جستجوی مقالات مرتبط با کلیدواژه « gis » در نشریات گروه « جنگلداری »

Oak is a common and the most important species in Zagros forests of Iran. Zagros forests play a crucial and effective role in water supply, soil conservation and climate modification. Unfortunately, a significant part of those forests suffer from oak decline. Zagros forest covers almost 40% of Iran’s woodland which especially during the last two decades the population of oak trees (Quercus spp.) decreased mainly due to drought, diseases and insect pests. One of the most important pests in western oak forests is green oak leaf roller, Tortrix viridana L., (Lep.: Tortricidae) feed on oak leaves as the main host.  

This research aimed to assess and predict the degree of damage to the oak forests using remote sensing and GIS methods through regression analysis of the oak foliage remaining ratios of field plots with a vegetation indices of Sentinel-2 data during a year. Field monitoring carried on from April- 27-2020 to May-14-2020. For this purpose, in a two-kilometer-wide vector along the route from Sarovabad city to Bashmaq border, 100 sampling locations were randomly determined using GIS software. In each sampling location, four trees were selected in the four main geographical directions (in order to reduce the effect of directions on distribution of T. viridana population). Then, four branches (length about 100 cm) were randomly cut as a sampling unit, and the number of fifth instar larvae of T. viridana, were counted. The correlation between the number of T. viridana and elevation, slope, distance from the road, distance from the river, distance from residential areas, NDVI and solar radiation index were analyzed using Pearson's correlation test and multiple linear regression. Data normality was checked using the Kolmogorov-Smirnov statistical test. Data were analyzed using SPSS software (Version 26).

The results of Pearson's correlation analysis between the those variables and T. viridana population show the highest and lowest correlation of the T. viridana population with elevation (r= 0.651) and slope (r= -0.015), respectively. According to multiple linear regression, elevation had the highest correlation coefficient with T. viridana population density. In addition, solar radiation index, NDVI and distance from the river were ranked with strong to weak correlation, respectively. Results showed that, the relationship between slope and vegetation density is also significant (P= 0.032; r= 0.214). According to the distribution intensity map of the T. viridana, which was obtained using the multiple linear regression equation, it has been shown that the most distribution of the T. viridana was observed in the southwest of Sarovabad city. Clearly NDVI was convenient for separating different levels of damage.

It can be concluded that the population of T. viridana is obviously high at high altitude and in high tree densities. The results showed that the population density of T. viridana is higher wherever a dense vegetation was occurred. This research provided a feasible and quantitative method in the spatiotemporal prediction of green leaf roller occurrence by remote sensing and GIS. In conclusion, with the availability of population models, it is possible to limit the spread of T. viridana through earlier detection of pest incidence.

As one of the most important systems of human life, the forest has an undeniable place in ensuring the well-being and comfort of humans. Based on the forest strategy of Global Bank, it is mentioned that More than 1.6 billion People in the world depend on the forest in various ways to provide their livelihood. A common political debate about development and the environment is that the poor are both the cause and the victim of environmental destruction. The interpretation of this narrative for the forest shows it shows that the reduction of poverty can reduce the pressure on forest resources and the preservation and development of forest resources can help reduce poverty. Accordingly, in this research, the condition of the forests of Shafarood watershed in Gilan province for The implementation of two income-generating activities of apiculture and aquaculture, in order to create economic prosperity for rural communities and other beneficiaries dependent on the forests of this area, and at the same time preserving these forests based on the prioritization of criteria and sub criteria. Shafarood basin with an area of 36,657 hectares is located in the west of Gilan province, between the cities of Rezvanshahr and Pare-Sar and east of Talash highlands. In order to determine the appropriate economic use of rural communities in Shafarood forest and to identify the main criteria for each of the desired economic activities, observation, interview and questionnaire techniques were used from 55 experts which are selected randomly. In the current research, a questionnaire was used in three stages to complete the process, and the data obtained from the questionnaires related to criteria and sub-criteria were analyzed by the method of pairwise comparisons, which were use the GIS software in order to obtain the optimal spatial map of each economic activity. According to the results, in the apiculture, the criteria of plant diversity, temperature, and the number of trees per hectare, and in the aquaculture, the criteria of distance from the river, distance from the spring, and temperature were recognized as the most important factors for the development of these chains. Based on the opinion of experts for apiculture, the sub-criteria of humid climate with a final score of 0.03 had the highest score while the high investment capacity and the distance from dirt roads, both with a final score of 0.24 0 were also important. For the aquaculture, humid climate sub-criteria with a final score of 0.03 was the most important and the high investment capacity with a final score of 0.029 and a distance of less than 500 meters from the river with a final score of 0.026 were in the second and third place. The results also showed that 22.13% of the entire area (8063.31 hectares) and 14.41% of the entire area (5249.9 hectares) can be used for apiculture and aquaculture, respectively. The results can be used for economic development in Shafarood forests. According to the findings of this research in relation to the effective criteria and also the rural population present in this watershed, a relatively suitable area for each economic activity is determined. It is necessary for the forest managers to develop the rural communities based on finding the other sources of income from forest which should be paid attention to it.

In this study, we investigated the effects of forest operation on runoff and sediment using small-scale plots. The runoff and sediment samples were collected from 36 sample plots with dimensions of one by two meters in different areas of the operation. We used the Multi-Layer Perceptron (MLP) for modeling, with 65% of the data for training, 10% for validation, and 25% for testing. We evaluated the accuracy of the model using the coefficient of determination (R²), root mean square error (RMSE), and mean absolute error (MAE), and compared our results with optimized models obtained through trial and error. We collected information and produced runoff and sediment maps using GIS. Our results showed that the most important factors affecting runoff production were soil bulk density, rainfall intensity, slope, rainfall values, percentage of grass cover, and canopy cover percentage. For sediment, the most important factors were rainfall intensity, soil bulk density, slope percentage, and surface cover percentage. The MSE and R values for runoff modeling were 0.009 and 0.9 in the training stage and 0.01 and 0.82 in the test stage, respectively. For sediment modeling, the MSE and R values were 0.01 and 0.86 in the training stage and 4.3 and 0.8 in the test stage, respectively. Our results showed that neural networks have high capability in modeling runoff and sediment in forest lands. We also conducted an overlap analysis to measure the accuracy, precision, and efficiency of the results and methods presented in our study. Therefore, the proposed model can be used to combine ANN and GIS in the simulation and modeling of runoff and sediment in forest areas."

Forests as a renewable resource play an important role in the economic and social activities of the society. In the principled exploitation of the forests of northern Iran, the existence of a suitable road network along with skid trails the most fundamental role. Skid trails in the forest are one of the most difficult and costly operations. The purpose of this study is to design the proposed Skid Trails Planning in the forest using AHP and GIS for various operations.

For this purpose, the parcels 18 and 19 of district 4, part 2 of Neka Zalemarud with an area measuring 97 hectares have been selected. According to effective factors in skid trail planning such as slope, soil, geology, stand per hectare, streams, aspect, forest type, elite trees, and altitude, we have attempted to design a questionnaire and filled by some experts. These factors were weighted in Export Choice (EC) software via the pair-wise method. Finally, the status of the designed skid road and the existing skid road were compared. Then, on the map, the ability to pass lands in Arc view environment was designed using PEEGER software, three options. Finally, the specifications of the proposed routes were compared with the existing route. The Chi-square test was used for statistical comparison between the most appropriate option and the available path.

Analysis of different layers based on the opinion of experts, showed that the longitudinal slope with a relative weight of 0.366 has the highest score, followed by the waterway 0.115 and finally the height above sea level with a relative weight of 0.026 has the lowest score. . The results of evaluating the existing routes and proposed variants on the land passability map showed that the percentage of passing the existing route length over the area with suitable power is less than the proposed variants (22.87) and the percentage of crossing the existing route on the area with Inadequate power is higher than the designed variants (24/99).

The results of the Chi-square test showed that the proposed routes were significantly (at 95% level) better than the existing route in terms of crossing suitable areas (p = 0.0001). Therefore, according to the results, if the percentage of the desired longitudinal slope is reduced; it is suggested to consider a longer route because, in such a long route, the topography cannot be shown precision.

With the development of urbanization, humans gradually shifted away from nature and, to the same extent and the environmental, physical and spiritual needs of man to the green space are increased. The objective of this study is to locate areas prone to developing urban forestry in the metropolis of Tabriz, from the point of view of the necessity of development and the need of citizens (not ecologically) and present developmental solutions. 14 criteria were chosen as standardized in format of Raster maps based on previous research and expert opinions. The pair comparison table comprised the criteria and the weight and importance of each criterion were calculated. After completing the multi-criteria evaluation process, the final map of the priority areas for the development of urban forestry was produced and the area and the percentage of the first, second and third priorities were calculated. Accordingly, 29.8% of the Tabriz area has the highest priority for the development of green space. In the next step, by overlaying the finalized map with the current land use map, the area and percentage of each of the first, second and third priorities located in the current land use classes were obtained. Comparison of these maps showed that 50% of the priority areas for urban forest development, were located in the existing residential areas, 39% were in vacant fields, 9.5% were in agricultural lands and gardens, and 1.5% were in the current green space. These results indicate excessive and unbalanced construction accumulation in most municipality districts of Tabriz. Therefore the general policy in these areas should be stopping new construction and prioritize changing the worn out texture of the city to green space.

Forest fire management has important role in fire prevention and effects. The aim of this study was applied of Geographical Information System(GIS) and Artificial Neural Network (ANN) to determine forest fire criteria in Golestan province. The influence of each parameter on fire ignition was determined by collecting of 37 sample from burned area and 37 sample from not burned area. For formation network between criteria and fire occurrence used of Multilayer perceptron (MLP) with Hyperbolic Pattern Algorithms. the results shown raining and distance from road had must influence on forest fire ignition. Validation test showed that the best network obtained in run 4 and epoch 450 with 0.0038 Final Mean Square Error (FMSE) in training steps. Also, about 95 percent of area burned and 84 of unburned areas has been properly classified. Finally, forest fire hazard maps was obtained based on each criteria weights. Result showed this network with 2 hidden layer and 12 neuron in each of them has best accuracy, and correlation coefficient (R) was 0.80.

Forest roads are constructed to facilitate forest protection, reforestation, logging operations and maximizing the value of forest products. Therefore forest roads are key infrastructures in the development of the region. This study aims to plan forest road network using artificial neural network and GIS regarding forest road technical principles. First the criteria were chosen using Delphi method and then they were weighted regarding their importance in road planning. After that the criteria were combined with corresponding weighs to achieve suitability map based on the degree of suitability for road allocation. Value and coordinates of each pixel were extracted by ENVI software and were normalized in the range of 0-1 for modeling by MATLAB software. In this study two neural networks were used for modeling, including multilayer perceptron (MLP) and radial-bases functions (RBF). The neural networks estimated suitability of different pixels in other districts based on the Patom district results. Using an ArcView GIS extension, PEGGER, two forest road networks were planned. The results showed that MLP provides better ability for estimating suitability of pixels for road passage in comparison with RBF with the R2 of 0.994. A linear regression was also used to compare the results of the proposed neural networks. The results revealed that neural network improves the results in comparison with the linear regression and results showed that the second road alternative was optimum network with regard to the unit cost

This study investigates the capability of frequency ratio and an ensemble method of frequency ratio with Shannon’s entropy to produce a reliable map of wildfire susceptibility for Chaharmahal and Bakhtiari province, Iran. At first, the fire locations were identified in the study area from historical archives and field surveys. Ninety two cases (70%) out of 132 detected fire locations were randomly selected for modeling, and the remaining 40 (30 %) cases were used for the validation. Thirteen fire conditioning factors representing topography, climate, and human activities of the study area were extracted from the spatial database. Using the frequency ratio and the ensemble model, the relationship between the conditioning factors and fire locations were explored. The results were then used to produce distribution maps of wildfire hazard. The verification analysis using Receiver Operating Characteristic (ROC) curves and the Areas Under the Curve (AUC) revealed that the ensemble model with the capability of computing the weights of factors and their categories is more efficient than frequency ratio. The success and prediction rates for the frequency ratio and ensemble model were found to be 79.2 and 75.72%, and 85.16 and 82.92%, respectively. Further, the results suggest that more than one-third of the study area falls into the high and very high hazard classes, and the conditioning factors of land use, soil types, and distance from roads play major roles in fire occurrence and distribution in the study area.

In this recent years with the development of natural sciences, the importance of biodiversity is Revealed In different fields and the objectives of forest management are foccosed on biodiversity. So that nowadays conservation of biodiversity is considered as the most important issues in sustainable forest management. The importance of northern forests of Iran in aspect of conservation of genetic resources, and some plant species that are unique to this region is common clear fo all and And its vital role in many aspects such as economic, social, environmental balance, ecosystems stabilization and conservation has attracted the manager attention at the regional and local levels. One of the most important problems of that forests is Destruction Caused by natural and anthropogenic factors in recent decades, has faced them with a crisis situation. Lately, the Buxus Blight is encountered as an important problem in the northern forests. According to the importance of Buxus Hyrcana in aspect of biodiversity Iranian Forest managers are trying to identify its factors and spatial patterns.

The main goal of this study is investigation on spatial distribution of the Buxus Blight in relation to primary and secondary topography characteristics and distance from river and roads using terrain analysis and GIS.A 200×500 meters random systematic sampling network with 0.1 ha sample area was designed in GIS and applied on Khiboos & Anjilsi Forest protected Area. The location of diseased trees were registered using GPS in each sample and was imported to GIS. The digital elevation model (DEM) of the study area was generated using the interpolating of contour lines from 1:25000 topography map and the primary and secondary topography characteristics and distance from river and roads were produced using terrain analysis and GIS. The digital values of location of diseased trees were extracted on produced maps. The impact of selected factors on the tree crown dieback was assessed using relative effect (RE) method and principal component analysis (PCA).

The results showed that the north aspect, 400-600 meter mean sea level altitude, the 30-40 percent slop, the 0-50 meters distance from rivers, the 300-400 meters distance from roads, the shaded relief of 0.8-1, solar radiation of 0-250 and wetness of 17/5-20,were more effective on the Buxus Blight. The results of PCA analysis also showed that four factors of Aspect shaded relief wetness and distance from river with attending on four axes and 72 percent variances have been effective on Buxus Blight.

According to the results of this research it can be stated that damages caused by boxwood blight are heavily affected by some environmental factors such as light and humidity and landform factors because of receving of different amount of light and humidity have an important role in severity of that disease

This study aims at identifying the suitable areas for ecotourism using geographic information system (GIS) and analytical hierarchy process (AHP) in experimental and educational Kheyroud forest, Nowshar, Mazandaran province. The evaluation process was conducted based on three groups including ecological, infrastructural, and socio-economic criteria. Then, the indicators of each main groups were determined. The indicator maps of slope, elevation, aspect, temperature, soil, water resources, landscape, wildlife, vegetation cover (density and type), cow-pens, forestry plan and road were generated in geographical information system environment. The Analytical Hierarchy Process was used for weight determination of indicators. Finally, based on the weighted linear combination method, weighted layers of indicators were integrated in GIS environment and ecotourism suitability map was created. According to the results, slope and water resources indicators and soil and cowspens indicators showed the highest and lowest weights, respectively. In addition, the results of evaluation revealed that 0.17, 38.15, and 61.88 percent of the area have high, medium, and low suitability for ecotourism purposes, respectively. According to the ecological indicators and the development of infrastructural and socio-economic criteria, there is an extensive potential for ecotourism development in the Kheyroud forest

Due to the lack of comprehensive planning at the national level¡ urban services uses among green space have encountered problems such as deficiency of green space per capita¡ inappropriate distribution and location and lack of prediction of this spaces in cities. In this study¡ for the first part: Using GIS capabilities¡ arboreal green spaces per capita¡ including parks and gardens planting trees and tree stands can be used for public¡ in different regions of Mashhad¡ evaluated using satellite images and regions were prioritized in terms of per capita. The results showed that region 3 has the lowest arboreal green space per capita. In the second part: Locating of urban forest park¡ with considering its criteria on aspects of recreational¡ ecological and structure were investigated. In the first layer data maps were produced¡ then standardized using various fuzzy functions. Then the standardized maps multiples own weights got from AHP¡ and were combined using WLC method. Result maps¡ showed suitability of Mashhad region 3 lands and the most appropriate sites for creating of urban forest parks. The results showed that barren lands and agricultural lands¡ respectively¡ have much suitability compared to other land use because of the ease of conversion to urban forest parks. Also areas that are closer to the city center¡ have a high suitability for creating an urban forest parks¡ because of the proximity of residential¡ education¡ tourism and recreation uses and also the ability to create boundaries and privacy¡ and improve the quality of urban areas and proximity to air and noise pollution sources. From the results of this study can be used future projects and plans related to the construction of urban green space according to the criteria and area potential.

Forest fires frequently cause disturbances in vegetation cover worldwide. The aim of this study was to 1) assess the effects of spatial indicators on forest fire ignition and 2) to map the susceptibility to forest fires using Analectic Hierarchical Process (AHP) and Geographical Information System (GIS) in a portion of southern Zagros forests in Khuzestan province. Analysis of topography, land use, climate, habitat sensitivity as well as fuel index maps showed that 15.6, 59.5, 10.7, 20.6, and 35.7 percentages of the area is of very high to high potentials for forest fire ignition, respectively. Furthermore, the fire risk map indicated 8.6 % of this region to be very highly prone to wildfire. The results of cross-validation revealed that 9.6 and 67.3 percentages of the previous forest fires occurred in classes featuring very high and high fire vulnerability. In addition, GIS and AHP method were found to offer appropriate and efficient tools for management and mapping of forest fires in the Zagros forests of Iran.

Forest roads are basic infrastructures for management of forested areas. Sustainable management of roads depends on regular and timely forest road maintenance. Road inventory is as an important tool to recognize the needs of roads and do corresponding correction operations. GIS can be a powerful tool for acquirement, analysis and management of data in road management. The purpose of this study was to obtain the required information for road management in Kaleibarchay watershed, Arasbaran region, to provide practical maintenance and monitoring solutions. To do this, 131 samples were selected and for each sample some data such as road gradient, template, problems of surfacing and slope stability were collected. Then spatial data and corresponding database were developed in ArcGIS and were compared to standard values. According to the results cross-slope has the highest consistency with standard values. 25.19% of the road length was without any sign of surfacing problems. Among surfacing problems rutting has the highest and pothole has the lowest abundance and cut slope had more stability problems than fill slope. In order to better management of drainage system, we suggested some places for new cross drain including culverts and fords. The results of this research showed the potential application GIS for forest roads management.

A study was conducted to evaluate fire risk using environmental- and human-induced factors in‌ District Three of Neka-Zalemroud forests. For this purpose, a range of effective sub-criteria including physiographic, biological, climatic and human variables were applied. The historical fire map‌‌‌ in study area was additionally used. It was overlaid on the spatial map of each sub-criterion to explore the correlation of the weighted high-risk classes with the historical fire occurrences. Fire risk potential map was provided based on weighted overlay of all effective sub-criteria in five classes. The historical fire map was consequently overlaid on fire risk potential map. Results showed that vegetation type and density, distance from river and the averaged relative annual humidity were associated with the highest effects in fire occurrence. Results also demonstrated the agreement of high-risk areas in the potential fire risk map with the historical fires, which supports the high validity of the applied method to assess the fire risk across the study area.

Forest fires in the Iran and particularly in the northern forests had destructive effects on the physiognomy of these forests. Recognition، prevention and controlling the Scio-economic destroys caused by natural hazard is one of the main objectives of applied and educational organizations. One of the methods for prevention on forest fires is mapping the probability risk zones. In this study، map of fire probability risk for Golestan national park was prepared using regression logistic method and GIS. The effective factors on fires including climate، topography، vegetation and human factors were prepared in the GIS environment by different methods and sources. The occurred forest fires map was gathered and generated as a Boolean map. The logistic regression modelling was done using effective factors as independent variables and the occurred forest fire map as dependent variable. The obtained PseudoR²= 0. 3121 and ROC = 0. 9132 from model indicate that regression logistic could modeled forest fire probabilities on the study area. The probability fire map was classified to four low، medium، high and sever dangerous classes. The obtained forest fire probability map was assessed using the some unused occurred fire points. The assessment results showed that more of occurred forest fire points were in the medium and high dangerous classes.

Undoubtedly, Khorram-Abad Country has been considered as one of the most beautiful, scenic and pleasant weather areas of Iran because of many natural, cultural, historical, etc attractions. Despite the great potential for ecotourism development in this country, it has not been implemented a good plan for ecotourism development in this area. This study intends to identify the effective criteria and sub-criteria in ecotourism evaluation with respect to the area conditions and suggest the suitable areas for ecotourism development. For this regard Geographic Information System (GIS) and Analytical Hierarchy Process (AHP) have been used. At the first step, effective criteria and sub-criteria in the evaluation process determined and the weight of each criterion and sub-criterion determined using the Delphi technique and expert's knowledge. Then, the required maps were prepared. After that, with the integration of maps and their corresponding weights the capability map for ecotourism was prepared. The results showed that 7.80, 60.75, 46.37 and 5.50 percent of the study area has excellent, good, moderate and poor potential respectively and 2.35 percent of the area is not suitable for ecotourism at all.

The aim of the this study was to evaluate reference evapotranspiration (ET0) and relative humidity (RH) impacts on forest fire occurrences in Zagros forests of western Iran, Khuzestan province. Monthly mean meteorological data obtained from five meteorological stations were employed for mapping the ET0 and RH. When ET0 was taken into account, 16.8 % and 21.7 % of this region were classified as high and very high risk classes, respectively while the map of RH indicated that 44.5 % of the study area was in the high risk class of forest fire. Cross-validation analysis based on ET0 revealed that the maximum number of fire occurrence per hectare were in the very low and moderate classes of fire risks. However, for RH the maximum number was observed in the very high risk class (0.003 numbers per hectare). In compare to ET0, RH is preferable for understanding the effects of forest fire occurrence as well as for the forest fire mapping.

Recreation planning is not only as a tools for enhancing of socio-economy levels of the people but because of its conservational functions can provide a dynamic conditions for conservation of natural resources. With respect to this point that the first step in recreation planning like planning for any activity is the evaluation of land potential for that activity. The aim of this study was to evaluate the potential of ecotourism of Babolrood watershed in Mazandaran province by using of analytical hierarchy process (AHP) and geographical information system (GIS). For this regard، firstly the most important effective criteria and sub-criteria in evaluating of the potential for recreation in the study area were determined by using prior researches، conditions of study area and expert knowledge. After that، some questionnaires were provided and between different experts were distributed. The weight of criteria in each questionnaire was calculated and then the averaged weights were estimated. With applying of AHP method and Expert Choice software the final weight for each criteria and sub-criteria was determined. After that، the needed maps for this evaluation were provided in GIS environment. At the end، with help of Weighted Linear Combination (WLC) technique the final potential map for the ecotourism development of region was provided. The results showed that 19/33 percent of study area has a high potential and 52/81 percent has a good potential for ecotourism. In addition، 23/19 percent has an average potential، 1/84 percent has a weak potential and 2/82 percent is not suitable for recreation land use.

This research was carried out to study the relationship of physiographic، climatic and human factors with the spatial distribution of Quercus brantii – Pistacia atlantica type. Quercus brantii – Pistacia atlantica type map was prepared based on existing maps and edited by field surveying in 11336 hectares of Sarvabad forests. Physiographic attribute (elevation، slope، aspect and distance from streams) and human factor map (distance from residential) were derived from the topographic and landuse maps، respectively. Climate factors maps (temperature and rain) were produced based on the records of 5 years meteorological bureau. Logistic Regression was used to select the most important effective factors in presence of Q. brantii – P. atlantica type and to model it. The results showed that the spatial distribution of Q. brantii – P. atlantica type is a function of altitude، aspect، slope، distance from streams and rainfall. Increasing of altitude، moving from wet slopes to dry slopes، reducing the distance from streams and reducing of rainfall are caused more presence of Q. brantii – P. atlantica type. According to regression analysis، some factors such as distance from residential and temperature are less effective than other studied factors on the presence of Q brantii – P. atlantica type. The results showed that 95% of Q. brantii – P. atlantica type are in the class above 50% of probability.

This research was carried out to compare two oak (Quercus brantii) stands (healthy and affected by oak decline) in respect to characteristics of competitive environments in Shalam Forest، located at north of Ilam province of Iran. The study area was divided into 20 topographical homogeneous units، using GIS method. Considering the dieback rate at the units، five homogeneous units with different dieback rates were selected. After that، six transects (100 m. length) were allocated at each of the units and five points were laid on them at 25 m. intervals، using the systematic random statistical method. The two closest dead and alive trees to the points were identified. Finally، some characteristics of the focal trees around the two selected trees were measured and recorded، including their distance to the focal trees، species، crown diameter and total height. Competitive condition of the focal alive and dead trees in the stands was computed by Hegyi index. The data were analyzed، using ANOVA and t-test statistical methods. Results showed that there was significant difference between the homogeneous units in respect to the tree''s competition rate. According to the t-test results، competition rate of the dry and almost dry trees was greater than that of the healthy or less dried trees. The lowest and the greatest tree competition rates were found in the homogenous units with lowest and greatest crown dieback rate، respectively. The focal dieback trees had lower crown diameter، total height and distance to the neighboring trees in comparison to the focal healthy trees، whereas the neighboring trees to the focal dieback trees had greater crown diameter، total height and density. It might be concluded that tree''s competition rate has direct correlation with stand or tree groups density which varies، depends on available soil moisture content and competitive stress at different parts of the stand. The results of this research can highlight importance of tree competition، dependant on stand density as a predisposing factor of oak trees mortality at drought conditions، occurred at recent years and can be useful for rehabilitation management of the oak forests under dieback condition.