Fourth Committee Member Name
Han-Sup Han
Fourth Committee Member Affiliation
Community Member or Outside Professional
Subject Categories
Forestry
Abstract
The implementation of tethered harvesting allows for the expansion of mechanized logging onto steeper slopes. Recent updates to the California Forest Practice Rules have explicitly removed the slope limitation for logging equipment, provided it’s tethered. California is now witnessing the reintroduction of ground-based logging equipment on steep slopes. Previously, operating equipment on steep slopes was considered detrimental due to the potential for soil disturbance. However, tethered equipment interacts with the soil in a new way due to the use of a winch. Relatively few studies have attempted to quantify soil disturbance with this new practice. The goal of this study was to quantify the severity and extent of soil disturbance from two different tethered harvesting operations on steep slopes in Northern California: a whole-tree operation and a cut-to-length operation. Extent of visual soil disturbance was assessed through visual classifications of soil disturbance based on a relative scale considering rutting, mounding, and mineral soil exposure. The severity of compaction was determined by measuring the change in bulk density along machine trails. Soil samples were collected along the machine trail at equally spaced intervals from between tracks, under track treads, and undisturbed soil adjacent to the machine trail, at three different depths: 10 cm, 20 cm, and 30 cm. The whole-tree operation did not see any statistically significant changes in bulk density while the cut-to-length operation saw a statistically significant increase of 12.8% at the 10 cm depth under the track tread. Of all the collected soil samples in both sites, 60% had some degree of compaction while 40% had some degree of loosening. The visual disturbance was highest in the whole-tree operation, with 15% of the corridor showing the highest class of visual disturbance. The most detrimental visual disturbance was found near the top and bottom of the trail, where there was an abrupt change in grade, while the cut-to-length operation had fewer areas of concerning visual disturbance. Statistical analysis suggests that the soil and site characteristics such as slope, rock volume, and organic matter influence how susceptible a site is to soil compaction and the extent to which soils are visually disturbed.
Citation Style
APA
Recommended Citation
Fagundes, Karolyn Marie, "Assessing soil disturbance from tethered logging on steep slopes in Northern California" (2022). Cal Poly Humboldt theses and projects. 591.
https://digitalcommons.humboldt.edu/etd/591