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The dynamics of nutrients and their return to the soil through the litter is one of the most important pathways of the nutrient cycle in forest ecosystems. The aim of this study was to evaluate the dynamics of nutrients in pure beech, pure hornbeam and beech-hornbeam stands in Darabkola educational-research forest of Sari. For this purpose, in each stand, 10 sample plots with 1000m2 area were randomly established and by measuring the diameter and height of the trees, descriptive statistics of the studied stands were calculated. Then, litter traps with dimensions of 50 × 50 cm to measure the amount of litter fall per unit area and litter bags with dimensions of 20 × 20 cm (with a pore of 2 mm) with 10 replicated were installed in the studied stands for 360 days and at intervals of 60, 120, 180, 240, 300 and 360 days, the concentrations of nitrogen, carbon, phosphorus and potassium in the litter of the bags were measured. According to the results, the highest rate of litter falls with 1817 kg/ha was related to November and December in beech stands. In addition, the highest input of the studied elements was related to the pure hornbeam stand. The resultas also indicatedthe dynamics of phosphorus, potassium and carbon elements in pure and mixed stands are decreasing with a slight increase at the end of the period and increasing in the case of nitrogen and decreasing at the end of the period. The dynamics of the elements in the mixed stand showed more fluctuation than the pure stands. Also, the results of this study showed that the 200th to 300th days after litter fall is an important time range in the fundamental changes in the dynamics of litter nutrients.

The aim of this study was investigation of Carbon, Nitrogen and Phosphorus dynamics in Carpinus betulus L. leaf litter in organic layer of a broad-leaved mixed forest in Gorgan. Fresh litters were collected from five plots in district one, Shastkalate forest and were placed into some litterbags with 2 mm mesh. Then, they were located in the study site. Over one year (8 sampling), chemical analysis was carried out. Result showed total Nitrogen concentration in fresh litters was 1.5% and after one year increased to 1.9%. Phosphorus concentration in fresh litter was 0.134% and increased to 0.136% after one year. Carbon to Nitrogen ratio in fresh litter was 24.5, but after one year decreased to 17.4. Carbon to Phosphorus ratio in fresh litter was 282 and after one year decreased to 245. Weight of fresh litter was 14.65gr, but decreased to 8.23gr after one year. Nitrogen content, C/N and N/P ratios of Hornbeam leaf litters were correlated with secondary weight of litter. C/N and C/P ratios were appropriated for discriminating of decomposition phases. Hornbeam Leaf litters caused soil fertility and increased site indexes. It is necessary to use Carpinus in reforestation and rehabilitation of destroyed forest, considering climate, elevation and forest degradation density.