Quantitative evaluation of soil carbon and nitrogen dynamics under oak and alder ‎‎afforestations ‎

In recent years, with an alarming degradation rate of Caspian forests, afforestation can be considered as a suitable solution to restore the degraded areas. Different species especially Oak (Quercus castaneifolia C. A. M) and Alder (Alnus subcordata C. A. M) were planted in vast areas. Elements quantitative relations (stoichiometry) has an important roll in organic matter decomposition by changing these elements availablity in soil and is a main index to better undrestanding of microbial and OM conditions in soil as well. The aim of this study was to determine the effect of tree species in deferent ages on quantitative relations in these afforestations. This research was carried out in 15-, 20-, and 25-years old stands of Mazandaran wood and paper company afforestations and 30 soil and litter samples were collected from 10 cm depth of soils in each stand using systematic random method. Based on the results, the highest amount of quantitative relations of soil C/N (18.33), C/N microbial biomass (15.88), carbon to particle organic nitrogen ratio (10.36) and carbon to dissolved organic nitrogen ratio (3.00) were seen in older oak afforestations which had significant differences with alder afforestations. Also, oak stands in higher ages amend quantitative relations of soil carbon and nitrogen in future years of the afforestations, these findings provide a scientific theory for use in the evaluation of soil nutrients in afforested areas.