A simple model for estimating light environment in strip clear-cutting stands

Abstract

A simple model that estimates the light environments within a strip clear-cutting stand was derived. The sky factor was used as a measure of light environment. In order to derive the model, we assumed that: 1) the direction of the strip was parallel to the incline; 2) the strip width and length were constant and infinite, respectively; 3) the inclination angle was constant; and 4) walls, the height of which was equal to the mean height of residual stands, were erected on both sides of the strip. Driving variables in the model included the strip width, height of residual stands, position within the strip and inclination angle. In six strip clear-cutting stands, the sky factor estimated by the model was compared with that measured with hemispherical photography. In four of the six stands, there was no significant difference between estimated and measured sky factor. However, the sky factor in the other two stands was underestimated, since the model assumed that no light penetrated into the strip through the canopy of residual stands. Model simulation demonstrated that the inclination angle should be taken into account when estimating light environment in strip clear-cutting stands. The model presented here provides a simple means for estimating light environments in a strip clear-cutting stand, and thus it will be beneficial as a tool for developing a guideline for the strip clear-cutting.