Journal of Natural Environment
Year:2012 | Volume:65 | Issue:2|Papers Count:11

Landscape metrics quantifies structural features of the landscape. One of the advantages of these metrics is a possibility to use them in fast cumulative assessment of the development activities in the environment. In this paper, the cumulative effects of road network expansion on the tree cover of Gorgan, Kordkuy, Aliabad townships in Golestan province were investigated. To prepare the required land use map, images of the Landsat TM (1987) and ETM+ (2002) sensors were employed. Based on previous studies in this area and towards cumulative effects assessment, seven related classes related were defined and distinguished in a supervised manner (maximum likelihood). Then, the effects of road network expansion and the cumulative effects of land use development on the tree cover were analyzed, using metrics of patch area, perimeter to area ratio, shape, fractal dimension, contiguity, proximity, and Euclidean nearest neighbor distance. With applying cross tabulation method, the amount of cumulative effects of development, and the road effects on the tree cover were calculated for a period of 15 years. Results showed that most patches which need protection from cumulative development are located 684-342 meters from the road. It was also determined we can assess the cumulative effects of development activities on tree patches, using landscape metrics. We also prioritized tree patches for protection and mitigation measures.

Lichens are composite organisms formed by a fungus and a green alga and 1 or a blue-green bacterium. They are recognized as being very sensitive to atmospheric pollution and respond to factors that influence human and environmental healths. Since 1860, lichen has been identified as a biological indicator to detect air pollution in Great Britain and Europe. Lichens have the high sensitivity to nitrogen dioxide, ozone, fluorine and heavy metals. The purpose of this study was lichen's chlorophyll changes in contact with different concentrations of 03 and N02 pollutants in urban environments. Lecanora muralis transported into special bags in contact with 03 gas at concentrations of 30, 100 and 200 ppb and N02 gas at concentrations 60, 100 and 200 ppb respectively. After one and three hours, they moved to the laboratory. Their chlorophyll (chlorophyll a, b, chlorophyll a + b and the ratio OD435 1 OD415) was extracted by immersion of the building 20 mg weight lichens in 10 ml DMSO solution. Data was analysed to evaluate the correlation and changes in amount of pollutants and concentrations of chlorophyll degradation. Destruction of chlorophyll with positive correlation (P<0.05) In samples exposed to 03 and damage of chlorophyll in contact with N02 hawith a negative correlation, level P>0.05 were observed. This study showed that Lecanora muralis can be used as a biological indicator in monitoring emissions of ozone and N02 in urban area.

Soil biodiversity is the origin of considerable goods for maintenance and extension of above ground biodiversity and environmental soundness. This study was carried out in Shirvan, Mashhad and Gonabad, three regions of Razavi and Northern Khorasan provinces, to determine soil characteristics and biodiversity in natural systems of arid and semi-arid regions. In each studied system, 10 locations were selected for sampling and 50 soil samples were taken from each system with 0.3m length, 0.3m width and 0.3m depth. Texture, pH, organic matter, diversity and abundance of soil invertebrates, nematodes, bacteria, protozoa and mycorrhiza were measured in soil samples. Results showed with increasing of mean annual temperature and decreasing the mean annual precipitation, soil texture became coarser, pH increased and organic matter decreased from 0.38 to 0.05 percent. Soil invertebrates were found only in natural system of Shirvan, with low diversity and abundance. Abundance of soil nematodes and bacteria was similar in three regions. But diversity of soil bacteria, abundance of protozoa and diversity of mycorrhizal fungi reduced with increasing of mean annual precipitation and decreasing of mean annual temperature. Mean species richness of soil bacteria in natural systems of Shirvan, Mashhad and Gonabad was 5.3, 5.8 and 3.5, respectively. Species richness of mycorrhizal fungi in these systems was 5, 5 and 4 respectively. Based on results, climate and edaphic conditions were caused to restriction of biodiversity in arid regions. But conservation of this level of soil biodiversity and its goods has the special importance.

As a result of human activities, Metal pollution has become one of the most serious environmental problems today. Phytoremediation utilizes plants to uptake contaminants and can potentially be used to remediate metal-contaminated sites. A pot experiment was conducted to compare the phytoextraction and phytostabilization potential of two plant species (Populus alba and Morus alba) for some elements. Thus, Cd (40, 80, and 160 mg/kg), Cr (60, 120, and 240 mg/kg) and Ni (120, 240, and 480 mg/kg) were added to the soil, shoots and roots of studied species. Associated soil samples were collected and analyzed by measurement of total concentration of Cd, Cr and Ni and then bioconcentration factor (BCF) and translocation factor (TF) calculated for each element. Our results show that none of the plants were suitable for phytostabilization of studied elements with root BCF<1 and TF> 1. In addition, Populus alba with the shoot BCF> 1 for Cd in all studied treatments and Ni in 240 and 480 mg/kg treatments were suitable for phytoextraction while Morus alba was suitable for phytoextraction of Ni with the shoot BCF> 1 in all studied treatments.

Industrial activities lead to an increase in heavy metal burden in rivers. Sediment and algae (Spirogyra sp.) samples were collected from the Shoor River to investigate their heavy metal concentrations. Dry and ashed samples of algae and sediment were digested using concentrated nitric acid. Heavy metals (As, Fe, Zn and Cr) concentration measured using an ICP-OES instrument (PerkinElmer, USA). Calculation of bioaccumulation factor (BAF) showed Spirogyra sp. can accumulate these metals and could be used as their bioindicator in the aquatic environment. Monitoring and control of heavy metals in this ecosystem was showed to be necessary based on high concentrations of the metals found in the sediment samples.

Many studies since 1977, in the southern coast of Caspian Sea revealed that the law-setback and low-lying coastal zone have been severely and increasingly impacted by rising sea-level. This rising continued until 1995. The rate of rising was nearly l3cm per year in this period (1977-1995). The general concept of setback determination is tended to introduce a buffer area between human activities (especially buildings) and a shoreline that is likely at the highest risk of sea-level rise and following damages. This study could help managers to solve many problems in the future, noticeably due to lack of criteria for determination of setback in this region. In this study a setback is introduced on the basis of critical levels of Caspian Sea and the results of coastal vulnerability assessment to sea-level rise in Mazandaran Province. This setback is composed of two parts called, vertical buffer and horizontal buffer. In this study, the CVI (Coastal Vulnerability Index) method is used for coastal vulnerability assessment to sea-level rise. The CVI includes 5 variables describing two dimensions, natural and anthropogenic. Final map is divided into 4 classes from low to very high vulnerable. Mean distance between very high vulnerable classes to the vertical buffer boundary is introduced as a horizontal buffer in each district.

Environmental degradation model is one of the Environmental Impact Assessment (EIA) methods in which ecological cumulative effects of human activities on his surrounding nature could be evaluated and quantified. As a special trait of Landscape Ecological Metrics is the ability of rapid assess and recognize of human activities in the shortest time. Thus in this study, we used a landscape degradation model to environmental impact assessment and degradation analysis of Korganroud watershed. To achieve this goal, the study area was divided into 12 sub-watershed depend on river system, as a working unit. In next step the ecological vulnerability, degradation factor and its intensity was computed for each region, using Landscape ecological metrics and classified depend on median. By using degradation table and importing model component, degradation coefficient was calculated and classified for each zone. By this way, each zone was ranked and Compared by degradation state into development and conservation level. Finally, from whole study area, 32% prone to further development levelland 27% level 2, 21 % need to be rehabilitated and 20% area that needs for conservation, are measured.

Brown bear (Ursus arctos) is one of the most important carnivores in Iran. However, information on its habitat associations is scared. Based on Ecological Niche Factor Analysis (ENF A) method, a summer habitat suitability model was developed for this species in the southern part of Alborz Protected Area. Our results showed that, brown bears prefer higher altitudes and northern aspects in their potential habitat. Water resources and presence of domestic animals found to be important predictors for bears occurrence while they avoid rocky terrains. Habitat suitability map illustrates those most favorite parts, located in northern parts of the protected area, including around 10% of total habitat.

Wild boar is distributed throughout Iran except highly arid areas. In recent years, however, population size of wild boar has increased primarily because of reduction in population size of natural predators such as leopard. Conversely, changes in land-use practices and increase in foraging of livestock in natural habitats has led to reduction of food resources and consequently, has forced the species to graze on plants, grown in agricultural fields. This has resulted in conflicts between conservation of wild boar and preservation of interest of local people. In this research, ecological niche factor analysis was used to develop habitat suitability model for wild boar in eastern Alamut hunting prohibited area and to determine factors, in particular, anthropogenic factors affecting species distribution. Results indicated that wild boar showed a tendency of moving towards villages, agricultural fields, river banks and areas of lower altitude. Forty villages were located inside or near the suitable habitat, as predicted by the model, of which 27% consisted of agricultural fields. This suggested a high conflict between wild boar habitats and interest of local people. To improve conservation status of eastern Alamut, it is important to reduce the conflict between wild boar and local population through management plans.

Population management of exploited species requires information on absolute density and abundance through reliable survey methods. The baseline information is further needed for population dynamics studies and determination of conservation status. The current population size of pheasant is totally unknown, because there is no official attempt to estimate population size in previous years. In this study, line transect based Distance Sampling method was used to yield population estimates in Sa'ad Abad Forest. Data from aural and visual counts were combined to calculate overall estimates. Adjustment was made in which an aural -detection was assumed to represent four birds per flock. Otherwise, the estimates were found to be underestimated. Results indicated that an unbiased estimation of overall density and abundance of pheasant for the entire 4000 ha study area, D ± S.E. = 0.35 ± 0.070 birds/ha and N ± S.E. = 1400 ± 280 birds, respectively. The cluster size of the species was estimated at, E (s) ± S.E. = 2.143 ± 0.139 birds/flock.