Determination of humus stocks and qualities of forest floors in pure and mixed stands of spruce and beech.

摘要

Investigations about humus stocks and depth gradients of soil organic matter in beech, spruce, and mixed stands of beech and spruce show uniform patterns in all stands. Depth analysis of C and N describe continuing gradients without sharp boundaries, especially in transition of forest floor to mineral soil. On a chemical base no horizons could be divided. A delineation of forest floor and mineral soil seems to be possible only by analyzing the depth gradient of C but not by morphological criteria. Experiments in the same stands describing the humus stocks by standard methods based on morphological criteria show divergent results from analytical results. Pure beech stands show lower humus stocks compared to spruce stands, especially in the oldest age class. Spruce stands show a higher increase and a greater dynamic of accumulation of organic material on the forest floor. Mixed stands of beech and spruce show similar results compared to spruce stands than to beech stands. Linear regression models could be derived between the height of forest floor and element stocks. Therefore height of humus stocks is a good predictor of C, N, P, and S stocks in the forest floor, but only if the boundary between forest floor and mineral soils is defined by analytical measurements. Experiments to predict organic dry mass based on morphological delineation failed. We concluded that a distinct description of soil organic between forest floor and mineral soil based on field methods may be faulty, because there is continuing transition of C-content, which is only measurable by analytical methods..