مجله بوم شناسی کاربردی
پیاپی 41 (پاییز 1401)

Environmental flow of the Beshar River was evaluated using Tennant's hydrological method, the comparison of the depth and speed of the water in the transverse sections of the river, and the needs of indicator fish species in different stages of the life cycle. Field samplings were conducted in October and January 2021 to monitor the status of fishes in the Beshar River and to collect cross-sections of the river. Indicator species were selected based on the expert judgement survey method. Among 23 fish species of the Beshar River, five species from the Cyprinidae family recieved the highest scores. The biological requirements of these species were extracted and used as the basis of comparison with the data of cross sections of the river. The obtained results showed that in the upper reaches of the river (between the two hydrometric stations of Qalat and Shah Mokhtar) the good class of the Tennant method, that includes 40% of the average annual discharge for the period of high flow (April to May) and 20% of the average annual discharge for the period of low flow (June to November), is suitable to provide the biological requirements of adult and larva of cyprinid species of the Beshar River, respectively.

The importance of the economic aspect of tourism usually overshadow many natural tourism destinations. Fereydounshahr county in Isfahan province, with pristine mountainous landscapes and diverse natural features, has high potential to attract many tourists. However, pristineness over much of its area suggests limiting the public access based on the degree of naturalness. Hence, the aim of this research was to classify Fereydounshahr county based on naturalness. Accordingly, nine effective indicators were weighted, using Analytical Hierarchy Process (AHP). Idrisi software was then employed to overlay the digital layers of criteria and produce a naturalness map, that consisted of five classes (from very natural to developed), based on Ordered Weighted Averaging (OWA) approach under six different scenarios. Results showed that developed areas under the AND scenario and the natural areas under the OR scenario have the largest range. The extent of desirable areas, including natural and relatively natural, increased when moving from risk aversion to risk taking scenarios. Based on the results, most of the natural areas were concentrated in western parts of the region, due to the long distances from the main roads, high presence of wildlife, and the presence of steep slopes.

Having accurate quantitative and qualitative information about the state of forest stands, is necessary for any basic management and planning, to reduce the effects of forest degradation. The current study aimed to model the destruction of Hyrcanian forests under the effects of density and volume (per hectare) variables, using logistic regression. In total, 252 plots of 1000 m2 area were measured. In each sample plot, species name, Diameter at Breast Height (DBH), height, density, volume and the presence or absence of forest degradation were measured and recorded. To model forest degradation, logistic regression model was utilized and Omnibus test, log-likelihood and pseudo r-square (Cox&Snell and Nagelkerke) coefficients were used to evaluate the  model. Results showed that the mean of density and volume of trees were 136.8 tree and 239.9 m3/ha, respectively. In addition, the results indicated that 46.82% of the study area was degraded. The results of correlation test showed that there was a srtong negative correlation between quantitative variables and the forest degradation. The independent variables of density and volume of trees were respectively explained 61.6 to 82.3% of the variance of the dependent variable (forest degradation). Among the input variables of the regression model, the effects of density and volume were significant on the forest degradation and it was possible to predict the changes of dependent variables (presence or absence of forest degradation).

Remote sensing data play an important role in environmental planning and monitoring. The current study aimed to investigate the land surface temperature (LST) and the effect of environmental factors on the LST, to identify the temporal-spatial patterns and determine the hot spots in the period of 2013 to 2019, using Landsat 8 images. The effect of spectral indices: Normalized Difference Build-up Index (NDBI), Normalized Difference Vegetation Index (NDVI) and Normalized Difference Water Index (NDWI) on the surface temperature was investigated. Results indicated that the lowest average temperature has occurred in 2019 and the highest LST was in the 2017. The results of Moran's index correlation also showed that the most clustering pattern of LST, with the Moran value of 0.85 was obtained in 2019, the highest correlation between LST and NDBI, with the R value of 0.76 in the 2015, the highest correlation between LST and NDVI in the 2015 (R = -0.56), and the highest correlation between LST and NDWI in 2013 (R = -0.53). Rasht watershed in Guilan province is affected by human factors and land use changes. Therefore, it is recommended to increase the vegetation cover in urban areas, reduce the change of pasture to agricultural area, and reduce forest destruction.

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.

Whooper swans have two old and new populations, the new population has reported since 2007. The current study aimed to investigate the genetic structure of this species and compare their gene pool, especially the new population. For this purpose, 110 samples from Iran and four European countries were analyzed, using six microsatelite loci. In addition to the samples of the emerging population in Fereydoonkenar International Wetland and the old population of Gilan, samples from Iceland, Sweden, Finland and Poland were also examined. The observed average heterozygosity ranged from 0.598 to 1.0 and the expected heterozygosity ranged from 0.661 to 0.950. Iceland in the extreme west of Palearctic had the highest observed heterozygosity of 1.0 and Iran in the easternmost part of the study area had the highest effective allele frequency (12.72). Also, the population of Iran showed deviation from Hardy-Weinberg equilibrium, except for one loci. Based on the STRUCTURE 2.3.4 results, the Iranian swan population had the highest gene flow due to the high dispersion of breeding colonies in northern latitudes. Therefore, the autumn and winter migrant swans have two populations in Fereydunkanar and one separate population in Guilan. Generally, the high allelic richness in the new population indicates a high conservation value of  the Fereydoonkenar wintering colony.