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

Asghar Kamrani,Alireza Naqinezhad,Farideh Attar,Adel Jalili

doi:10.5586/asbp.2010.037

Abstract

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.

Highlights

Studies focusing on wetlands of Alborz Montains, the second largest in Iran are parts of on-going ecological research on dry mountain wetlands of Iran
Major gradients in the wetland vegetations The mountain wetland habitats of Alborz show a great range of vegetation variation
Four groups have been recognized at the three levels of TWINSPAN divisions (A, B, C and D)

Summary

Introduction

Studies focusing on wetlands of Alborz Montains, the second largest in Iran are parts of on-going ecological research on dry mountain wetlands of Iran. The Mountain wetlands of the southern slopes of Western section of Alborz are from environmental view point sharply differentiated from the adjacent arid steppe ecosystems. Despite their relatively small and scattered area, they are extremely important contributors to plant species diversity within Irano-Turanian phytogeographical region (sensu Zohary 1973). VEGETATION ECOLOGY OF WETLANDS OF ALBORZ gical factors have been the subject of many ecological studies in recent years (Hájková et al 2006; Pinto et al 2006; Rolon and Maltchik 2006; Hájek et al 2008; Hájek et al 2009; Victoria 2009) Most of the latter studies are related to wetland vegetation especially ones of mountain ecosystems (Gerdol and Tomaselli 1993)

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Discussion

Conclusion