جستجوی مقالات مرتبط با کلیدواژه « middle zagros » در نشریات گروه « کشاورزی »

Sustainable management and fundamental planning of forest resources require efficient and high-quality information about the current and future states of forests. Investigating the current and future states of forest stands, describing the structure of the forest stand, and the response of the stand to tending operations are among the capabilities of statistical distributions in forest management. Frequency distribution modeling is the distribution of people in a population in different classes. Since natural phenomena include continuous and discrete types, their distribution will also be different and diverse. The use of statistical distributions in the forest has a long history, and some researchers have considered its history as long as two centuries. Zagros forests, as one of the most important vegetation areas of Iran, have a special importance from the socioeconomic and ecological points of view. The dominant species of these forests is the Iranian oak (Quercus brantii Lindl). According to geographical and environmental conditions, this species has various habitats in the vegetation zone of the middle Zagros. It is expected that this species has different probability distribution functions in different habitats. Therefore, the probability distribution functions of the characteristic height in habitats with different vegetative structures of Iranian oak in the forests of Khorramabad city were investigated in this research to select the best models in different habitats. This study also seeks to provide useful information on the authority of forest managers and planners to preserve and improve these valuable forests.

To carry out this research, two areas with different structures, including coppice with standard (Sefidkoh area) and standard with coppice (Qala-Gol area) were determined in the forests of Khorram Abad city through numerous excursions in the forest. A forest stand with an area of approximately 3 ha was selected in each of these areas. This forest stand was chosen in such a way to represent the forests of the region. The subsoil was semi-deep and north direction in the Qala-Gol forest stand at an altitude of 1850 m above sea level and with an average slope of 20%. In the SefidKoh forest stand, the subsoil was semi-deep and located in the north direction at an altitude of 1900 m from sea level with an average slope of 30%. In each of these two selected forest stands, the height of all Iranian oak trees, with a height of > 1.5 m, was counted 100%. In total, the heights of 458 and 348 Iranian oak trees were measured in the two SefidKoh and Qala-Gol regions, respectively. A TruPulse 360 laser device was used to measure the height of trees. To investigate the distribution of height classes, the most widely used continuous probability distribution models in biological research were used due to the continuousness of the height variable, including two-parameter Weibull, two-parameter gamma, normal, log-normal, beta, and Johnson. The goodness of fit of the data was also examined using the Anderson-Darling test, which has a higher power than other tests. Easy Fit 5.6 software was used to analyze all data and draw graphs.

The statistical errors were 4.45% and 2.82% in the Sefidkoh and Qala-Gol regions, respectively. The average height of trees was 6.76 m in the Sefidkoh region (between 1.8 and 18 m) compared to that of 7.54 m (between 1.53 and 14.04 m) measured in the Qala-Gol area. The values of skewness and Kurtosis were positive in the two forest areas, with higher values in the Sefidkouh region than in the Qala-Gol area, indicating the concentration of data in lower-height classes in the Sefidkouh region. The results of Anderson-Darling's goodness of fit test in the Sefidkoh area (coppice with standard) showed that the most suitable probability distribution functions (with a 5% error level) for modeling the distribution of trees in height classes were Johnson sb and beta, respectively. In the Qala-Gol region (standard with coppice), the most appropriate distribution functions were identified as beta and normal, respectively.

  The results of this research show that the forest has an uneven-aged structure in the areas where the oak forest has a coppice with standard form, according to the form of distribution (decreasing distribution). In contrast, the forest has moved toward a single-stemmed and even-aged forest in areas where the forest form is standard with coppice. This is mainly caused by the destruction through grazing, the cutting of branches for livestock and fuel consumption, and the indiscriminate use of byproducts that have occurred in this region. In the Sefidkoh region, the effects of destruction and less human intervention were observed at the regional level in field observations. According to the shape of the distributions obtained in the two sites, the vegetative forms of the trees affected the distribution functions of their heights, which can provide useful information for managers, planners, and researchers to maintain and control these valuable forests.

This study aimed to evaluate the structural characteristics of natural forests and providing the possibility of studying the changes in the structural characteristics of these stands over time, in order to plan and manage the forest in the Tang Dalab To achieve this, all trees were calipered in two one-hectare plots. Additionally, the structural characteristics were measured using the nearest neighbor’s method. To measure several indices like nearest neighbor distance index (density of trees), uniform angle index Clark and Evans index (variety of location), Mingling index (species mixture), diameter and canopy differentiation indices (dimensional differences of trees), and complex structural diversity index (tree diversity) were used. The results of uniform angle (south site 0.44 and north site 0.48) and Clark and Evans indices (Southern aspect 1/07 and Northern aspect 1/09)indicated a random spatial pattern of trees. According to the Mingling index, the northern aspect has relatively moderate mixing (0.31) and no mixing (0) in the pure southern aspect). The mean distance to the neighbors was 8.12 m in the northern stand and 5.81 in the southern aspect. The results of the diameter and canopy differentiation index indicated a low difference in diameter (0.24) and canopy (0.24) in the southern aspect an average difference in diameter differentiation (0.41) and a high difference in canopy differentiation (0.51) in the northern aspect complex structural diversity index, indicated more diversity in the northern aspect (0.38) compared to the southern aspect (0.18). The indicators used in this research can be used to describe the structure and ecological characteristics of different tree species in order to increase ecosystem stability and planning to create heterogeneity in the structure of the stand and help forest managers in planning and making appropriate decisions. However, the effectiveness of these indicators in some situations is doubted by some researchers.

Forest management achieves its management goals by considering the natural state of the forest and having enough knowledge in relation to ecological characteristics of forest species and the current state of the forest structure and monitoring changes resulting from management activities. This research was carried out with the aim of knowing the existing structural situation in Tang Dalab forest area, in two Aspect direction, northern and southern.

In the center of two northern and southern sites, a square sample plot of one hectare (dimensions 100 x 100 meters) was permanently selected and planted. All trees and Coppice shoots located in this area were numbered and specified and the structural variables of all the trees in the sample plot were measured. To compare the average of the investigated variables in both sites, after testing the homogeneity of variances and the normality of the distribution of variables, t-student test was used

The results showed that the southern stand with a density of 72 Persian oak species (Quercus brantii Lindl) per hectare was completely seedling and its forest type is Quercus brantii Lindl while the northern stand with a density of 57 trees per hectare, 82% of its seedling and its forest type was Q. brantii - C. azarolus. The results of the T-test showed that all the studied variables have a significant difference between the southern stand and the northern stand at the probability level of 1% The average diameter at root collar (DRC), diameter at 0.5m height, and diameter breast height (DBH) of trees in the southern stand were more than the northern stand. The distribution of trees in the diameter classes of the southern stand, showed that this stand has an irregularly even-aged structure. The chart of diameter distribution of this stand states that there was no regeneration in the past years in the northern stand, in addition to coppice and young Persian oak trees, in the lower diameter classes, a number of young trees of other species with small diameters were seen. The height distribution diagram of trees in the southern stand showed that the largest number of trees are in the middle of the diagram and in the height classes of 5 to 11 meters. In the northern stand, coppice trees were present in the lower height classes (less than 3 meters). While more than 80% of seedling trees have a height between 6 and 11 meters. The results of the investigation of the basal area diameter at 0.5m of the trees in both stands showed that This variable in the southern stand (26.41 square meters) due to the presence of seedling trees and higher density, it was about More than three times the northern stand (7.48 square meters).

The superiority of the southern group over the northern group showed that the aspect has a major influence on the vegetation and forest structure. in sustainable forest management planning, while monitoring the structure of forest stands during periods of time, at least ten years, it is necessary to pay special attention to the different conditions of aspect in order to preserve, revive and develop these forests.

Changes in vegetation and land use have been unprincipled on the one hand, and the occurrence of tree decay in the last decade, on the other hand, has put additional pressure on the forests of the Zagros, causing significant significant drying of these forests in particular. It is located in Ilam province. Since awareness of the extent and location of deforestation and spatial distribution of areas at risk of destruction and prevention of this growing trend is the concern of planners and managers of the natural resources sector, the need for sustainable management of these valuable resources is easy access to information and data. The day is high. Therefore, the present study aimed to investigate the distribution of oak tree drying zones in physiographic units (slope, slope direction and elevation classes) as well as land use using geographical information system in this province.

In this study, first, using Alos and Srtm elevation models, in the GIS environment, slope information layers were extracted for slope and elevation classes. Then, based on satellite images and field control, the land use layer of the province was prepared. Also, using the GPS device, the position of the dried oak trees was determined and the relevant dotted layer was prepared. Then, by combining the prepared information layers (slope, slope direction, height floors and land use) with the location layer of dried oak areas, the frequency of tree drought zones of oak forests in physiographic and land use units is determined and examined. Took

According to the results, the drought rate of trees in topographic units (slope, slope direction and elevation classes) extracted from two models is also 12 meters and Srtm is 50 meters. Percentage (30%). 18% is for the northeast slope and 47% is for the 2000-1500 m high floor. Also, according to the Srtm model, the highest frequency of dried oak areas is related to the slope class of 10-20% (30%), 20% is related to the northern slope direction and 47% is related to the altitude of 2000-1500 meters. In terms of land units, most of the dried areas of oak trees are located in mountainous areas, hills, pebbled areas and plateaus, respectively.

In general, there is no difference between the percentage distribution of oak drying with slope classes in the two models studied. However, there are slight differences in the height of the floor and the direction of the slope in both models. In terms of forest use, the highest frequency of oak drying is in low (36.5%), medium (33.9%) and high (4.4%) classes, respectively.

Distinguishing soil surface horizon and its thickness is possible through soil survey and drilling. This requires budget, time, and skilled persons; therefore, using predicting methods as a solution for simple determination of soil characteristics has gained much importance in recent years. This work considers employing stepwise multiple linear regression statistical approach in order to propose a suitable model to predicate soil surface horizon thickness (SSHT) from topographic attributes according to establishment of soil and landscape characteristics relationships. To fulfill the goals of this study, data of primary and secondary topographic features of the Rimeleh sub-catchment located in Lorestan Province of Iran were derived from a Digital Elevation Model (DEM) and, the SSHT data yielded from soil surveys at 191 sampling points distributed in the study area in a systematically randomized manner. The SPSS 19 package was used to clarify statistical characteristics of gathered SSHT topographic data and test the fitted model considerations. The fitted model for the gathered data was Athick = 39.596 – 0.012E – 0.152S + 0.008AS.  The determination coefficient of the model was computed as 0.54. It is clear that the model fitted to the data has highly significant negative correlation with slope percent (S) and elevation (E) (P≤0.01) and a significant positive correlation with aspect (AS) (P≤0.05). Our investigation demonstrated that the fitted model to the scatter plot of observed data values versus predicted values has a determination coefficient of 0.54, which indicates the explanatory power of the model. Other topographic attributes affected the SSHT but their effects were not significant statistically. Therefore, they were not included in the model.

Oak decline is an eminent factor, which has a significant role in degradation and change in Zagros forests. The goal of present study was to assess the crown surface area of oak trees in Sarableh forests, Ilam province. For this purpose, permanent sample plots were used. Eighty sample plots with 10 Ar area were applied based on systematic-random method in a 150×200 survey network in 120 ha. The crown diameters and oak decline were measured. Oak decline was classified in five classes (very high, high, medium, no decline). The inventory was conducted in 2012 and 2014. The Mann-Whitney test was used to compare the oak decline in two inventory times. The results showed that the trees in very high and high decline classes (total of two classes) were 13.6% in 2012 and it is increased to 25.4% in 2014 (to be an 11.8% increase). The changes in forest decline were significant at decline classes (P≤0.01). The highest oak decline was observed in two m2 crown area and the maximum healthy trees were found in 14 m2 crown area. Our result revealed that trees with small crown area are more engaged by forest decline. In order to managing the forest engaging to oak decline in Ilam province and the rehabilitation of these forests , it is recommended the trees with small crown area (up to seven m2) should be more considered in terms of forest rehabilitation and tending.

According to the importance of Zagros forests and their sustainability, it is necessary to introduce sustainability management indicators being appropriate to these forests. For this purpose, forests of Firoozabad district belonging to Kermanshah were selected. The study area was screened and analyzed by DPSIR method to obtain a complete understanding of the relationship between phenomena and subjects. Then, based on the TOP Down method, the series of criteria and markers in different regions of the world were investigated. Indicator Reporting on the Integration of Environmental Concerns into Agricultural Policy (IRENA) was used to design the criteria and markers for sustainable management of Zagros forests. The initial list of markers and criteria was prepared by local stakeholders (A total of 30 people) using Likert scale. After calculating the mean and relative weight of scores, the final list of criteria and markers was prepared. The results of DPSIR process showed that the most important driving forces in the studied area were: poverty, inadequate job opportunities and loss of access to new knowledge and technologies. In our study, 5 criteria and 30 markers were introduced. Results showed the most important and the least important criteria in study area were legal and customary frameworks for forest management (with relative weight of 0.819) and extent and area percent of regional ecosystems (with relative weight of 0.65). The most important markers of the 5th criteria (the most important criteria) were the existence of solutions for eliminating disparities between farmers regarding grazing livestock, harvesting non-wood products and the rate of compliance with local customs in the exploitation of land and natural resources in the area.

Determination of soil depth and its variations is possible through soil survey and drilling. This requires budget, time, and skilled personnel. Soil – landscape relationships approach makes it possible to develop the soil depth predictor model from topographic attributes by using multiple linear regression statistic method. In this research, primary and secondary topographic attributes of the Rimeleh catchment were derived from a Digital Elevation Model (DEM). Soil depth was determined at 189 systematically randomized positions of the catchment by soil drilling. Data of soil depth and topographic attributes were analyzed using SPSS 19 software. Results showed that the soil depth predicted by the model had significant negative correlation (P

The aim of this study is ecological investigation of Cerasus mahaleb (L.) Mill relation to some physiographic and edaphic conditions in this sites (10 ha area). in order to achievement to the most important factors on distribution of cerasus mahaleb (L.) Mill (PCA) method was used. Results showed that most important factors affecting on the establishment and distribution of Cerasus mahaleb (L.) Mill were Elevation, Ca, aspect and lime, slope, N, P, pH, clay, stony percent, organic matter, silt, K and C.