INFLUENCE OF DECAYING WOOD ON CHEMICAL-PROPERTIES OF FOREST FLOORS AND SURFACE MINERAL SOILS - A PILOT-STUDY

Samples of forest floors and spodic horizons from pedons with and with out a large accumulation of decaying wood were collected from 2 forest stands in southwestern British Columbia. The samples were analyzed to determine chemical properties which would be useful measures of the p ossible influence of decaying wood on soil nutrient status and soil de velopment in subsequent studies. There were several significant differ ences between chemical properties of forest floors and those of spodic horizons. The most distinguishing characteristic of decaying wood see med to be high concentrations of humic acids (> 14%). Relative to the pedons without decaying wood, 1) the forest floors with decaying wood and the spodic horizons beneath were more acidic; 2) the spodic horizo n was lower in potassium, and in the case of the Douglas-iir stand, lo wer in calcium and magnesium as well; 3) greater accumulation of amorp hous inorganic aluminum in the spodic horizon occurred beneath decayin g wood in the western hemlock stand and 4) a greater tendency towards accumulation of amorphous organic aluminum and iron occurred beneath d ecaying wood in the Douglas-fir stand. It appears that the influence o f decaying wood on soils is site-specific and related to forest floor properties, such as acidity and the level of lipids and humic and fulv ic acids. Further comparative studies examining the influence of decay ing wood on soil nutrient status and soil development should be carrie d out using spatially independent replicated sampling and proposed soi l chemical analyses over a wide range of stands and soils.