جستجوی مقالات مرتبط با کلیدواژه « شاخص های تنوع » در نشریات گروه « محیط زیست »

Amir-Kelayeh international wetland is as one of the important wintering habitats for birds. In present study, the density and diversity of bird species (waterbird, wader and terrestrial bird dependent to the wetland) has been studied in Amir-Kelayeh international wetland based on the semi-winter birds census data, over a 10-year statistical period. During this ten-year period, the total number of 334776 birds from 46 different birds species was recorded in this wetland. Among the studied years, the highest number of 72188 birds in 2008 and the lowest number of 1877 birds in 2015 have been counted. In terms of quality and food items, this wetland and it's around paddy fields is a good refuge for the Anatidae and Rallidae family that with 64.86 and 50.06 percent of frequency depending on their diet, have the most abundant among the identified family. The biodiversity indexes showed a relatively high amounts, but with a declining trend, and also the index of species evenness indicated a stable trend during this 10-year period in Amir-Kelayeh Wetland. Considering the decreasing trend of biodiversity indexes in Amir-Kelayeh wetland in recent years, increasing the wetland ecological conservation through the management plans such as habitat structure conservation, and illegal hunting and pollution control is recommended.

The intertidal coral reefs are influenced by a composition of environmental parameters and biological components, which has a direct influence on communities associated with them. Hence, this study investigates the effects of some environmental parameters such as sea water factors and substrate compositions on distribution pattern of macrobenthos associated with the order Zoantharia on intertidal zone of Hormuz Island using diversity index variables and abundances data sets obtained over a period of 12 months between June 2015 and June 2016. For this purpose, line intercept transect method was performed to assess the abundances of zoanthid polyps and associated macrobenthos along 6 transects with 3 hard bottom types. The results of this study revealed significant differences in species evenness and species richness between T3 and T6 with other transects. The diversity indices of macrobenthos, tested with Bray-Curtis similarity index, was significantly homogeneous in all transects with the exception of T3 and T6, probably as a consequence of different substrate compositions in habitat heterogeneity. Pearson analysis results showed positive significant correlation among macrobenthos abundance and dissolved oxygen in all transects, so that the analysis of multiple linear regression showed this significant relationship in upper littoral zone of transects. In conclusion, substrate composition was the main factor limiting the spatial distributions of macrobenthos associated with zoanthids, although dissolved oxygen was also important. Also, the abundances data showed two distinct benthic communities and support the hypothesis that the distribution pattern of communities varies along the coastal area in a gradient from the upper to the lower portion of the intertidal zone.

Protection and developing of biodiversity are the most important subjects in forest management. The aim of this study was classification of ecological groups in Vezg forest of Yasouj and evaluation of biodiversity indicators in ecological groups. For this purpose، 52 sample plots 450 m2 were measured with systematically random method for collecting of vegetation. The TWINSPAN method and Canonical Correspondence Analysis (CCA) were used for the definition of ecological species groups and determining the relationship between ecological species groups and biodiversity indices. Also، plant biodiversity were studied based on species abundance data with general biodiversity indices. Also Tukey test and Pearson correlation analysis were used for finding significant differences between the ecological groups، alsodiscriminate analysis was used for determining of significant biodiversity indices and separate of ecological groups. Results showed that، there were four ecological species groups in the study area. The First group including: Anchusa italic-Quercusbrantii، the second group: Heterantheliumpiliferum-Avenaclauda، the third group: Teucriumpolium and the fourth group: Salvia reautreana. The ecological groups were significantly different in terms of all diversity، richness and evenness indices، so that were greater in the third and fourth ecological groups that were in high elevation and north slopes. The second and third ecological groups showedthe highest and lowest beta diversity respectively. Therophytes had the highest life forms spectrum in all of ecological groups and in geographical distribution، the forth group had the highest Irano-Turanian and Cosmopolite species. Results showed that، Shanonweaner diversity and Menhenik richness indicators، were the most important effective factors in separations of ecological groups.

Sanaye Foolad wetland is one of the largest and most important semi-artificial wetlands in Khuzestan province that in terms of habitat of fish, water birds and waders is too valuable and according to the importance and special ecological values of water birds in wetland fields, awareness of changes related to the population of different species of birds, has basic role in management of these kind of areas. Therefore, the present study is done to identify and compare the density and diversity of water birds and waders come out in the second half of 2008.In this research, birds were counted monthly from October to March 2008 and according to "total count" method which is the recommended method of WI. In this wetland 13 species of water birds and waders from 7 families were identified during 6 month period of the research. Results that are achieved from frequency of bird families in Dalov tynas wetland shows that in fall, Rallidae (33.98%) and in winter Recurvirostridae (36.78%) have had the maximum frequency. In the other hand, results obtained using biodiversity index shows that October in terms of Shanon-Winer &S impson diversity (2.657, 0.829), October and November in terms of Menhinx & margalf species richness (1.604, 0.527) and February in terms of Karmago and Simpson evenness index (0.892, 0.0817) possess the most biodiversity of water birds and waders during the research period.

Shadegan Wetland as a permanent Salty, Brackish and Freshwater is highly important for protection of resident and migratory bird,s species.This wetland acts as drinking water supply reservoir, breeding habitat, feeding ground for the resident and migratory birds.This wetland provide a refuge and temporary resting site for passage migratory birds.Identification of the waterfowl species of this wetland began on 15th August 2000 and ended on 15th December 2001 in the seven stations.9 families with 26 species of waterfowl were identified.Laridae had the highest No. species (the most diverse)with 11 identified and Phalacrocoracidae the last No. of species with 1 identified.Winter season 2000, had the highest No.(46%) and Shannon diversity (=2/41) of waterfowl species and Autumn 2001 had the least No.(3%) and Shannon diversity (=0/3) of waterfowl.