Tuesday, 8 November 2005
17

Microtopographical and Pedogenic Properties of Southeast Alaskan Folists.

Becki L. Saari1, Paul McDaniel1, Anita Falen1, and David D'Amore2. (1) University of Idaho, Ag Science, Box 442339, 6th and Rayburn Streets, Moscow, ID 83844-2339, (2) US Forest Service - Pacific Northwest Research Station, 2770 Sherwood Lane Ste 2A, 2770 Sherwood Lane Ste 2A, Juneau, AK 99801

Dysic Lithic Cryofolists of southeast Alaska are all categorized as the McGilvery soil series regardless of the underlying bedrock type. This study was conducted to determine the different physical and chemical properties of these soils overlying different bedrock types and how these properties are influenced by pedogenic processes and factors. Lithic Cryofolists (the McGilvery soil series) overlying volcanic and limestone (karst) bedrock types on Prince of Wales Island were investigated through a combination of field observations and laboratory analyses. Lithic Cryofolists of karst topography have higher pH in the subsurface horizons than at the surface. The opposite trend was observed in Cryofolists overlying volcanic rock. Cryofolists of karst topography have pH values as high as 5.9 compared to a low of 2.5 for Folists of volcanic landscapes. Shallow soils overlying karst have the highest pH values and lowest organic matter and C:N ratios. Karst landscapes have better drainage and more topographical undulation, and the soils have greater concentration of exchangeable cations with increasing depth compared to the volcanic terrain. Soils of karst topography exhibit considerable depth variation across short lateral distances, while more consistent soil depths are observed with Folists of the volcanic landscapes. All of the Cryofolists show an increase of secondary aluminum and iron with depth. The different bedrock types appear to have an influence on the chemical and physical properties of these soils, thereby affecting fertility, vegetation, and management. Results of this study indicate that Lithic Cryofolists (McGilvery) in southeast Alaska should be further delineated into additional soil series by bedrock type.

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