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Environmental gradients across wetland vegetation groups in the arid slopes of Western Alborz Mountains, N. Iran

100%

Kamrani A., Naqinezhad A., Jalili A., Attar F.

Acta Societatis Botanicorum Poloniae

2010

tom 79

nr 4

Mountain wetlands are unique ecosystems in the arid southern slopes of Alborz range, the second largest range in Iran. The spatial distribution characteristics of wetland vegetation in the arid region of the Alborz and the main factors affecting their distributional patterns were studied. A classification of vegetation and ecological characteristics were carried out using data extracted from 430 relevés in 90 wetland sites. The data were analyzed using Two Way Indicator Species Analysis (TWINSPAN) and detrended correspondence analysis (DCA). The wetland vegetation of Alborz Mountain was classified into four large groups. The first vegetation group was calcareous rich vegetation, mainly distributed in the river banks and characterized by helophytes such as Bolboschoenus affinis as indicator species. The second group was saline transitional vegetation, distributed in the ecotone areas and dominated by Phragmites australis. The third vegetation group is wet meadow vegetation which mainly consists of geophytes, endemic and Irano-Turanian species, distributed in the higher altitudes. This vegetation is mainly characterized by indicator species such as Carex orbicularis, high level concentration of Fe2+ and percentage of organic matter in the soil. The fourth vegetation group is aquatic vegetation, distributed in the lakeshores. The aquatic group species are mainly hydrophytic such as Batrachium trichophyllum. The TWINSPAN vegetation groups could be also recognized in the DCA graphs and ecologically differentiated by ANOVA of studied variables. Four vegetation groups can be differentiated on two first axes of indirect ordination. There is a gradient of pH, EC and organic matter associated with altitude on the DCA diagram. Correlation analysis between the axes of DCA and environmental factors shows that altitude, soil texture and other dependant environmental variables (e.g. pH) are the main environmental factors affecting the distribution of wetland vegetation groups.

Fire influence on the grassland vegetation in Golestian national park [Alborz Mts. Iran]

100%

Safaian N., Shokri M., Ahmadi M. Z., Atrakchali A., Tavili A.

Polish Journal of Ecology

2005

tom 53

nr 3

Frequent wild fires in mountainous grasslands of Alborz (Iran) influenced the sustainability of habitats and ecological niches of species in this ecosystem. In fact, fire has been a constant event in Golestan National Park in Alborz for a long time (67 fires during 1957 to 1997). Due to importance of this national park in northeastern Iran as a biosphere reserve, the research has been carried out in order to investigate the causes of the fires and the subsequent changes occurred in vegetation and habitat structure. Study was performed in two adjacent: burned and unburned areas in mountains of Alborz. The analysis showed that the vegetation coverage and the above ground biomass in the burned area were significantly greater in comparison to the control area. Whereas, the diversity of vegetation of the two areas did not show significant differences. It was also shown that the coverage of grass species like Stipa pennata L., Festuca valessiana, Avena wiestii Steud. and Aegilops tauschii Coss. increased with respect to the non-burned area. The coverage of woody species like Acanthophyllum pugens, Onobrychis cornuta (L.) Desv., Cotoneaster ovatus Pojark. and Rosa persica Michx. considerably decreased in burned area. Due to increase of annual species of grasses and decrease of woody species, it can be concluded that fire is a preventive factor in succession of ecosystem toward climax and the dominance of grasses can be regarded as a suitable condition for further fire occurrence.

Lower and Middle Jurassic ammonoids of the Shemshak Group in Alborz, Iran and their palaeobiogeographical and biostratigraphical importance

80%

Seyed-Amami K., Fursich F. T., Wilmsen M., Majidifard M. R., Shekarifard A.

Acta Palaeontologica Polonica

2008

tom 53

nr 2

The Shemshak Group at Shahmirzad (northern Iran) is characterized by the most frequent and extensive marine intercalations and contains the most abundant and diverse ammonite faunas hitherto known from the Lower and lower Middle Jurassic strata of the Alborz Range. So far, 62 ammonite taxa have been recorded from this area, including 25 taxa from earlier studies. The taxa belong to the families Cymbitidae, Echioceratidae, Amaltheidae, Dactylioceratidae, Hildoceratidae, Graphoceratidae, Hammatoceratidae, Erycitidae, and Stephanoceratidae with the new species Paradumortieria elmii and Pleydellia (P.?) ruttneri. The fauna represents the Late Sinemurian, Late Pliensbachian, Toarcian, Aalenian, and Early Bajocian. Palaeobiogeographically, it is closely related to the Northwest European (Subboreal) Province, and exhibits only minor relations with the Mediterranean (Tethyan) Province.

Ograniczanie wyników

1 Acta Palaeontologica Polonica

1 Acta Societatis Botanicorum Poloniae

1 Polish Journal of Ecology

1 Ahmadi M. Z.

1 Atrakchali A.

1 Attar F.

1 Fursich F. T.

1 Jalili A.

1 Kamrani A.

1 Majidifard M. R.

1 Naqinezhad A.

1 Safaian N.

1 Seyed-Amami K.

1 Shekarifard A.

1 Shokri M.

1 Tavili A.

1 Wilmsen M.

1 2010

1 2008

1 2005

Wyniki wyszukiwania

Environmental gradients across wetland vegetation groups in the arid slopes of Western Alborz Mountains, N. Iran

Fire influence on the grassland vegetation in Golestian national park [Alborz Mts. Iran]

Lower and Middle Jurassic ammonoids of the Shemshak Group in Alborz, Iran and their palaeobiogeographical and biostratigraphical importance