Abstract
Previous studies on the relationship between logging operations and soil and water
conservation are rare in Taiwan. This study attempted to measure environmental
characteristics and hydrological responses in a non-logged plot and row-thinned plots
including clear-cut and low-thinned areas in forest compartments nos. 87 and 88 in
the Zhudong working circle, Hsinchu Forest District. For observed results in the
near-surface environment, coverage of the understory showed no differences between
the clear-cut and low-thinned areas. Soil porosity in the near-surface layer was similar
among the clear-cut, low-thinned, and non-logged areas. However, logging operations
enlarged the variability of soil porosity. We found a higher surface soil water content in
clear-cut areas than in low-thinning areas. This was due to the larger amount of rainwater
reaching the surface in the clear-cut areas, where the amount of overland flow was greater
than that in low-thinned areas. For the underground environment, the spatial distribution of groundwater was little related to logging operations, but was mainly controlled by geological conditions, such as a separation interface of bedrock. We concluded that clear-cut and
low-thinned operations would greatly affect interactions of soil and water processes in the
region near the surface but not in the region of the bedrock layer. To reduce potential
influences of disturbances in the near-surface environment on the underground hydrological responses, it is unsuitable to set up clear-cut areas in valleys or geologically
sensitive areas.