American-Eurasian J. Agric. & Environ. Sci., 7 (4): 406-414, 2010 ISSN 1818-6769 © IDOSI Publications, 2010 Corresponding Author: Mansour Jahantigh, Research Center for Agriculture and Natural Resources of Sistan Iran 406 Effect of Wastewater Irrigation on Phytosociological Characteristics of the Vegetation: A Case Study in Sistan Region by Mansour Jahantigh and Recep Efe 1 2 Research Center for Agriculture and Natural Resources of Sistan Iran 1 Department of Geography, University of Balikesir, Turkey 2 Abstract: The aim of this study is to determine the changes in plant diversity and phytosociological attributes of the vegetation according to the environmental conditions in Sistan Region in the southeast of Iran. For the study of plant communities and quantification of vegetation, quadrate method was used. Quantitative analyses on species diversity in addition to phytosociological attributes analysis were conducted in dry land, agricultural and waste water irrigation area. Data on abundance, density, dominance, frequency, Species Importance Value Indexes, are presented in the study. The plant communities were determined in percentage of frequency, abundance value, relative density and importance value. Based on results of survey that performed in study area, 16 species from 7 botanical families were recorded in all sites. The phytosociological studies reveal in most part of area that the vegetation was characteristically dominated by Tamarix species followed by Aeluropus sp. and Alhagi maurorum, which were the most abundant and frequent species of the study area. The Tamarix species has the highest IVI, in all surveyed areas. Species presenting the highest relative density is Aeluropus littoralis in the agricultural and wastewater area and Aeluropus littoralis in dry land area. It was observed that, wastewater plays an important role in vegetation growth and regeneration. The experiments from wastewater irrigated sites reported maximum number of species, depicting highest diversity among all sites. This clearly indicates that the wastewater can be effectively used in restoration of dry land, since it helps better growth of plants. Key words: Vegetation Dry land Agriculture Wastewater irrigation Phytosociology INTRODUCTION wastewater may increase the risk of groundwater Arid regions occupy 36% of the earth land surface however, by appropriately matching plant production and water shortage is the main limiting factor in the systems to effluent characteristics [11]. In order to avoid development of dry lands. Soil degradation, erosion, undesirable side effects due to salinity and toxic salinization, sodication are main issues and water and soil concentrations of metals from the application of management is very important if the dry lands are to be wastewater to soil, it is necessary to determine the habitable. Vegetation is an essential component in major effects of wastewater concentration in long-term periods ecosystems because it displays the effects of various [12-14]. Ecological research on the relationship between environmental conditions [1-3]. Phytosociological studies biodiversity and environmental conditions has been reveal the structure and diversity about the vegetation increasingly emphasized. But, the importance of waste [4-7]. Plant cover protects soil from the erosive action of water irrigation has been understood better after severe runoff water by contributing resistance to the movement drought conditions in arid regions. of water and shielding the soil from its effects. The use of The Sistan region of southeastern Iran has not only wastewater for irrigation is increasingly being considered suffered significant destruction of plant life as a result of as a technical solution to minimize soil degradation and to the droughts of recent years, but erosion caused by wind restore the vegetation in dry lands. has also increased. Since natural water sources are limited, Wastewater irrigation poses several threats to the efforts are being made to revitalize the vegetation cover environment via contamination by nutrients, heavy using waste water. Helmand River and Hamoon lakes are metals, and salts. Increased loads of nitrates in ecologically very valuable and important wetlands in contamination [8-10]. The risks can be markedly reduced,