Species-abundance models as an indicator of disturbance in west oak woodland (Quercus brantii Lind.) of Iran

Changing environmental conditions, reactions of biotic factors and invasion of invasive species due to anthropogenic or natural disturbances, will change composition and diversity of plant communities over time. Therefore, the measurement of species diversity can be useful in the analysis of disturbance and ecosystem management. Effects of disturbance regimes including "grazing", "fire" and "no disturbance" in Daalaab Park were studied on oak communities. Information of vegetation, soil and other environmental variables were collected from 77 sample plots (256 m2) using the random sampling method in various disturbances classes. Species-abundance models were applied to assess diversity. Results of canonical correspondence analysis showed that "Grazing" and "fire" with the soil and topographic factors were identified as the most influential factors on plant composition. The results of species distribution models were showed that grazing disturbance class was fitted with the geometric model. A trend of this model to the Lognormal was observed. This result supported this assumption that communities affected by disturbance, have a change from a state with less destruction to the status with high destruction that most severely affected by natural and human disturbances. Matching of fire disturbance class with log series, was represented the immaturity of these communities that due to the onset of secondary succession in this class, it is logical and consistent this theory. If that, without disturbance class was matched with the log normal model. This model reflects the mature communities with high richness and diversity.