Soil surface condition following tractor and high-lead logging in the Oregon Cascades

Abstract. Soil surface condition and bulk density were investigated after tractorand high-lead logging. Surface area of four clearcut units was classified intofour disturbance classes. High-lead and tractor areas had about the same pro-portion of the slightly disturbed and deeply disturbed classes (approximately23 percent and 9 percent, respectively). The tractor-logged area had aboutthree times more area within the compacted class than did the high-lead (27vs. 9 percent) and a corresponding decrease in the amount in the undisturbedclass (36 percent of the tractor area vs. 57 percent after high-lead logging).Surface soil bulk densities of samples from undisturbed and slightly disturbedareas were the same as prelogging values. Values for both the deeply disturbedand compacted classes were significantly higher, indicating a decrease in soilporosity. Compaction caused by tractor logging undoubtedly results in someincrease in runoff and erosion. However, these undesirable effects are minimizedif slopes do not exceed 20 to 30 percent and skidroads are located on thecontour.