Soil-Vegetation Relationships in Franciscan Terrain of Northwestern California
- J. H. Popenoe ,
- K. A. Bevis,
- B. R. Gordon,
- N. K. Sturhan and
- D. L. Hauxwell
National Park Service, Redwood National Park, P.O. Box 7, Orick, CA 95555
Dep. of Geosciences, Oregon State Univ., Corvallis, OR 97331
USDA Soil Conservation Service, 273 E. Lakin Dr., Suite 7, Flagstaff, AZ 86004
Washington State Dep. of Natural Resources, 1007 S. Washington, Olympia, WA 98504
Dep. of Natural Resources, Humboldt State Univ., Arcata, CA 95521
This study sought to discover how soil and vegetation patterns are related in the mountains of northwestern California. Soils were compared by vegetation-epipedon type and drainage class, with elevation as a covariate. Vegetation types were (i) open prairie, (ii) coniferinvaded prairie, (iii) oak woodland, (iv) conifer forest with umbric or mollic epipedon, and (v) conifer forest with ochric epipedon. The level of organic carbon (OC) was similar in the upper 10 cm of mineral soil under all vegetation types, but soils under forest and oak woodland had less cumulative OC and N, and a greater decrease with depth than soils under prairie. Ochric epipedons under forest had wider C/N ratios than umbric and mollic epipedons under other vegetation types. Exchangeable Ca2+ and base saturation decreased with increasing elevation. Exchangeable Ca2+ decreased with depth under oak woodland and forest, and pH decreased with depth under oak woodland. Under prairie, pH increased with depth, and Ca2+ exhibited little change. Soils under prairie and invaded prairie had lower exchangeable K+ in upper horizons than soils under forest or oak woodland. Drainage-impaired subsoils had higher bulk density, pH, and exchangeable Ca2+ than well-drained subsoils. Conifer invasion was restricted to well-drained soils. Except for conifer-invaded prairie, closely associated soil and vegetation patterns indicated that the vegetation mosaic has persisted for a long time.Please view the pdf by using the Full Text (PDF) link under 'View' to the left.
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