Soil properties and forest productivity can be affected by heavy equipment used for harvest and site preparation but these impacts vary greatly with site conditions and operational practices. We assessed the effects of ground‐based logging on soil physical properties and subsequent Douglas‐fir [Pseudotsuga menziesii (Mirb) Franco] growth on a highly productive site receiving vegetation control in coastal Washington. We also tested the effectiveness of tillage in maintaining or enhancing site productivity. On average, about half of the area of ground‐based harvested plots was affected by vehicular traffic. Sixty‐three percent of the trees were planted on microsites with some degree of soil disturbance. Soil bulk density at the 0‐ to 30‐cm depth increased from 0.63 to 0.82 Mg m−3 in the most compacted portions of traffic lanes. The area‐weighted increase in soil bulk density in the 0‐ to 30‐cm depth was 27%. Soil strength in traffic lanes increased at all depths < 55 cm but never exceeded 1300 kPa. Tillage to the 60‐cm depth returned the soil to its initial strength condition. Volumetric soil water content in compacted traffic lanes was greater than that in noncompacted soil. Total soil porosity decreased 10 to 13% with compaction, while available water holding capacity increased. In compacted soil, macropore space was reduced 40 to 52%. The study revealed no detrimental effects on tree height and diameter from soil compaction at age 4. At stand age 3, a tree volume index was actually greater for trees planted on traffic lanes than for those on non‐disturbed soil.

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The Forest Service of the U.S. Department of Agriculture is dedicated to the principle of multiple use management of the Nation's forest resources for sustained yields of wood, water, forage, wildlife, and recreation. Through forestry research, cooperation with the States and private forest owners, and management of the National Forests and national grasslands, it strives-as directed by Congress-to provide increasingly greater service to a growing Nation.The U.S. Department of Agriculture (USDA) prohibits discrimination in all its programs and activities on the basis of race, color, national origin, age, disability, and where applicable sex, marital status, familial status, parental status, religion, sexual orientation, genetic information, political beliefs, reprisal, or because all or part of an individual's income is derived from any public assistance program. (Not all prohibited bases apply to all programs.) Persons with disabilities who require alternative means for communication of program information (Braille, large print, audiotape, etc.) should contact USDA's TARGET Center at (202) 720-2600 (voice and TDD).To file a complaint of discrimination, write USDA, Director, Office of Civil Rights, 1400 Independence Avenue, S.W. Washington, DC 20250-9410 or call (800) 795-3272 (voice) or (202)