Abstract:
To investigate the movement of elements (N, P, k, Ca, and Mg) from the tree crowns by natural litterfall and leave wash, plots were established on six 450 year-old growth stands at the H. J. Andrews Experimental Forest. The following are the results of the data analyses. Elemental concentrations contained in throughfall samples varied throughout the year and tended to follow a seasonal cycle. Concentrations were lowest during the winter when precipitation was greatest and highest during the summer months when precipitation was lowest. Nutrient return in throughfall generally followed the same trend as did the concentration curves. The general mobility of the various mineral elements was demonstrated. For example 12% of the N, 39% of the P, 74% of the K, 9% of the Ca, and 37% of the Mg was returned in the leaf and litter wash. Average litter production for all stands during the 2 years was 5.520 metric tons/hectare. Litterfall was maximum during the winter months. The average total kg/hectare return of nutrients in litterfall was N 26.7, P 4.6, K 75., Ca 49.9, and Mg 3.8. The greatest portion,
63% of the nutrient return, came through needle litterfall. Together, the needle, cone, and twig litterfall accounted for 84% of the total nutrient input through litterfall.
