جستجوی مقالات مرتبط با کلیدواژه « species diversity » در نشریات گروه « اکولوژی »

Protecting wetlands and the life in them requires recognizing the biodiversity of these ecosystems. Waterfowl and shorebirds that are ecologically dependent on wetlands are used as environmental indicators. This research was conducted in the winter of 2021 in order to investigate the species diversity of wetland birds in Poldakhter city. Half-winter census data for a period of 13 years (2009-2020) was received from the General Environment Department of Lorestan province. Simpson's photo index and Simpson's dominance were used to investigate the species diversity of Poldakhter wetland birds. During the statistical period under review In Poldokhtar wetlands, 10 orders out of 19 orders, 16 families out of 84 is and 60 species out of 545 species identified in Iran were counted and recorded, which were 52.6 percent of the order, 19.04 percent of the family and about 11 percent, respectively. Iranian bird species have lived in Poldokhtar wetlands. 68.3 percent of Poldokhtar wetland bird species are in the category of unprotected and normal species, 26.67 Percent in the category of protected and protected species and 5 Percent that include species. Vanlellus gregarious, the world's highest conservation species (CR), and Aythya ferina, a vulnerable species (VU), Phoenicopterus minor, and Phoenicopterus minor Oak duck (Aythya nyroca) live in correct the endangered species (NT) category. In Poldokhtar wetlands, 53.3percent of birds were wintering birds, 30 percent were migratory birds, 8.3 percent were summering and hatching birds, 6.7 percent were normal (four seasons) and only 1.7 percent were summering birds without hatching. The results of the investigation of species diversity indicators of Poldakhter wetland birds showed that the year 2013 had the lowest species uniformity and the year 2018 had the highest amount of species diversity. Therefore, Poldakhtar wetlands are one of the important wetland habitats in the region and play an important role in the migration of waterfowl and wintering waterfowl.

Wetlands are one of the most unique ecosystems on earth, and their destruction is a result of direct and indirect human interactions. This study examines the abundance and diversity of birds in the Bandalikhan wetland and their relationship with water fluctuations and drought over a 10-year period (2012-2022). Bird census data was collected, and species richness and diversity indices were calculated. The changes in the water level were determined using the normalized water difference index (NDWI) and Landsat images. Rainfall, temperature, and drought index were extracted from meteorological records, and their correlation was analyzed. Results showed that common teal (Anas crecca) and mallard (Anas platyrhynchos) were the most abundant birds, and the highest values of species diversity and richness indices were obtained for the wettest year (2019). Linear regression revealed a positive and significant relationship between NDWI and the number of bird species (R2 = 0.72) and abundance (R2 = 0.74) of birds. A significant relationship was found between the drought index and the number of species (R2 = 0.62). To conserve the diversity and abundance of wetland birds, it is necessary to prevent large fluctuations in the water level, as this reduces the habitat suitability for birds.

Choosing management strategies are influencing the vegetation characteristics and plant diversity in rangelands. We have studied the effects of three management treatments including overgrazing, exclusure, and exclusure with restoration operations on vegetation characteristics of plant cover, composition, and diversity in Kiasar Chardange summer rangelands. In each management treatment, three random transects with the length of 50 m were established in the pasture and in five random plots of one square meter nested in the transects, the percentage of canopy cover, the composition of three palatability classes were recorded and the indices of plant diversity, plant evenness, species richness were calculated. For comparing the effects of different treatments on vegetation characteristics and diversity indices, an analysis of variance with equal subsamples was performed. Nonmetric multidimensional scaling was used to interpret the scattered patterns of plant compositions in relation to different management treatments. The results showed that all diversity, evenness, and richness indices were significantly different in three management treatments (p<0.05) The exclusure with restoration treatment had the highest indices of Simpson diversity (0.74), Shannon-Weiner diversity (2.12), Margalov richness (1.44), Mehnick (1.04), alpha diversity (6.13), and beta diversity (20.87). In contrast, the overgrazed site had the lowest values. The Camargo (0.77) and Smith-Wilson (0.87) evenness indices had the highest values for exclusure and the lowest values for exclusure with restoration treatments. Our findings could be a road map for future planning in similar sites. For rehabilitation of rangelands and improving plant diversity, restoration treatments in exclusures are recommended.

Soil is the richest and most diverse living community in any ecosystem. Soil organisms are responsible for the change and transformation of organic matter and the deformation and transport of nutrients such as nitrogen and sulfur. Therefore, they are an integral part of soil quality. In agricultural systems, useful macrofauna includes species that are involved in increasing crop yield and the ecological stability of the system. The objective of this study was the effect of agricultural systems (irrigated and rainfed) on the abundance and diversity indices of soil macrofauna in wheat fields of Ilam province, west of Iran. 

In this study, the abundance and biodiversity of the soil macrofauna arthropods in wheat fields of Eyvan (Ilam province) was investigated. Five samplings were performed during irrigated and rainfed wheat growth in the year 2019. For this purpose, five sampling units (replicates) were selected for ten fields. In each sampling unit, soil macrofauna was collected using pitfall traps and then counted. Diversity was calculated by Shannon-Wiener and Simpson indices, evenness by Pielou evenness index, and species richness with Margalef index. PAST software was used to calculate biodiversity indices. 

From 3753 macrofauna samples collected, 11 families belonging to different orders of insects and spiders were identified: (1) Diptera including Syrphidae and Muscidae, (2) Hymenoptera, i.e., Formicidae, (3) Coleoptera, i.e., Carabidae, Staphylinidae, Silphidae, Scarabaeidae and Cicindelidae, (4) Hemiptera i.e., Pyrrhocoridae, (5) insects larval from different families, and (6) spiders. The tiger beetles had the highest abundance in both irrigated wheat (25.48%) and rainfed (20.57%) fields. The T-test results showed that the agricultural environment change from irrigated to rainfed fields did not increase or decrease the number of families but increased the average total frequency (from 2100 in rainfed farms to 1653 in irrigated farms). Changing the agricultural environment from irrigated to rainfed caused an increase in the Shannon index, Simpson and Margalof; also, this change of agricultural environment from irrigated to rainfed has caused a decrease in the value of the Pielou index. The results showed that the Shannon-Wiener index and the Margalef richness in the rainfed wheat fields were significantly higher than in the irrigated fields (P≤0.05), however, the Simpson diversity in rainfed fields was higher than in irrigated wheat fields, but this difference was not significant (P≥0.05). Also, the Pielou evenness in the irrigated fields was higher than in rainfed, but this difference was insignificant (P≥0.05). The results also showed that the highest and lowest number of arthropods trapped in pitfall traps in rainfed fields were related to tiger beetles (21.4 ± 4.87) and red bugs (1.68 ± 0.18), respectively, and in irrigated fields, it was related to tiger beetles (13.60 ± 2.82) and dung beetles (2.16 ± 0.16). In general, the results showed that the frequency and diversity of soil macrofauna in the rainfed wheat fields were higher than in irrigated wheat fields. 

 The diversity of soil macrofauna arthropods in rainfed wheat fields was better than in irrigated wheat. Less use of chemical pesticides and agricultural machinery in rainfed wheat fields improves soil physical properties as well as provides suitable habitat for soil macrofauna arthropods, which increases diversity. Useful soil macrofauna is very sensitive to environmental changes, so as the environment is destroyed, the diversity and number of these macrofauna decrease. In general, according to the obtained results, it is necessary to avoid the excessive use of chemicals in irrigated wheat fields and to provide conditions for improving the biodiversity of soil macrofauna. These conditions can be created by reducing the use of chemicals on farms, but if you cannot for any reason, avoid the use of chemicals on farms, use other methods such as fallow, crop rotation, and also the cultivation of legumes in the agricultural program of the region provided these conditions.

The objective of this paper was determining population and species diversity of water birds and waders in Gandoman wetland during one year from mid-September 2017 to mid-September 2018 using SDR-IV software. Result showed from 70 identified birds, 28 species were waterfowl and 42 species were waders. The largest population was belong to Fulica atra. Anatidae with 33.19 percent frequency was the largest family and Burhinidae with 0.003 percent was the smallest family. Winter had largest bird counting (14413 birds) and summer had the lowest bird counting (4039). Results obtained using biodiversity index showed that spring had the biggest diversity in terms of Shanon-Winer (2.97), Simpson (10.71) and Margalf (6.69) diversity and biggest evenness (0.92) in terms of Smith & Wilson. The largest species richness was found in spring (60 species) and the lowest one was found in summer (40 species). The largest bird frequency (bird number) was belong to waterfowl (81.57 %) and the lowest frequency was belong to waders (18.43). In contrast, the largest number of species (60 percent) was belong to waders and the lowest one was belong to waterfowl (40 percent). The results showed that Gandoman wetland had the highest numerical values of richness and evenness of water birds and waders in spring, and this indicated the quality and desirability of the wetland in spring compared to other seasons.

In the present study, the wintering birds of the artificial wetlands of Yazd province in 1393, 1395 and 1396 were studied. This study is one of the first studies conducted with the aim of preventing the drying process of the wetland by emphasizing on maintaining water rights and protection of migratory birds in the artificial wetland of Yazd. Data from winter and autumn counts which were carried out in 2014, 2016, and 2017, were gathered and analyzed. In this study, 48 bird species (18 species of aquatic, 18 species of waterside and 12 species waterside) were identified. The highest numbers belonged to the Fulica atra (528 individuals), Sturnus vulgaris (500 individuals) and Anas platyrhynchos (130 individuals) respectively. Among aquatic birds, the highest number of species were represented by the family of Scolopacidae (6 species). Furthermore, the family of Rallidae represented the highest number (531 individuals comprising of 3 species). The highest and lowest numbers were 2750 and 819 individuals in 2017 and 2016 respectively. The highest evenness was observed in 2016 (0.62) and the lowest in 2014 (0.39). The most diversity of Simpson and Shannon-Winer in 2016 were 4.32 and 2.01 respectively. This study has shown that the artificial wetland of Yazd, in addition to protecting and maintaining water birds, is also important for the conservation and providing habitats for terrestrial birds and thus protecting it should be of utmost importance.

Nowaday, forest structure issue is one of the main ecological debates in forest science. Determination of forest structure characteristics is essential for investigating stands changing process, silviculture interventions and revival operations planning. In order to investigate the structure of Ghale-Gol forests in Khorramabad, a set of indices such as Clark and Evans and uniform angle indices, mingling, domination and differentiation were used based on the nearest neighbors. In so doing, 80 circular sample sizes with 12 (acer) areas were collected in the field using a random sampling pattern and these plots were analyzed by Crancod (Ver.1.4) software. Based on the results, the average of Clark and Evans and uniform angle indices were calculated 0.936 and 0.449, respectively. These results showed that the samples have a random distribution with the tendency to be uniform. Also, the result obtained from the average of mingling index was 0.181 that indicated low species mixture. In an investigation on the diversity of tree dimensions, the average of domination and differentiation indices of the crown area were 0.449 and 0.519, respectively. This in turn shows that neighboring trees had a clear difference with each other in terms of the crown area. As the results showed, in the Zagros forests which often consist of wide and pure oak stands, using small sample size reduced time and cost of field survey, recordation of the sample size position, trees and shrubs accurately.  Surveying and monitoring different forest features are more probably suitable for quantification of forests structure.

Biodiversity is one of the important concepts in ecology and vegetation management, and plays an important role in the health, production, and evaluation of ecosystems. Species diversity is a major part of biodiversity and one of the most important parameters of ecosystem changes. In this research, the data of the rangeland evaluation different climate zones of Isfahan province were used in five range sites of Alavijeh, Charmshahr, Khondab, Kalahroud and Mouteh to study the variations of the diversity and richness of species with production in the steppe rangelands. The sampling was done on random -systematic and the density and percent of vegetation conopy of each species along the transects using constant plots and production are also estimated by double measurement using the coating. The diversity numerical indices were calculated using Excel, PAST, Ecological Methodology and PRIMER softwares. In order to investigate the relationship and presentation of the model between species diversity indices with parameters (production, density, and canopy cover percentage) from pearson correlation analysis and multivariate regression analysis were used in spss software. The results from the correlation analysis mirror the significant correlation between some species diversity indices and vegetation parameters. The results from the correlation analysis show mirror the significant correlation between some species diversity indices and plant cover parameters. The correlation coefficient of different indices of biodiversity in different regions with density of 0.76 to 0.98, vegetation percentage is 0.74 to 0.92 and production is 0.71 to 0.92. Also, the results from the multivariate regression analysis reflect the effect of the density, vegetation of herbaceous broadleaf (%), and total Coverage on the production. In the rangelands under study, Menhinickchr('39')s richness index was able to justify 13.1% of the changes of herbaceous broadleaf productions. Among the species diversity indices, Hill’s index N2, Simpson index, and McIntosh index and among the evenness indices, Camargochr('39')s index and Shannon-Wiener’s index had the most connection with production and they can justify its changes.

     Several factors affect the crop yield and weeds are among the most important factors reducing crop yields .There are high tendency to develop alternative methods of herbicides for natural control of weeds in organic products. One of the alternative methods to manage weeds is intercropping. Intercropping is growing two or more crops simultaneously in a piece of land during a growing season. The objectives of the present study were to examine the effect of cereal- legume intercropping on weeds growth. A field experiment was conducted in College of Agriculture of Darab, Shiraz University during 2014-2015.      In the experiment 16 treatments (five weed free monocultures of wheat (M1), barley (M2), triticale (M3), pea (M4), faba bean (M5), 5 weedy monocultures of wheat (WM1), barley (WM2), triticale (WM3), pea (WM4), faba bean (WM5), and six replacement intercropping treatments of wheat + pea (I1), wheat + faba bean (I2), barley + pea (I3), barley +  faba bean (I4), triticale + pea (I5) and triticale + faba bean (I6) without weed control) using a randomized complete block design (RCBD) with three replicates were studied. Cereals and legumes were planted simultaneously at 23 November 2014. Planting operation was conducted on both sides of the ridges.    Weed diversity was calculated by Shannon diversity index:     N=Total number of plants in each plot of one square meter, Ni= number of species i plants, S= total number of species, and H= Shannon diversity index. This index value ranging from zero to five, higher index value, greater diversity.      The results showed that the lowest density and biomass of weeds were obtained in both sole culture and intercropping of barley. For instance, the lowest weed biomass was observed in monoculture of weedy barley (1 g m-2), intercropping of barley + faba bean (12.67 g m-2) and intercropping of barley + pea (56 g m-2). The weed density at weed free sole culture of barley (30 plants m-2) was lowest that followed by barley + faba bean intercropping (81 plants per m-2). The lowest species weed diversity was obtained in barley + pea (zero) and weedy barley (0.007), respectively. The weed diversity of most intercropping treatments was similar or less than that of weedy sole culture. In General, pea or faba bean monoculture had greatest weeds density and biomass, because slow growth and late seedling establishment. However, cereals especially barley controlled weeds properly, due to greater growth rate, higher height and greater density than those of legumes. Intercropping of pea and faba bean with cereals reduced weeds growth and had lower weeds density and biomass than those of pea and faba bean weedy monocultures. In order to increase of legume yields, more density of legume should be intercropped with cereals.      In general, intercropping treatments caused a significant decrease in weeds density and biomass compared to the legumes monoculture. In this experiment barley and triticale due to good properties such as fast growth, high plant height and more shading could considerably control weeds in both monoculture and intercropping treatments, reducing significantly weeds density and biomass in itself sole culture and intercropping treatments. To reduce the weeds growth in faba bean and pea, which have a poor competitive ability with weeds, intercropping with cereals, especially barley and triticale, in the south of Fars province is recommended. However, intercropping is one of the ways to reduce weeds in the long term and its effects on weeds in the long period will be much more.     The authors would like to acknowledge the College of Agriculture and Natural Resources of Darab, Shiraz University, to finance the project and all those who helped us in this project.

The aim of this study was to investigate the flora, life form, chrotype, diversity and evenness of accompanying species of Artemisia melanolepis Boiss. and Artemisia aucheri Boiss. in the south east of Sabalan. Species were collected and identified. Overall, 82 identified plant species was belonging to 23 families and 61 genera. Asteraceae, Fabaceae, Lamiaceae and Poaceae families were the dominant families and Astragalus and Poa were the dominant genera in studied habitats. According to the Rankaier's system the identified species in the study area, were belonged: 69.5% to hemicryptophytes, 10.9% to therophytes, 13.4% to chamaephytes and 6% to geophytes, respectively. In the habitats of A. aucheri and A. melanolepis, hemicryptophytes is the dominant with 71 and 78.3% of accompanying species respectively having the highest frequency. In the habitats of A.aucheri, chamaephytes species with 18.4% is the second dominant life forms. The second life form of the accompanying species of A. melanolepis, with 13.5% is the therophytes. Geographical distribution of species in the study area indicates that the Iran-Turanian region with 56.09% has the highest frequency. In the habitats of A.aucheri and A. melanolepis, species with geographical distribution of Iran-Turanian region with 24 and 16 species, respectively is dominant. Results of the numerical diversity indices (Simpson and Shannon-Wiener) and evenness (Simpson and Smith-Wilson) in the study habitats shows that Simpson index have no significant differences in the accompanying species of two Artemisia species but the Shannon-Wiener diversity index in different elevation and aspects have a significant difference. Using the results of this study, in addition to the basic information and understanding of A.aucheri and A.melanolepis habitats, also in the habitat of these species for the improvement and reclamation the identified species can be used.

To study the weed population indexes of onion (Allium cepa L.) monoculture systems in the Jiroft area, four onion continuous monocultures, including less 3 (S1), 3-5 (S2), 5-8 (S3), more than 8 (S4) years and long-term fallow (F) were sampled by systematic randomized method in three stages: before sowing, 60 days after planting and 30 days after harvest, during 2015-2016. Of the 28 weed species, 16 species were observed in all systems. The analysis of variance showed that the monoculture system had a significant effect on the density of the weed species including Cyperus rotundus, Malva neglecta, Heliotropium europium and Chenopodium murale and the density of these species were was 14.64, 14.16, 13.90 and 11.97 weeds per square meter, respectively. Increasing the in monoculture duration from three to more than eight years led to enhancing increased the density of the weed species. The assessment of the onion monoculture duration had a significant effect on the weed diversity indexes. The maximum indexes of Simpson, Shannon, Menhinick and evenness in the S4 system were 0.92, 2.76, 0.90 and 0.99, respectively, and they were the lowest in the F system (0.78, 0.89, 0.78, and 0.95, respectively). In general, the onion continuation cropping increased the weed density of each weed and significantly enhanced the species diversity indexes.

Leeches as one of the most important components of the aquatic ecosystem has gained so much attention. Due to their parasitism, they are commercially considered as dangerous factor in fishery and biologically as potential indexes for chemical pollutant in aquatic ecosystems. So their identification and population dynamics in different aquatic habitats would be valuable. Species diversity of fresh water leeches in three rivers in east of Tehran province, Lar, Jajrood and Hablehrood rivers, were studies through 6 months in 2015. During the sampling procedure from 10 station in 3 rivers, two species, Placobdella costata and Erpobdella octaculata were collected which the latter was more frequent in all the sampling points. Study on population dynamics of Erpobdella octaculata showed no significant difference among different sampling points; however, population in different sampling months showed significant difference and the most collected samples belonged to May; it was assumed that the highest population in May would be due to the higher population of their host Ephemeroptera, favorite temperature of water and low level of chemical pollutants.

Lentils are one of the most important legumes in agricultural systems. Unfortunately, they compete poorly with weeds due to morphological characteristics. Weed control is therefore necessary to prevent yield loss. Yield is not generally affected by single-species weed interference but the presence of several different weeds leads to reduced crop yields (Song et al., 2017). Therefore, the study of multi-species weed interference provides useful information at the field level. Regarding the material mentioned in this study, the interference of multi-species weeds with lentil in natural field conditions was investigated.
This experiment was conducted on one of the lentil fields of the Agricultural and Natural Resources Campus of Razi University in Kermanshah. Sampling was systematically carried out in two stages in a network of regular points with 7-meter spacing using a 1-square meter quadrate. The geographic coordinates of each sampling point were recorded using a GPS device. The first stage of non-degraded sampling was done at the the pre-flowering stage of lentil and recorded density, height and the percentage of weed canopy and lentil canopy. The second stage of sampling was carried out precisely at the same points of the first sampling. The recorded variable in this stage included dry weight, weed density, and lentil yield. Relationship between weed density, canopy percentage and height with lentil yield were investigated using regression function.
The results showed that the regression relationships between weed density, canopy percentage and height with the lentil yield were significant (p≤0.01) and the function was able to express the variations of the dependent variable affected by independent variables. According to the model, lentil yield was significantly affected by weed density and canopy percentage (p≤0.01). Thus lentil yield decreased with increasing weed density and canopy percentage with decreasing coefficients of 0.62 and 0.67T respectively. Weed height did not show a significant effect on yield. Correlation coefficients between weed density and lentil yield indicated that there were significant negative correlations between three weeds of high density including Chenopodium album, Polygonum aviculare and Sinapis arvensis with lentil. In a study about the relationship between weeds and autumn wheat, researchers also reported that just three species of the seven weed species in the field had a negative effect on wheat yield (Noroozi et al., 2003). Mean comparison of lentil yield affected by different levels of weed canopy indicated that the effect of the weed canopy on lentil yield was significant. The highest yield was observed when the weed canopy was 0-10% and the lowest when the weed canopy was 60-70%. Investigating the relationship between weed canopy percentages and lentil yield showed that there were significant negative correlations between the four weeds including Sinapis arvensis, Picnomon acarna, Cerastium perfoliatum, and Convolvolus stachydifolium with yield. In general, the different levels of weed canopy percentage had a significant effect on lentil yield. The yield showed a decreasing trend with increasing weed canopy percentage. Research has also shown that plants are affected by increasing canopy levels of adjacent plants (Cressman et al., 2011).
The results of the study indicated the significant effect of weeds on lentil yield, so that increasing the density, weed density, and canopy can reduce yield. The results also showed that weeds can have negative or positive effects on crops. Among weeds registered in the field, only a few weed species had a significant negative effect on lentil yield.

Numerical indices of diversity, in their entirety, do not provide a complete description of distribution and richness of species. Therefore, parametric indices should be also considered in studying of plant communities. In this regard, the indices of species richness, evenness and diversity related to the ecological sites of Cher mountainous rangelands of Urmia were calculated. The diversity profiles and rank-abundance species curves related to each of the sites were plotted and finally species diversity distribution models were fitted to each of data set using the Goodness-of-fit test and then best model was selected. There was no significant difference in terms of numerical indices among sites, but each of the indicators showed one of the sites be more diverse and made it difficult to distinguish the ecological site with high diversity. The difficulty of interpreting results considering the curves of diversity profile and rank abundance-species was also observable and the pattern of species distribution could not be understood. Therefore, surveying diversity using speciesabundance distribution models and fitting the data with current species distribution models was carried out. The results indicated that Log-normal model can be fitted to all the types with moderate grazing intensity (sites far from resting points). based on the results considering to the proper grazing intensity could conserve the plant diversity.

A fundamental characteristic of mountain ecosystems is the drastic change in vegetation along elevation gradient that promote the diversification of plant species. The aim of this study is investigation of plant species richness and diversity patterns along elevation gradient in mountainous environments of Shaskouh Protected Area, South Khorasan Province. Vegetation sampling was conducted in five elevation zones (1200-1000, 1500-1200, 2000-1500, 2500-2000 and 2850-2500 meters above sea level). Abundance distribution models, numerical indices of species diversity, richness, dominance and evenness were determined for each zone. Also, to ordination the species composition along the elevation gradient, Detrended Correspondence Analysis (DCA) was used. The results showed that in mountain environments, elevation gradient has significant effect (p≤0.01) on plant species diversity and richness. Maximum species richness (27 taxa) were observed at low elevation (1500-1200 meters above sea level) and minimum species richness (10 and 7 taxa) were found in the moderate classes of elevation (2000-2500 meters above sea level) and the high classes of elevation (2500-2850 meters above sea level). As well as, the results showed that species diversity was low at low elevations, then with increasing elevation reaches its maximum at middle elevation, then decreases at high elevations (above 2500 meters above sea level).

The avifaunal diversity and population fluctuation of birds of Karun River ecosystem in Ahvaz City was studied for period of six months from April-2015 to September-2015 based on observational and total count methods with Zeiss binoculars (10×40) and telescopes (15×60). A total of 1919 bird individuals from 41 bird species were recorded in Karon River ecosystem. Out of the total 41 species, 8 species(19.51%) of all detections belong to swimmer waterbirds, 8 species 19.51% of bird species belong to wading birds and 25 species (60.98%) terrestrial birds, that 22 species of them were breeder (12 species belong to terrestrial birds, one species to water birds and 9 species to wading birds). Reduction population of waterbirds in 2015 compared to 2001 was 95 percent and breeding population reduction was 20.76 percent. The terrestrial birds were dominant with 836 individuals in spring and 390 individuals in summer as compared to water birds, 529 individuals in spring and 164 individuals in summer. The highest waterbirds abundance was recorded for Cormorant Phalacrocorax carbo (3.66% in spring), the highest terrestrial birds abundance was recorded for House Sparrow Passer domessticus (15.16% in spring) and Swallow Hirundo rustica(9.74% in summer), and the highest wading birds abundance was recorded for Little Egret Egreta garzetta(57.77% in spring). The highest species diversity i.e. Shannon’s index (3.27), species richness i.e. Margalef’s index (R1 = 6.227), species evenness, i.e., McIntosh’s index (E = 0.6733) and Fisher alpha’s index (11.26) was recorded for all birds. Six species of protected and one species of globally threatened species observed in Karun River ecosystem. The aim of this study demonstrates the importance of Karun River Ecosystem in Ahvaz City limits to protect the birds.

The regeneration is one of the most important phenomena in forest ecosystems and the most important factor of development and sustainability of forests. Assessment of the regeneration is one of the best criteria for monitoring forest function stability. The aim of this study was to investigate the spatial variability of regeneration diversity and its relationship with tree species diversity in Zagros Forests, Kermanshah (Gahvareh).This study was conducted at 70 hectares of Gahvareh forests. In this area, 67 sample plots (400 m2) were used in a 100 × 100 m sampling grid. In each plot, total number and species of trees and all seedlings which had diameter less than 7.5 cm were recorded. We also recorded asexual regeneration in ¼ plots (100 m2).Then the spatial continuity was described using geostatistics (variogram and cross- variogram). The variograms of variables revealed the presence of spatial autocorrelation except evenness index (Sheldon) of trees and sexual regeneration. They had spatial dependence at large ranges that showed the large distance of dependency and homogeny of condition. In addition, cross-variograms indicated a strong spatial relationship between diversity of sexual regeneration and tree diversity and between diversity and richness of asexual regeneration and tree abundance.

Heavy grazing including activities can threaten plant species diversity and selective grazing of livestock can lead to a steady rise in non-palatable vegetation and, as a consequence, the dominance of a few species in a region (Anderson and Hoffman, 2007). To assess the impact of environmental factors on different ecosystem species, diversity measurement methods can be used. In fact, the species diversity in an ecosystem reflects the impact of various environmental factors on ecosystems and their status (Hasenauer et al., 2000). Nowadays, overgrazing can be observed in meadows and pastures surrounding the Golestan National Park (Akhani, 2005) and this could become a serious threat to the ecosystem of the region.
Considering the importance of the above, In order to understand the different contributions of various components of diversity and the composition of plant communities in different habitats under a grazing gradient, an experiment was conducted in Golestan National Park (the Park) and surrounding areas during 2011-2012. To this purpose, four habitat types were selected consisting of: un-destroyed habitat in the Park, abandoned habitat (areas of the Park that have been uninhabited since 1963), habitat under seasonal grazing (Ghorkhod Protected Area and surrounding areas) and heavy grazing in villages surrounding the Park. Six replications were determined for each habitat. Species richness and percentage of canopy cover were measured using 1 m2 sampling plots at each replication. In this experiment, SHE analysis was used to separate the components of diversity. In addition, to gain more awareness about species composition of the different habitats correspondence analysis was used for ordination.
The results showed that diversity and species richness reduced with increased grazing intensity in the study habitats. In addition, the frequency distribution of species in the un-destroyed and abandoned habitats and in habitats under seasonal grazing was fitted to a log normal model, and for the habitat with heavy grazing it was fitted to a logarithmic series model. Based on the logarithmic series distribution model most species have been observed in lower abundance and a few species have a maximum frequency which underscores the dominance of a small number of plant species. This is the reason why plant species composition in habitats under heavy grazing tends towards the non-palatable species. In an experiment conducted by Todd and Hoffman (1999) heavy grazing led to reduction of palatable species. In addition, the composition of plant species from different habitats was various and the similarities between species and families were different in the diverse habitats: The species and families recorded in habitats under heavy grazing bore the greatest similarity to species and habitats belonging to seasonal grazing, abandoned and un-destroyed habitats, respectively.
The results show that excessive exploitation by grazing has led to the reduction of plant species diversity and a change in the composition of plant communities in the Golestan National Park and its surrounding area. Therefore, more attention to this destruction of the genetic reservoir would appear to be necessary.