Comparison of Leaf and Soil Nutrients in Natural and Afforested Persian oak

Afforestation with oak (Quercus brantii Lindl) trees has been done for restoration of degraded areas in Zagros forests, however, few studies have been done on the dynamics of leaf and soil nutrients compared to natural trees (standard and coppice). The aim of this research is to compare the nutritional elements of leaves in natural trees (standard and coppice) and planted forms of persian oak (with an average age of about 30 years).

According to the objectives of the research, in the city of Ilam, where afforestation with persian oak species was carried out in the vicinity of its natural form, sampling were done from leaves and the soil (at a depth of 0-20 cm) in the two seasons of spring (April) and summer (September) to compare the changes in carbon, nitrogen, phosphorus, potassium, calcium and magnesium and some physical and chemical characteristics of the soil. Two-way analysis of variance (GLM) used to compare the soil and leaf properties among different regions. Principal component analysis (PCA) and Pearson's correlation test were used in order to investigate the relationships between leaf and soil nutrients and their changes in different forms.

results of GLM showed that nitrogen and phosphorus of leaves were affected by different forms of oak species and season, and their amount is higher in spring than in summer. So that the amount of nitrogen in the leaves of standard (20.2% to 1.68%) and planted trees (1.78% to 1.25%) was higher in spring compared to summer. The amount of calcium in the leaves in summer was between 1.5 and 2 times higher than in spring (planted oak; 303.66 ppm to 170.33 ppm, coppice; 282.33 ppm to 149.33 ppm, standard tress, 285.66 to 233 mg/kg. Leaf potassium was influenced by different oak forms and seasons. So that it was more in spring than in summer and in standard (201.16 mg/kg) and planted trees (161.47 mg/kg) it was 1 to 1.5 times than that of coppice trees (128.30 mg/kg). Principal component analysis and Pearson correlation showed that in two seasons, different forms of oak can be separated from each other.

Therefore, it can be said that the planted Persian oak trees are similar to the standard form in terms of nitrogen, potassium, and phosphorus elements and were more than coppice trees. In addition, in planted, unlike natural forms, the amount of leaf elements were higher in summer than in spring.