The aim of this study was to recognize plant communities of Box tree (Buxus hyrcana Pojark.) stands in the Khybus protected area, located in the middle part of Hyrcanian forests (north of Iran). Vegetation releves, 64 numbers, were made at peak vegetation cover during last summer by systematic-selective method in 200 and 400 meter grid dimensions by consideration indicator stands concept. By using Braun-Blanquet tabular method, six distinct plant communities including three associations: Rusco hyrcani-Fagetum orientalis, Buxus Hyrcani-Fagetum orientalis and Tilia sp.-Buxetum hyrcana with three subasociations: Rusco hyrcani- Fagetum orientalis Lauroceraetosum officinalis, Buxus Hyrcani-Fagetum orientalis parrotioetosum persica and Buxus Hyrcani-Fagetum orientalis aceretosum velutinum were determined. By using two way indicator species analysis, TWINSPAN, six plant communities were recognized. Braun-Blanquet tabular method and TWINSPAN fitness were estimated as 98.4% based on similar membership of relves in each plant community. Moreover, plant communities based on two first DCA axes, which represent 33% of total variances in whole of floristic data, revealed that each plant community had its own range and rather clear bordeline. Totally, results of this study not only describe plant communities of Khybus protected area as a climax model of Hyrcanian mountainous forests for the first time but also confirm that subjective Braun-Blanquet method, despite the development of numerical methods in multivariate classification of vegetation, can be used as an efficient method of separation and classification of forest sites.

The composition of real floristic associations is as the result of the influence of environmental factors and in potential reaction of plant with their ecological ability. The vegetation of the area was studied by Braun-Blanquet method. The study of region is in 40 kilometers north of Gorgan in 37o14’4” N and 54o29’8” E longitude and 10 meters altitude from the sea level. 4 releves omitted, because they were mostly like the other releves and 64 releves remained and 27 species analysed. Phytisociological data analyzed with factorial correspondante analysis (FCA) and the hierarchical ascendant corresponding (HCA) method. Finally 11 associations were distinguished in the area. These associations are as follow1. Aveno ludoviciana - Aeluropodetum lagopoidis2. Aeluropodo lagopoidis - Artemisietum sieberi3. Puccinellietum distantis4. Plantaginetum coronoputae5. Salicornio europaeae - Halocnemetum strobilacei6. Frankenietum hirsutae7. Frankenietum pulverulentae8. Salsolo turcomanicae - Halocnemetum strobilacei9. Polypogono monspeliensis - Halocnemetum strobilacei10. Halocnemetum strobilacei11. Zingerio trichopodae - Halocnemetum strobilaceithe distribution of the plant association in the intchebroon was mainly affected by salinity moisture and texture of soil.

Arasbaran Biosphere Reserve is the ninth Biosphere Reserve in Iran with a total area of 78759 hectares in northwest of Iran. Most of it is forest, pasture and agricultural lands. The difference between the height of 265 m and 2868 m above sea level, the presence of physiographic, soil and microclimates have created different habitats that have made its unique flora richness. Vegetation of lowlands of this area was carried out using Braun-Blanqet method. Data analysis (releves and plant species) was performed based on the Corrospondence factorial analysis (AFC) method in anaphyto software. In the lowlands of the Arasbaran Biosphere Reserve, Five associations and four subassociations including 176 taxa have been identified, of which 7. 9% are phanerophytes, 8. 5% chamaephytes, 25% hemicryptophytes, 4. 5% geophytes and 54% terophytes. Considering the global importance of this Biosphere Reserve for flora, vegetation and fauna, its further conservation is recommended as a natural heritage for the future.

Bagheshad region a part of Khojair national park with 2310 hectares area, is located in 22 Km far from east of Tehran in south of Haraz road. Vegetation of this area was studied based on Braun-Blanquet method. Phytosociological data was analyzed by AFC and CAR methods using Anaphyto software. In this area 9 plant associations and 6 plant sub-associations have been distinguished. Ecological characteristics showed that distribution of plant associations is dependent on altitude, slope, soil depth and texture. Other ecological factors such as pH, calcareous, N, P, K and organic matter contents have less importance in distribution and habitat of plant associations.

The weed PHYTOSOCIOLOGY in Damghan fields, have been studied using the method of Braun- Blanquet.198 releves have been taken from 28 fields and 19 releves have been deleted due to fimilarity with the others, and phytosociological data analysis on 149. Remained releves were been done according to the C.A.H (Classification Ascendante Hierarchique) and A.F.C. (Analyse Factorielle des Correspondance) methodes.22 associations and subassociations have been defined. Weeds are mainly therophyte (47/5%) and hemicryptophyte (32/8%). Geophytes are less frequent (9/83%).Cosmopolitan elements are 39/3%, Irano-Turanian 22/9% and the rest are pluriregional.

The genus Carpinus is considered as a common taxon in the temperate forests of the northern hemisphere, of which three species (Carpinus betulus, C. orientalis and C. × schuschaensis) were reported from the Hyrcanian forests of Iran. These are the main species of a number of Hyrcanian plant associations and usually appear with a high frequency. In this research, vegetation and the environmental conditions of C. betulus and C. × schuschaensis habitats were studied at the protected areas of Naghibdeh and Mazdeh forests. Data was collected using 46 relevé s. Data collection and analysis were performed according to the Braun-Blanquet method. TWINSPAN was used to classify and analyze the vegetation data, and CCA ordination was used for the species-environment analysis. Based on the results, the vegetation was classified into four groups belonging to two associations: Querco castaneifoliae-Carpinetum betuli Djazirei 1964 and Zelkovo carpinifoliae-Carpinetum schuschaensis ass. nov. in which the characteristic species of the new association were C. × schuschaensis, Z. carpinifolia and Pyrus boissieriana. The topographic and soil texture variables were significantly different between the two communities. The first association was distributed on fairly low-gradient slopes (41% in average) with southwest aspect and in the soils with a higher percentage of silt, whereas the second one was established on steeper slopes (74% in average) with southeastern aspect and in the soils with more sand. The canopy percentage of the second association was significantly higher than that of the first one. These two associations are placed in the Parrotio-Carpinion Djazirei 1964.

Understanding laws of growth and development, the interaction between structures and natural factors, and evaluating potentials of ecosystems is the first step is providing a well-founded management to meet economic and social needs and help natural ecosystems to preserve their dynamism. Site classification, with respect to ecologic factors, can act as a criterion to assess the quality of forest ecosystems. This research is aimed at classifying sites based on plant associations, and has been carried out in the educational-research forest of the University of Tehran located in Kheiroudkenar, Noshahr. The Braun-Blanquet method was used to study the plant associations. The data on plant associations were analyzed by the ANAPHYTO software product. The associations existing in the region were determined. The associations were classified according to the species arranged in the PHYTOSOCIOLOGY table. Results of the research show that two plant associations may be recognized in this region, while each includes a subassociation:1. Rusco-Fagetum and its subassociation Mercurialietosum perenni and its distinguished species….2. Carpinerto-Fagetum and its subassociation Epimedietosum pinnatii and its species named …..

The northern forests of Iran are Tertiary relicts and large parts of its lowlands have been destroyed due to human interference. However, only some small patches of these forests have remained yet which deserve a high value of conservation policies. Noor and Sisangan forests in Mazandaran lowlands were investigated with a phytosociological approach. The phytosociological data were collected from 55 relevés and classified using modified TWINSPAN in the JUICE software. Four vegetation unites were described: Celtis australis-Buxus hyrcana, Fraxinus excelsior subsp. coriariifolia-Cardamine tenera, Populus caspica-Alnus subcordata and Parrotia persica-Carpinus betulus. Exhaustive investigation of all diagnostic species of described communities in the Hyrcanian forest, clarified the connectivity of the studied vegetation unites with two major alliances, Parrotio-Carpinion and Alnion subcordatae. Obviously, the final decision on the syntaxonomical situation of the associations would be impossible without more a comprehensive investigation on the whole Hyrcanian area.

In this study the vegetation of gherh Aghaj in Pakdasht with the longitude of 51- 45 to 51- 57 and the latitude of 35-25 to 35-35 located on the south west survyed relation to the physionomy of vegetation. Sampling was conducted in releves. The study area separated in to plant unit using areal photographs. Broun- Blandqve table method was used for each plant unit, with regards tomp scale, twenty seven plant communities were Recognizes region. The physionomic studies were made according to kuchelers and one physiognomic formula was made to each plant community.