These effects on tree growth, which may persist for several decades (Hatchell et al. 1970, Butt 1987, Miller et al. 1996), may lead to shortand long-term reductions in tree growth and forest productivity. The level of soil disturbance will vary with soil texture, forest floor thickness, and soil water content at time of harvest (Miller and Sirois 1986, Corns 1988). In addition, machine type, si...