Organic matter content of soil after logging of fir and redwood forests

Organic matter in soil controls a variety of soil properties. A study in Humboldt County, California, evaluated changes in percentages of organic matter in soil as a function of time after timber harvest and soil depth in fir and redwood forests. To assess organic matter content, samples were taken from cutblocks of various ages in soil to depths of 1.33 m. Results indicate that only depth correlated significantly with organic matter in the fir forest. Depth, and to a minor extent, age, con-elated significantly with organic matter content in the redwood forest. Organic matter content-in the redwood forest showed a small decline until 35 to 45 years after logging. These findings suggest that the adverse impact on soil organic matter due to logging is minor.