The effects of altitude and the most important soil components on vegetation characteristics, Asalem watershed)

Abstract

This study aims at assessing the effect of altitude and the most important soil components on vegetation characteristics in the Asalem Watershed basin. For this purpose, 160 0.1 ha circular plots, were established along altitude gradient. Vegetation layers and soil physio-chemical characteristics were measured within sampling plot. The results of vegetation composition in different vegetation layers showed a fluctuation along the altitude gradients. Soil physical characteristics did not indicate specific variation pattern. Whereas, soil organic carbon was increased significantly along altitude (P≤ 0.01). The results of Canonical Correspondence Analysis (CCA) indicated a positive correlation between soil Ph and diameter at breast height (DBH) of Diospyros lotus, Parrotia persica, Quercus castaneifolia and Sorbus torminalis species. In shrub layer, there was a significant correlation between density of species and environmental factors. The density of Evonymus latifolia and Vaccinium arctostaphylos had a significant relationship with altitude, the percentage of phosphorus and silt, directly. In the herbaceous layer, significant relationship belonged to percentage over of Festuca drymeia, Lathyrus laxiflorus, Potentilla micrantha, Veronica persica and Viola odorata with altitude and percentage of organic carbon. According to the results, it can be noted that the altitude is the main factor in the distribution pattern of vegetation composition in the study area. Changes in environmental conditions along the gradient, are effective on the quality and quantity of soil organic matter through vegetation changes which provide favorable conditions for the establishment of a specific plant species

Keywords

• forest ecosystem
• environmental factors
• physical and chemical soil properties
• west of guilan