Determination of humus quality using Rogister method along the elevation gradient in beech forests (Fagus orientalis Lipsky) (Case Study: Districts 1 and 5 of Kelardasht forests)

The aim of this study was to determine the humus quality using Rogister method along an elevation gradient in beech forests. For this purpose, first, along a transect (north-south) in the forests ofdistricts one and five of Kelardasht forest, 30 releves in tree and shrub layers and 30 releves in herb layer were sampled with dimensions of 20m × 20m and 10m × 10m, respectively. Then, the amount of vegetation was estimated using modified Braun-Blanquet scores. The A-horizon was sampled up to a maximum of 10 cm and its available moisture, pH and nitrogen was measured. After extracting ecological indicators’ values from three different sources and calibration values with measured data, classification of vegetation was performed using TWINSPAN and finally, the humus quality for ecological groups was determined using suggested ecogram by Rogister. The results showed that humus type at low, middle and high elevations is active mull, typical mull and acid mull, respectively. In other words, the humus quality decreases with increasing elevation. In addition, it was found that humus type for beech is acid mull. It is concluded that plant species (herb layer) can be a useful indicator for determining the humus quality of a forest ecosystem. In other words, after calibration of the main ecological indicators’ values, Rogister method can be used for sites classification in beech forests of Iran.