¹Department of Biology, Faculty of Science, University of Guilan, Rasht,Iran ²Department of Biology, Faculty of Science, University of Mazandaran, Babolsar, Iran Abstract Palangan habitat of protected area Aghdagh is located 10 km south of the city of khalkhal in ardabil province. This habitat area is 17,568 hectares. Altitude is m.Plant species of habitat in the years 1388 and 1389 were collected and identified. And their life form and geographical distribution with determination of the percentage effect of environmental factors (altitude and slope habitat) on vegetation and environmental characteristics in determining the most important settlement was done. About 362 species were identified belonging to 220 genera and 57 families. Floristic diversity, flora and environmental characteristics of this area using a transect along altitudinal gradients using TWINSPAN, DCA analysis and Pearson coefficients were evaluated. According to this analysis, the altitude and slope of the main factors affecting vegetation zone area. Introduction Iran has a total surface area of 1.65 million km². Species Diversity that is a combination of richness and evenness, largely in studies of vegetation and environmental assessment as one of the important indicators in determining the status of ecosystems is used. With geographic coordinates is 37°23' 19" latitude north and48°40'39“ east longitude. Minimum and maximum height is 1300 m to 2800 meters above sea level, respectively. The average slope is percent. This habitat area is 17,568 hectares. Average annual rainfall mm in the range of studies and relative humidity is 65 percent annually. Minimum annual mean temperature approximately 2 ° C and the maximum annual mean temperature is 14 ° C. Methods Results The results of the samples shows that the number of 362 species belonging to 220 genera and 57 families of vascular plants present that among them, dicotyledons with 47 species richest group are monocotyledons with 8 and gymnosperms wih two species are present. Among this families, (Asteraceae) with 64 species, (Brassicaceae) with 35 species, (Lamiaceae) with 33 species, (Fabaceae) with 27 species, (Rosaceae) with 17 species, (Apiaceae) with 15 species. Classified according to the life form showed that 54% Hemicryptophytes and then the order is Triophytes (25%), Geophytes (10%), Phanerophytes (6%) and is Chameophytes(5%). Belong to the areas of phytogeographical (chorotype) to the largest elements Irano- Turanian and then Euro - Siberia / Irano- Turanian are present. Endmism are 4.2% among the 362 species (15 species). The medicinal species are the most important factor in removing is the sample during the first axis Height (Altitude) 16% of the total species. in CCA Analysis, and during the second axis vector slope (Slope). Based on analysis Twinspan, four groups were identified plant. Discussion Palangan habitat flora Representing biodiversity of plants and favorable living conditions in the study area because it can be in ¬ Geographical area and topographical conditions that sought non- uniform. Considering the amount of high mountainous areas Endemism (Zohary, 1973), because 15 species exclusively in the area stop creating due to continuous grazing species. Overall, altitude One of the limiting factors of plant development. Number of species and species richness decreases with height similar to a study in which the number of mountain flora species and species richness decreases with increasing altitude (Brown & Gibson, 1983 (. Also species richness with increasing precipitation at high altitudes to reduce the temperature shows a decrease (Petr pysek, 2002 ). Various studies of species richness decreased with increasing altitude suggests that our results are significant (Sagar et al. 2008) and (CM Sharma, 2009). For sampling, every 100 meters elevation (transect), the three plots were sampled. 45 Plots with dimensions 5 × 5 meters. All samples collected and dried to the scientific approach has been pressing using existing Flora especially Flora Iranica (Rechinger, ), Flora of Turkey (Davis, ) and Flora of Iran (Assadi et al., ) were identified and kept Herbarium of Guilan. life forms were used following Raunkiaer (Raunkiaer, 1934). Geographical distribution of particular flora Books Flora Iranica (Rechinger, ) has been extracted. Software Canoco 4.5 for ordination analysis was used (Ter Braak & Šmilauer, 2002). A non-limited ordination analysis DCA (Detrended Correspondence Analysis) and CCA. More TWINSPAN analysis software using Juice to show an overview covering the area was conducted. Differences in distribution and habitat variables between height Belts Anova using a method with the following differences between the sets with Post-hoc Tukey test are separated, have been analyzed. All tests of statistical software (spss, ν. 16) is done.