CONTEMPORARY FOREST MANAGEMENT AND MASS WASTING; MAKING SIGNIFICANT PROGRESS

The degree to which timber harvesting and related management practices influence mass wasting has changed dramatically over the last two decades and are now more carefully assessed and mitigated than ever before. As part of a recent mass wasting assessment on industrially managed timberlands in northern California, we reviewed 70 years of historic aerial photographs from 1940-2012 and measured over 2,900 shallow landslides in the field. Although landsliding is influenced by factors that on a decadal scale are stochastic in occurrence, the observations to date strongly indicate the new regulations, habitat conservation plans, and geologic oversight have made significant positive impacts on the degree to which timber management practices have affected regional mass wasting. Our study indicates shallow landslide erosion rates have dropped more than 90% since the peak rates that were observed in the 1970’s. Currently, decadal erosion rates are at their lowest (0.16 m³/ha/yr) over the period of photographic record that was reviewed for this study.