The effects of seasonal changes on some chemical forest soil properties during one year (Case study: Marivan forests)

Soil is one of the important components of the forest ecosystem and getting knowledge about the chemical properties of soil can be a good guide for analyzing of forest ecosystem health. In this research, soil samples were taken during a year over four times at intervals of three months (March, June, September and December) in order to evaluate the effect of seasonal changes on chemical properties of topsoil in Marivan forests. Five composite soil samples in each season were collected and altogether 20 samples were taken. Soil organic carbon, nitrogen, phosphorus, pH, electrical conductivity, potassium, calcium and magnesium were analyzed in the Lab. Data analysis was conducted using one-way ANOVA and Duncan's multiple range tests. The result of this study showed that the maximum amount of organic carbon, total nitrogen and phosphorous were observed in the summer that was 10.7%, 0.59% and 44.7 ppm, respectively while the least amount were observed in the winter which was 8.01%, 0.2% and 39.05 ppm, respectively. There were no significant differences in organic carbon and phosphorus during year and over seasons, but total soil nitrogen showed statistically significant (p < 01) differences over time. Also pH (p < 0.01), EC (p < 0.05), Ca (p < 0.05) and Mg (p < 0.01) showed statistically significant differences over time while changes in the amount of potassium were very low and showed no statistically significant differences over a year