جستجوی مقالات مرتبط با کلیدواژه « altitude » در نشریات گروه « علوم پایه »

Plants are one of the important sources of fatty acids. Types of saturated and unsaturated fatty acids are widely used in food industry, health, plant ecophysiology and chemotaxonomy. This research was conducted with the aim of investigating the oil content, fatty acid profile and chemotaxonomic relationships of some plant species of the Apiaceae family in Iran. Oil extraction was done by soxhlet method and compounds were separated by gas chromatography (GC) after derivatization in the form of methyl ester. Species cluster analysis was done with distance algorithm between two data and Euclidean similarity matrix using PAST 3.17 software. Based on the results, the average oil yield of plant species was estimated between 5.1% and 26.18% and there was a high positive correlation between the altitude of the habitats and the oil yield. Petroselinic acid (C18:1(n-6)) and alpha-linolenic acid (C18:3(n-3)) were the main compositions of fatty acids of all species. Oleic acid and gamma-linolenic acid were detected only in Ferula and Pimpinella species, respectively. The percentage of total omega-3 fatty acids varied from 10.42 to 17.99 among species. Smyrnium cordifolium, Ferulago angulata, Tetrataenium lasiopetalum and Conium maculatum were rich in petroselinic acid (60-78%). Chemical dendrogram based on 18 fatty acids with high similarity coefficient distinguished Ferula species in one group and Conium in a separate group similar to botanical classification. The results show that the fatty acid composition of the seeds of some genera of the Apiaceae family, together with the morphological and molecular characteristics, can be used as a tool to solve the taxonomic complexities between the tribes and genera of the Apiaceae family. to be used in the flora of Iran.

Awareness of the condition of soils in forest areas and the study of the effects of various activities on soil properties is very important and effective in forest management. Soil properties change under the influence of various environmental factors such as altitude. The aim of this study was to investigate soil indices at altitudes of 400 to 1700 meters above sea level in a series of Benshaki forest area in Ramsar city in Mazandaran province.

For sampling soil variables in each altitude floor, 3 sample plots of 400 square meters at intervals of 100 meters from each other were identified.

Soil samples were taken from 0-10 and 10-30 cm depths. Soil properties measured include sand content, clay content, nitrogen content, potassium content, carbon and organic matter content and soil pH.

The result of this study showed that the effect of altitude on soil characteristics (percentage of sand, percentage of clay, percentage of nitrogen, potassium, percentage of carbon and organic matter and soil pH) is significant in different altitude classes (P ˂).

Seed performs a significant role as the most influential factor in the transfer of tree species heritability and forest sustainability. The goal of this study was to examine the effect of altitude from sea level on seed production and regeneration of oriental beech in managed forests. For this purpose, 50 paired sample plots with 2 × 2 m at 1100, 1600 and 2000 m.a.s.l were established. For different experiments were transferred the collected seeds to the seed laboratory. The germinated seeds counted at each sample plot on spring in order to regeneration survey. According to the obtained results, 1600 meters consist of the highest seed, 2000 meters encompass the highest regeneration and 1600 include the un-healthiest seeds. In addition, the maximum seed eaten by insects related to the height of 1600 m. furthermore, 1000 seed weight at the 1100, 1600 and 2000 m were determined to be 207.684, 244.144 and 304.237 grams, respectively. Seed weight appears to be lower in frequently seed years than in regular years. According to the results, the best height for producing and collecting beech seed is at 2000 m.a.s.l. Therefore, the establishment of a seed production station as well as a temporary nursery at this altitude can create a suitable ground for seed reproduction and production in areas of equal height and homogeneity.

Climate change along with human development created additional pressure on ecosystems, so in many cases it has caused a decrease in biodiversity. Global climate change continues as a global crisis. Climate change does not affect all habitats and species equally. Rather, large species are more affected by climate change and habitat change and are more vulnerable than other species. Also, studies show that the countries of the Middle East have been severely affected by the effects of climate change. Large herbivores, especially red deer (Cervus elaphus), are not only affected by habitat changes resulting from climate change, but also the increase in temperature has reduced the survival rate of calves and impaired reproduction. The Caspian red deer in Iran has lost a lot of its population under the influence of habitat destruction and illegal hunting, and today the remaining population tolerate additional pressure from climate change. Central Alborz Protected Area is considered as a main breeding habitat of Caspian red deer, which is affected by human development and climate change today.

In this study, in order to investigate the impact of climate change on the red deer population, temperature and precipitation data of two meteorological stations, Nowshahr in the lower elevations, and Baladeh in the southern elevations, were used. Also, presence and non-presence points of the species were collected random transects direct observation, as well as pictures of camera traps.

Using 19 climate parameters to evaluate habitat suitability in the future, it revealed that continuation of the climate change process in four optimistic to pessimistic scenarios using five MaxEnt, RF, ANN, GLM, MARS algorithms, the suitability of low altitude areas in the sectors of north and east will be reduced, and will be increased towards to highlands in southwest. The results showed that the parameters of average annual temperature, average daily temperature, average temperature of the dry season, average temperature of the hottest season, annual rainfall, rainfall in the wettest season, and rainfall in the hottest season have an effective role in determination of the habitat suitability of the species. The results of the climate data showed that the altitude plays an effective role in reducing the effects of climate change, so that the climate change in the downstream areas has a significant intensity compared to the high areas. According to the change of habitat suitability resulting from the continuation of the climate change, Kojoor forest zone shows the relative stability of desirability for the studied species in the present and future, but the Kheyrud forest road with a total length of more than 50 km is located in the depth of this area, where the traffic of vehicles of herders, ecotourists and especially illegal hunters have facilitated access to this habitat, which is the most main threat to survival of red deer in this habitat.

With the continuation of climate change and its effects on the habitat in the future, it is expected that female deers will be observed in unsafe parts of the habitat. Therefore, for conservation of the Caspian red deer population in the central Alborz Protected Area, robust management measures are needed based on created habitat changes in the future.

Considering the critical conditions of Lake Urmia, identifying bacteria with the ability to live in extreme environments is valuable in terms of microbial applications and tolerance of the existing biological conditions, and it helps us to better understand the surrounding environment. In this study, the most abundant microbial branch in the soil samples obtained from three different heights of 10, 150 and 250 meters of Qale Kazem Khan Mountain, which is located on the shore of a very salty lake in Urmia, has been investigated.

The soil samples were collected to identify and classify Proteobacteria    subgroups using 16S rRNA sequencing using Next Generation Sequencing (NGS) as well as FLASH genetic software and UCHIME algorithm to identify the obtained sequences.

Altitude change affects the abundance of Alphaproteobacteria and Betaproteobacteria. The abundance percentage of Alphaproteobacteria has a direct relationship with altitude, while the abundance percentage of Betaproteobacteria increased with the decrease in altitude.

in the overview the percentage of Proteobacteria abundance the samples has an inverse relationship with the increase in height, whereas in the separate examination of the microbial groups, a significant relationship between the increase and decrease in abundance and the height of sampling is observed. Also, two unknown and unclassified genera in the  Deltaproteobacteria order were also identified which a very high frequency percentage (18-27%) among the data had related to the three samples.

Biodiversity is an important structural feature of dynamic and complex forest ecosystems. One of the most challenging and important issues in assessing the structure of forest ecosystems is understanding the relationship between biodiversity and environmental factors. Hyrcanian Forests are considered a biodiversity hotspot in the world and have special and unique features that have led to an emphasis and importance of biodiversity conservation in these forests. The aim of this study was to investigate the effect of biotic and abiotic factors on the diversity and richness of tree species in Hyrcanian Forests from the west of Gilan province to the east of Golestan province. For this purpose, using 655 fixed sample plots (0.1 hectare), the diversity of trees in 3 provinces in the northern Iran from east to west of the Caspian Sea was analyzed. A combination of non-parametric models including random forest (RF) and support vector machine (SVM) and linear regression models were used to investigate the relationship between tree diversity and biotic and abiotic factors. Biotic and abiotic variables included the number of trees per hectare, diameter, respectively. Basal area (BA), Basal Area in Largest tree (BAL), slope, aspect and elevation. Evaluation statistics including the coefficient of determination, RMSE and percentage RMSE error showed that the random forest model was the best model to determine the relationship between biodiversity and environmental factors and has suitable accuracy for determining biodiversity changes in the northern forests of Iran.

In the present study, the effect of altitude on the morphological characteristics and also essential oil content and composition of Inula helenium L. was studied. This plant was collected in the flowering stage in the first half of July 2017 and 2018 in different altitudes of the Zanjan region (from 1200 to 2400 meters above sea level) and the growth traits of plant organs including leaves, stems, flowers, and roots were measured. In autumn, at the end of the annual growth period of the plants, plant rhizomes were harvested to evaluate essential oil content and composition. The Clevenger device was used for 3 hours for essential oil extraction and the GS-MS device was used to identify the constituents of Inula helenium essential oil. The results showed that there were significant differences in all growth traits and essential oil depending on the altitude of the region. Although, the growth traits of Inula helenium such as leaf and stem dry weight, leaf width and length, leaf number, and plant height decreased with increasing altitude, but the rhizome dry weight and diameter, and essential oil content increased with increasing altitude. The essential oil components of I. helenium were changed with increasing altitude so that the content of geranyl acetone, verbanol, α-pinene, isoalantolactone and valencene increased with increasing altitude. Also, the content of α-selinene decreased and no changes were observed in the content of caryophyllene oxide and β-elemene with increasing altitude. In general, the results showed that altitude is an important and influential factor affecting Inula helium's quantitative and qualitative yield.

Seed production is one of the key factors in the seed regeneration of plants and trees and is widely used in regeneration, forest development, afforestation and especially seedling production in nurseries. Therefore, it is very important to select quality and ripe seeds with suitable physical shape. The aim of this study was to investigate the effect of altitude factor on the physical properties of pistacia seeds in Sustan Reserve, which is one of the four pistacia reserves in West Azerbaijan Province. The reserve was divided into 4 altitude classes including 1515, 1615, 1715and 1815 meters above sea level. Also, in order to increase the altitude, the reserve area was divided into one-hectare sample plots (100 m * 100 m) In each sample piece, Three seed-giving trees including the diameter, the smallest diameter and a medium diameter were selected (Slope, direction and soil factor were equalized). A total of 60 trees were selected and 5 clusters from each tree were randomly collected in the north, south, east, west and center of the crown and the physical characteristics of the seeds included: cluster length, ‌ number of fruits per cluster, fruit length, fruit width, Fruit weight, grain weight and seedlessness percentage in each altitude class were evaluated. Data were analyzed using Excel and SPSS software and the means were compared and the analysis of variance was performed using F-test, Duncan multiple comparison test and Kruskal-Wallis test. The results showed that all traits except the percentage of seedless at different altitudes above s

This study aimed to investigate the effect of altitude on diversity and Species Importance Value (SIV) of herbaceous species in forests of Kabirkouh, Ilam province. For this purpose, an area of 300 ha was chosen from these forests. The area was divided in to three altitudinal classes (700-1000, 1000-1300, 1300-1600 m a.s.l.). 63 sampling plots were taken in the studied area using the minimal area method. In order to estimate herbaceous cover, the percentage of herbaceous species were recorded according to Van der Marel criterion. Species richness index (R=S), the Shannon- Wiener’s diversity and the Smith- Wilson’s evenness indices were used to calculate the herbaceous species diversity. Determination of correlation between biodiversity indices and altitude was done using Pearson’s correlation coefficient. The results of this study showed that the altitude had a significant effect on the diversity and richness of herbaceous species, and there was a negative correlation between these indices and altitude. The highest species diversity and richness index were in the middle altitudinal class. The results also indicated that altitude had no significant effect on the evenness of herbaceous species. In addition, the shape of the curve of Species Importance Value of herbaceous species in all three altitudinal classes was a lognormal distribution.

The study of flora characteristics and their relationship with ecological factors in habitats has a particular importance, especially in protected areas. This study aims to analyze chorological and endemism of the Central Alborz protected area flora. The study area is the slopes of Welwesht, Dahla, and Azadkouh heights in the protected area of Central Alborz, Mazandaran province. The total number of collected and identified taxa is 331, which belong to 197 genera and 46 families. During the floristic studies of the region, Nepeta azadkouhensis Saberamoli from Lamiaceae family was identified and introduced as a new species. About 49.25% of taxa are hemicryptophytes, 57.40% of all species belong to Irano-Turanian chorotype. Forty-six taxa, equal to 13.9% of all taxa, are endemic to Iran. Of these, 37 species, equal to 82.22% of endemic species, belong to the vegetation zone of Irano-Turanian. The habitat of mountain steppes, mainly with grasses and cushion-shaped plants with 24.47% of the total taxa, has the highest species richness. The results of the species richness study in the altitude classes of the endemic taxa showed that, in total, more than 70% of the taxa are located in medium to semi-high habitats. The study of the presence of endemic species in vegetation elements confirms the dominance of the Irano-Turanian vegetation zone in the region, with the significant presence and influence of European-Siberian elements.

Capers (Capparis spinosa) are one of the valuable medicinal plants that can grow in a wide range of ecological situations. In order to investigate the effect of climate on the physiological compounds of this plant, plant samples were collected in late summer with three replications from the mountainous areas of Amol city (Nemarestaq, Delarestaq and Behrestaq) at four altitudes with a difference of 150 meters (minimum altitude 850 meters). Some physiological traits of leaves and fruits were measured and analyzed by compound analysis in a completely randomized design. Data analysis showed that all the measured traits were affected by climate and were statistically significant, so that the highest amount of chlorophyll a, chlorophyll b, carotenoids, vitamin C, phenol, flavonoids, anthocyanins, antioxidants at an altitude of 1650 meters in Behrestagh region with 6.75, 10.56, 3.59, 15.60, 24.66 mg/g fresh weight, 4.51, 2.55 μmol/g fresh weight and 81.78% inhibition, respectively, and the lowest was observed at an altitude of 850 meters in Nemarstagh area. Regression slope also proved the significant relationship between traits and region and altitude, and antioxidant capacity which is the most important medicinal property of this plant, along with chlorophyll a, had the highest relationship (r² = 0.93). Also, the analysis of Pearson simple correlation coefficients showed a positive and significant effect between the traits. In general, with increasing altitude, an increase in the amount of measured physiological compounds that have medicinal effects was observed, so it is possible to develop the cultivation of some medicinal plants close to this family in the highlands.

Seed of 22 populations of Tanacetum (12 species and 7 subspecies) and seed of Pisum sativum, Petunia hybrid and Triticum aestivum as internal standards were selected and were caltivated under the same greenhouse conditions. Genome size (C-value, mass of DNA per haploid nucleus) was estimated by flow cytometry. Data from the study were analyzed by SPSS 16 software. The result revealed genome size is positively correlated with pollen morphometric, shape and colour of capitule, type of inflorecences and corology of species, but is negatively correlated with size of seed and environmental factors such as altitude and humidity of the habitat. The variation in the 2C value (mass of DNA per diploid nucleus) was high, with a range from 3.84 pg in Tanacetum parthenium (Tehran) to 24.12 pg in Tanacetum polycephalum subsp. farsicum. As wellas a 6.28-fold variation in 2C value and 2.73 fold variation in C value were found. Key words: Altitude , Genome size, Pollen grains, Morphology, Flow cytometry.

Mountains are unique ecosystems which are described by variety and complexity. Extreme changes in topography and climatic and biological gradients with seasonal and fragile contrasts are characteristic of these areas. With increasing pressure on wildlife species, highlands play the role as the last wildlife sanctuaries. Altitude plays a key role in the formation of these areas which influences other environmental factors either direct or indirect. The altitude constraint in the use of land has been an obstacle to the severe development and consequently manipulation of these areas. In order to investigate the displacement of species of protected areas in the province, the observation of 17 species of birds and mammals in the province was identified then, the resistance map was prepared using weighting to different heights. The least cost path and circuit cape methods as well as the metrics related to each of them, were used to model and analyze the wildlife movement pathway. According to theoretical results, 15 habitat corridors with a length of 1363 km were identified. Bisotoun wildlife refuge and Bozin and Merkhil no hunting areas play the most important role in establishing the territorial communications of protected areas. Based on the results of the least cost analysis, 26 corridors with a length of 4317 km were modeled. Utility and density metrics of using the corridors in the least cost method indicated that the most desirable corridor for the displacement of wildlife species along the paths of the Bisotoun, Paraw and Khorin mountains is located on the Shaho Mountain.

Environmental factors such as humidity and temperature varying at different altitudes of the forest and affect on plant distribution, species types and leaf morphology. Altitude is one of the important factors affecting environmental factors. In this study for evaluate the morphological changes of the leaf along the elevational gradient, five oak populations were surveyed in different altitudes of zagros forest in kermanshah province. At each altitude, five trees were selected and from each tree, 20 leaves were collected. Then in each population, leaves were mixed and fourteen leaf traits were measured. Results of duncanʼs analysis showed that there was a significant difference among five populations in all studied leaf characteristics and traits sush as area, perimeter, length, width, Ave Radial, Radial var, CMRV, S Factor, Width in X and Height in Y, had the highest values in high altitudes. two parameters of leaf area and perimeter with the highest amount of cumulative variance (67%) had the most role in grouping. Based on cluster analysis Five oak populations were divided into three groups and Population 2 and 3, as well as population 1 and 4, showed the most similar in morphological traits. The population 5 showed less similarity with populations 1 to 4 which this issue might demonstrate genetic diversity in this population.

Determining the response of plant species to environmental gradients is an important issue in the analyses of vegetation communities. The purpose of the present study was to investigate the most important environmental factors shaping the occurrence of Dactylis glomerata in Takab rangelands.

Eighty four plots (1m2) were placed randomsystematically along the azimuth of the studied area. In each plot, the presence of the species was recorded and one soil sample at the depth of 0–20 cm was collected. Some soil physical and chemical properties including soil moisture, texture, pH, electrical conductivity, organic carbon percentage, and the percentage of total nitrogen were measured in the laboratory. Data analysis was performed by Rver.3.0.2 statisti cal software. The binomial distribution of the Huisman – Olff Fresco (HOF) function was used to fit the curve of species response to environmental gradients.

The results demonstrated that the altitude variable is the most important environmental factor affect ing D. glomerata distribution. Moreover, the optimal ecological amount of this variable for D. glomerata is 2100 m above sea level. After altitude, slope (%), soil organic carbon (%), soil total nitrogen (%), and soil moisture content were the most effective factors on the distribution of D. glomerata.

In general, D. glomerata was more distributed in the lower slope of mountainous areas with high soil organic matter and moisture content.

To evaluate the quantitative and composition status of the trees regeneration in natural forest stands of Astara region, were studied the less disturbed areas in Astara (watershed 1). After selecting the study areaو sampling was done by systematic random method. Sample plots were circle shape with area of 0.1 ha. The relevant data were analyzed in the total altitude classes. The results demonstrated that sapling density of total species and the number of tree regeneration per hectare increased with increasing of altitude from sea level. The results also showed that there are significant correlation between the number of beech, hornbeam and mean total tree regeneration with altitude from sea level. The maximum and minimum number of regeneration were observed at the classes of "tree height

Teucriumpersicum Boiss.is an Iranian endemic plant belonging to the Lamiaceae family which has traditionally been used to relieve abdominal pains, there are 12 species in Iran. The bulks aromatic plants come from wild populations whose essential oils compositions as well as their biological properties are severely affected by the geographical location Therefore, the aim of the present work is to provide more information on the variation of essential oil composition of T. persicum collected from four different geographical regions in Fars province in 2014. These areas were darab-gardanebezan, Zireh-darab, Ghir-karizin, and Zakharoyeh with, 1500, 1400, 950 and 800 meters altitudes respectively. Sampling of aerial parts (flowers and leaves) of the plant was carried out at flowering stage and dried in room temperature and the essential oil was obtained by hydro distillation using Clevenger machine.The GC / MS device was used to identify essential oils. A total of 93 combinations were identified in the essential oil of T. percicum populations, in which the number and type of compounds in the essential oils of these populations is very different. The most essential oil composition of this plant was identified in the darab-gardanebezan (68 combinations) mountain range, while the highest Essential oil yield was observed in, Zakharoyeh (0.3%). The habitat of Zireh-darab with the highest percentage of alpha pinene, beta-pinene, limonene and valerianol has high quality essential oil and is the best site for T. percicum plant in this study. Alpha-pinene, beta-pinene, E caryophylline and caryophylloin oxide were important components of essential oil in all four regions.

Juniperus communis L. ssp. hemisphaerica is a dioeciously wild growing shrub, which is belonged to Cupressaceae family and could found in the Alborz Mountain in north of Iran. The essential oil of Juniper is used as anti-depressant, anti-rheumatic, anti-spasmodic, carminative, antidiabetic, appetizer and diuretic properties. In this research the effects of altitude on the quantitative and qualitative characteristics of the essential oil in different gender of this plant was investigated. The aerial part of different gender were harvested from two altitudes (2200 and 2700 m) in summer 2011. The essential oils were extracted by hydro distillation and were analyzed by GC and GC/MS. The results were showed that the foliage of male plants in both altitude contained higher oil content (2.74%-2.85%) than the female plants (2.20%-2.59%). The α-pinene and sabinene were the main components of essential oils in both foliages, but the highest amount of α-pinene (48.81%) and sabinene (44.47%) were observed in 2200 m in both foliages, respectively. Monoterpenes were the main compounds, which identified in these essential oils.