Effect of environmental factors on distribution of ecological groups in Paliurus spina- christi Mill. site (Case study: Marzan Abad, Chalous, Iran)

The Paliurus spina- christi species grow naturally in three different vegetation regions of Iran (Northern forests, Arsbaran and Zagros forests). But so far no research has been carried out on the sites of this species. Therefore, present study was conducted to investigate the effect of environmental factors on distribution of ecological groups in Paliurus spina- christi site in the Northern forests of Iran. To consider different condition of the study area, sampling was done based on land units and size of square-shaped plots was 400 m2 that it was determined by minimum area method. After recording existing data in each plot, soil samples were collected from the sampling plots. Then, vegetation data were classified by Two-Way Indicator Species Analysis (TWINPAN) using PCORD software and finally, Canonical Correspondence Analysis (CCA) were used to investigate the relation of each plant species and environmental factors, by CANOCO software. According to the results of TWINSPAN, there were four vegetation types in the study area. The results showed that different species, such as Pyrus cerasifera, Berberis vulgaris, Punica granatum, Cupressus arizonica and Carpinus betulus are indicators species of the study area, replace of Paliurus spina- christi. Also, the results of CCA showed that amount of C/N, N, saturated water content, bulk density, porosity, clay, phosphorus and soil potassium are effective factors on distribution of vegetation in Paliurus spina-christi site. On the other hand, C, organic matter, sand, silt, altitude, slope and aspect have not significant effect on plant ecological groups. According to results, the presence of Paliurus spina-christi is directly related to amount of N and bulk density. In this study, it was clearly shown that using CCA, it is possible to determine the relationship between each plant species and the most important environmental factors.