Pedogenesis in Western Washington and Northern Alaska: A Comparison of the Primary Factors
Pedology is partially based on the established principle that soil changes are directly correlated to specific biotic communities and regional climatic patterns. From this principle questions have arisen as to why the Arctic tundra that lies above the treeline in Alaska displays similar chemical characteristics to that of the well-developed Podzols and Spodosols found in the coniferous forests of Washington. The Podzols and Spodsols of these coniferous forests are defined by their cool and humid regional climates and by the acidic parent material from which they formed. Recent studies indicate that the E and Bs horizons that define the temperate forest soils are also found above the treeline in Alaska, Canada, Greenland, and Siberia (Ugolini, Stoner, & Marret, 1987). What role does biota play in the current soil formation for each of the sites? Why do the similarities exist between the sites despite differences in climate and vegetation? What other factors consistently influence the soil properties?
The purpose of my paper is to address the question of which soil forming factors have the greatest effect on the similar and distinct characteristics of the two geographic locations.
Podzolization: Pedogenic Change in Alaska and Washington
Chemical analyses of temperate forest soils in the Pacific Northwest have been collected to examine soil forming trends (Ugolini, Stoner, & Marret, 1987). Such data allows us to compare various ecosystems and their characteristic pedological processes. Ugolini et al 1987 show how the soil solution analysis allows us to see ". . . a simple two-compartment system" (p.91). The first part of the system analyzes the layers most affected by the biota which include the O and A horizons (the elluvial level). Thus, the second "compartment" looks at the illuviated material, the soluble organics and metal cations, in the B horizons. This compartmentalized system allows one to use dynamic pedology, the comparison and analysis of soil solutions, to look at soil forming processes.
With this method Ugolini, Stoner, & Marret research and sample two sites in Northern Alaska and then compare them to previously collected data from Washington. The parent material of the Alaskan sites consists of granitic glacial drift deposited approximately 15,000 years BP. Walter Lake and Okpilak, both have a below 0 degree Celsius annual temperature average and 337 mm and 169 mm, respectively of average annual precipitation (1987). The vegetation at Walter Lake was primarily spruce while the dominant species at Okipilak were lichen and dwarfed heath. The boreal forests of Washington show an increase in several variables (as reflected in the slope line of Fe, Al, and DOC) between the data collected for two compartments (see figure 3). This is due to the fact that organic acids are present in the higher horizons and thus, cause...