حامد جنیدی جعفری

Programs on sustainable development of natural resources especially on rangelands are becoming more important. However, such programs need reliable information on various factors affecting those resources. This research has been taken place with the aim of explaining the environmental and managerial factors influencing the vegetation distribution on Saral rangelands, the Kurdistan province, western Iran. The study area was forbland, grazed mostly by sheep (animal) and the seasonal use was concentrated in summer. Plant types were recognised; the existing flora was determined and some plant parameters were then measured (number of plants, cover percentage, absence and none absence, plants frequency and dominancy) in the study area. The environmental factors such as topographic factors (slope, slope direction, and elevation), soil physical factors (soil depth, soil texture, stone and gravel) and various chemical factors such as acidity, electrical conductivity, lime, gypsum percentage, organic material, nitrogen, phosphor, calcium and potassium) were measured. For investigating effect of grazing factors on plant distribution as management index, the study’s area condition was determined. The Principal Component Analysis (PCA) was used to determine the relationships between vegetation cover and environmental factors. the results showed that among various environmental and managerial factors affecting plant distribution on rangelands, soil depth, grazing intensity, elevation, sand, gravel and silt percentage have the highest correlation with PCA. It was further shown that soil physical properties have greater impact on the distribution of plant communities than soil chemical properties. Physiographic factors including elevation and managerial factors including grazing intensity have considerable effect on the distribution of plant communities. Keywords: