Masters Thesis

The effect of overstory canopy density alterations on air temperature in a managed redwood forest

This study was conducted to describe the relationship between air temperature and overstory canopy density within second growth redwood that was clearcut harvested in the 1920's. Following an initial 30-day monitoring period, the canopy surrounding three study plots was cut to create a 200-foot radius circle from a central control point. Thirty days later a second cut brought the radius width to 150-feet, and after another thirty days a third cut was made to reduce the overstory canopy to 85% crown closure between the 50- and 150-foot radius circles, leaving the inner 50-foot circle untouched. To determine if there was an effect on the air temperature 17 temperature data loggers were installed in each plot. These loggers were spaced 50-feet apart along the four cardinal directions. The center point of the innermost 50-foot circle served as a reference for comparison purposes. The daily mean, minimum, and maximum temperature difference between the 48 sampling points and their reference point in the untouched 50-foot areas of each plot was found following each harvesting event. No significant changes in the air temperature in the 50-foot untouched area resulted from any of the harvests (p 0.001). There was a strong relationship between the maximum daily air temperature differences and overstory canopy as measured by the solar pathfinder (R2= 0.66).

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