Effects of some topography and soil factors on vegetation structure in the northern profile of Oshtorankouh (Lorestan province)

In this research, the effects of some topography and soil factors influencing vegetation structure have been studied in Chal Kabud basin located in the northern slope of Oshtorankouh. It enjoys the greatest altitude variations, a rich diversity of plant species as well as topographical features. Nineteen altitudinal classes were identified by 100 m altitudinal interval. In each altitudinal class, 4 transects (2 vertical and 2 horizontal) each with 200 m length were established and 8 quadrates were sampled alongside each transect. In selected classes along the homogenous units, soil profile was dig and some edaphic parameters were measured. Vegetation characteristics and grazing intensity of all units also were studied. Fourteen vegetation classes were classified by TWINSPAN and plant species as well as sampling sites were analyzed and grouped by Dterended Correspondence Analysis (DCA) to 4 and 6 similar categories, respectively. In order to study the effects of environmental factors on vegetation, Canonical Correspondence Analysis (CCA) were applied and correlation among each environmental factor and plant species were measured. CCA results showed that edapic factors were the most effective factors on distribution and establishment of plant species in the study area and altitude, slope and grazing intensity were among the next important factors respectively.