مجله بوم شناسی کاربردی
پیاپی 6 (زمستان 1392)

Livestock grazing is a common human-induced activity with direct and indirect effects even on the ecosystems of protected areas. The present study analyzed the effects of different grazing management methods on species diversity and richness in the steppe rangelands of Saveh، Iran. Data were collected from sixty 2×2 m plots within the areas of three، four-years protected range management projects. Margalef’s and Menhinick''s indices، Simpson and Shannon-Weiner indices، and Pielou''s index were used to evaluate plant species richness، diversity، and evenness، respectively. All data analyses were performed in PAST and SPSS. According to the mean values obtained for Shannon-Weiner index، Nemati rangeland (with rest-rotation grazing system and moderate grazing intensity) and Shirali Baglou rangeland (with continuous grazing throughout the year and high grazing intensity) had high species diversity with no significant differences among them. However، Chagneh rangeland (with continuous grazing for six months and fairly high grazing intensity) had the lowest diversity. Low values of diversity indices indicated low species diversity in steppe rangelands. Moreover، Shirali Baglou rangeland had the highest species richness compared to the other sites. In the other three rangelands، both species richness and diversity decreased with increasing the grazing intensity. Despite poor range conditions in Shirali Baglou rangeland، intensive livestock grazing and the consequent rise in invasive species increased species abundance and hence، resulting in species richness and diversity in the area. Although over-grazing throughout the year can promote plant species richness through increasing annual species، consequent soil degradation and instability of rangeland ecosystem can be expected.

Constant urban development in today’s world has turned urban growth management into a main challenge in the 21st century. Obtaining spatiotemporal information about the pattern and rate of urban growth is critical to a better understanding of the urban growth process and practicing appropriate management policies. The present study investigated the trend of urban sprawl in Sari، Iran. First، land use and cover maps of the study area were prepared by processing multitemporal Landsat images from 1992، 2002، and 2010. Moreover، the urban growth of the city in 2010 was predicted by combining the Markov-cellular automata model with multi-criteria evaluation (overall Kappa = 83. 80%; area under the receiver operating characteristic curve ≈ 0. 69). Afterward، the same model was applied to simulate urban development in 2021 and 2031. Built-up area per capita and Shannon entropy were then measured to assess urban sprawl in Sari. According to the results of change detection and simulation of urban growth of the study area، the built-up area had increased proportional to population growth since 1992. The same trend is expected to continue until 2031 when the urban area will exceed 2800 hectares. In addition، based on the relative values of Shannon entropy، although Sari has not yet faced the urban sprawl phenomenon، the absence of physical barriers around the city necessitates comprehensive urban management approaches to control urban sprawl and prevent future environmental problems.

Following technological advancements and integrated municipal solid waste management in recent decades، various methods such as recycling، biotreatment، thermal treatment، and sanitary landfills have been developed and employed. Creating sanitary landfills is a major strategy in the integrated solid waste management hierarchy. It is cheaper and thus more common than other disposal methods. Selecting a suitable solid waste landfill site can prevent adverse ecological and socioeconomic effects. Landfill site selection requires the analysis of spatial data، regulations، and accepted criteria. The present study aimed to use the geographic information system and the analytic hierarchy process to identify an appropriate landfill site for municipal solid wastes in Najafabad (Isfahan، Iran). Environmental and socioeconomic criteria were evaluated through different information layers in the Boolean and fuzzy logics. The analytical hierarchy process was applied for weighing the fuzzy information layers. Subsequently، two suitable sites were identified by superimposing the maps from the Boolean and fuzzy logics and considering the minimum required landfill area for 20 years. However، proximity of these two sites to Tiran (a nearby city) made them undesirable landfill sites for Najafabad. Therefore، due to the existing restrictions in Najafabad، the possibility of creating landfill sites in common with adjacent cities should be further investigated.

The present study sought to determine the interactions between coral reefs and physicochemical properties of water (depth، temperature، salinity، turbidity، dissolved oxygen، pH، chlorophyll a، and water current velocity) and seabed type and slope in Kish Island، Iran. The study area was divided into 19 zones (eight zones with and 11 without corals). Physicochemical properties of water for each zone were extracted from previous studies over the past years. In summer 2010، field sampling of each zone was also performed using a conductivity، temperature، and depth (CTD) instrument. Non-metric multidimensional scaling (nMDS) and cluster analysis (CA) were then conducted to assess the dispersion of coral reefs and to determine the similarity of coral and non-coral zones، respectively. Finally، the similarity percentage (SIMPER) test was carried out in PRIMER 5 software to identify parameters differentiating coral and non-coral zones. The results of nNMDS analysis revealed differences in spatial distribution of coral and non-coral zones. According to CA results، the coral zone in the north of the island (CR6) and the non-coral zone in the northeast of the island (NC2) were similar in terms of physicochemical properties of water. However، they were significantly different from other coral and non-coral zones (p < 0. 01). SIMPER test showed seabed slope، water current velocity، salinity، depth، temperature، and turbidity to have the greatest contributions in the dissimilarity between coral and non-coral zones (25. 06%، 23. 38%، 13. 88%، 13. 82%، 8. 69% and 8. 61%، respectively).

Nonpoint source (NPS) pollution is a major surface water contaminant commonly caused by agricultural runoff. The purpose of this study was to assess seasonal variation in water quality parameters in Gorganrood watershed (Golestan Province، Iran). It also tried to clarify the effects of agricultural practices and NPS pollution on them. Water quality parameters including potassium، sodium، pH، water flow rate، total dissolved solids (TDS)، electrical conductivity (EC)، hardness، sulfate، bicarbonate، chlorine، magnesium، and calcium ions during 1966-2010 were evaluated using multivariate statistical techniques. Multivariate analysis of variance (MANOVA) was implemented to determine the significance of differences between mean seasonal values. Discriminant analysis (DA) was also carried out to identify correlations between seasons and the water quality parameters. Parameters of water quality index were measured through principal component analysis (PCA) and factor analysis (FA). Based on the results of statistical tests، climate (freezing، weathering and rainfall) and human activities such as agriculture had crucial effects on water quality. The most important parameters in differentiation between seasons in descending order were potassium، pH، carbonic acid، calcium، and magnesium. According to load factor analysis، chlorine، calcium، and potassium were the most important parameters in spring and summer، indicating the application of fertilizers (especially potassium chloride fertilizer) and existence of NPS pollution during these seasons. In the next stage، the months during which crops had excessive water requirements were detected using CROPWAT software. Almost all water requirements of the area’s major crops، i. e. cotton، rice، soya، wheat، and oat، happen in the late spring until mid/late summer. According to our findings، agricultural practices had a great impact on water pollution. Results of analysis with CROPWAT software also confirmed this conclusion.

Cypress (Cupressus sempervirens L. var. horizontalis) is one of the native conifers in Iran. It is found in Tange Soulak Forest Reserve of Kohgiluyeh and Boyer-Ahmad Province، Iran. An experiment in a completely randomized design with factorial 4×2×2 was performed to assess the factors affecting Cupressus sempervirens seed germination. Dieback، slope، and altitude were analyzed at four، two، and two levels، respectively. Results showed slope to have the greatest effects on seed characteristics and germination. In fact، all studied parameters including 1000 kernel weight، humidity of the seeds، speed and rate of germination، and the mean number of seeds in a cone decreased with increasing slope. Moreover، tree diameter had a low positive relationship with seed weight. On the other hand، although the seeds collected from trees with high rate of dieback had the lowest mean speed and rate of germination; dieback had significant effects only on the mean germination time. There were significant positive correlations between 1000 kernel weight and all seed and germination parameters. Therefore، it is suggested that for conservation and regeneration of this species in the region، seeds should be collected from mother trees with a larger diameter and heavier seeds located on low-slope lands.

Knowledge about long-term land cover/use changes is essential for evaluating and predicting their consequent problems by urban managers and policymakers. Remote sensing with landscape metrics is an effective tool for monitoring these changes in urban cores and their peripheral areas. During the recent decades، industrial and urban growth، and immigration of people into Isfahan metropolitan area (Iran) have affected its surrounding environment. The objective of this research was to quantify the changes of landscape patterns in the center of Isfahan during the last two decades. For monitoring spatial pattern changes، land use and cover maps of the area were prepared using supervised maximum likelihood classification of Landsat Thematic Mapper (TM) images taken in 1990 and 2010. In order to quantify the changes in landscape patterns during this period، we used several landscape metrics of each class type and total landscape. These metrics included percentage of landscape (PLAND)، number of patches (NP)، mean patch size (MPS)، patch density (PD)، largest patch index (LPI)، mean nearest neighbor (MNN)، contagion (CONTAG)، and Shannon’s diversity index (SHDI). The results of this study showed that the proportion of urban area and bare land significantly increased during the study period. Decreased mean patch area for agriculture and undeveloped land uses indicated that the landscape had been more fragmented in these two classes. The synoptic analysis of selected metrics for landscape level indicated that the metric values of MNNand SHDI to have increased and the metric values of LPI has reduced during the last two decades.