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Boujagh National Park, with water ecosystems including Boujagh and Kiashahr wetlands, has an area of approximately 3477.3 hectares. In order to study factors affecting the vegetation in aquatic and wet habitats, 44 releves were implemented in the region. To test the chemical properties of the available water, samples were collected from 22 releves. The results of a two-way species indicator analysis of the modified TWINSPAN suggested that four groups of plants were present in the region. The first group being floating, immersed and submerged and the third and fourth groups being mostly helophytic. The second group of plants grows in areas with sand and mud. The results of comparative DCA analysis of water factors (PH, Depth, P, N, Cl, CO₃, Hco₃, EC, Na, K) showed a significant correlation between the factors and plant groups and the most important factors influencing the distribution and separation of plants was found to be water depth. In addition, Boujagh and Kiashahr wetlands vegetation map, based on the plant groups, was also prepared.

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This paper concerns itself with the study of sand beaches of the Boujagh National Park with an area of 3477 ha. The purposes of this study include the determination of the plant species diversity and plant groups. In ad-dition, the determination of the impact of environmental and specific variables on the presence or absence of certain species and their communities is another aim that the study follows. In order to attain those purposes, 52 plots across 6 transects of the district were used. In each plot, the materials were identified and abundance-dominance of species by using Braun-Blanquet criteria were obtained and their life forms were determined according to Raunkiaer clas-sification. To determine the plant groups, a Two-way analysis of significant modified species (Modified TWINSP-AN) was utilized. Detrended Canonical Analysis (DCA) was used to determine factors affecting plant groups. The results showed that four plant groups exist in this district: Convolvulus persicus-Crepis foetida subsp. Foetida grou-p, Argusia sibirica group, Eryngium caucasicum-Juncus acutus group and Rubus sanctus group. The first and seco-nd groups consist of higher percentages of therophytes and spread in areas where the soil contains more sand. Plants in the third and fourth groups spread in areas with stabilized sand and high percentage of silt. DCA analysis results showed that soil factors (texture, OC, Na, K, N, Ca, Mg) have significant relation with plant groups were studied. Among the plant groups, the percentage of silt and sand, species richness and life forms of therophytes and geop-hytes show significant relations. Therefore it can be concluded that these factors affect on the separation and distri-bution of plant groups.

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Fire affects vegetation and changes plant succession. In this paper, the vegetation of Sirachal Research Station, which burned in the summer of 2014, was studied and compared with the unburnt areas, based on biodiversity indices. The research was implemented as a factorial experiment in a completely randomized design. First, on the basis of physiognomy, the area was divided into three parts: shrubland, shrubland-rangeland, and rangeland. Each part was, then, divided into two sections, including a burnt area and an adjacent unburnt area (control area). In each area (burnt and unburnt), three sampling units were randomly assigned using PNP method, and vegetation measurements were subsequently performed. Based on data analysis, a total of 141 taxa were identified, belonging to 28 families and 95 genera, including one species of Gymnosperm, 19 monocotyledons and 121 dicotyledons in two burnt and unburnt areas of Sirachal Station. Based on the statistical analysis, using Past3 and SPSS softwares, there was no significant difference in the number of taxa between the vegetation of the burnt and unburnt areas. Of the indicators analyzed in Past3, the number of individual, the index of Menhinick's richness and the Shannon diversity index were significantly different in the treatments sampled from the burnt and unburnt areas. According to the Duncan test average, the number of individuals in the unburnt area, with a canopy cover below 25%, was greater than that in the burnt area, with the same canopy cover, however, no significant difference was observed between the individuals in the burnt area and unburnt area, with the same canopy cover of more than 25%. Also, the richness of the burnt area with a canopy of less than 5% is significantly higher than that in the unburnt area with the same canopy cover.