جستجوی مقالات مرتبط با کلیدواژه "بوم شناسی" در نشریات گروه "جنگلداری"

The altitude gradient is one of the important ecological factors in the distribution of different types of plant species in forest ecosystems, and the origin of altitude from sea level is related to the difference in altitude from open waters. The change in height from sea level, along with the change in vegetation, can affect the abundance of wood fungi. This research was conducted with the aim of studying the ecological effect of the altitude gradient on the abundance of wood fungi on beech species at different altitudes.

In total, 15 pure beech logs were randomly selected in three altitude gradients: (first) 550 to 650, (second) 650 to 750, and (third) 750 to 850 meters above sea level, in the educational and research forest of Darabkala Sari. To collect samples of wood macroscopic fungi, after observing the fungal samples, each sample was taken in a healthy, complete, and suitable form for identification based on morphological characteristics. Height characteristics from sea level and dry land were recorded with a positioning device, and the samples were transferred to the mycology laboratory for identification. To measure the microscopic organs, 20 samples of each of these organs were measured using a microscope with a graduated lens. Finally, to identify different fungal arrays, identification was based on both macroscopic and microscopic features, using various sources. To categorize the abundance of fungi in different altitude gradients, statistical calculations and cluster analysis were carried out in PAST software, using the Ward and Lesser Eghlidis distance, and analysis of principal components for different altitudes, species, abundance, relative frequency, and standard index were checked in PAST software by comparing two groups of fungi. Additionally, to check for height differences, multiple analyses and double plotting were done in Minitab software to reveal the groupings in terms of cloud points and distribution of wood fungi.

The obtained results showed that in the first height class, 13%, in the second 30%, and in the third 57% of all fungi were included. In the first height class, Hypholoma fasciculare was the most abundant, while Trametes versicolor dominated the second class, and Schizophyllum commune was the most abundant in the third class. Furthermore, the Polyporaceae, Xylariaceae, Ganodermataceae, Pleurotaceae, and Schizophyllaceae families had the highest frequency, while the Pezizaceae and Hericiaceae families had the lowest frequency. The results indicated that 10 species were distributed in the altitude class of 550 to 650 meters above sea level, 15 species were distributed in the altitude class of 650 to 750 meters above sea level, and 22 species were distributed in the altitude class of 750 to 850 meters above sea level. In addition, the most fungi families in the first altitudinal class were from the Meruliaceae family, whereas the second and third classes were primarily Polyporaceae. The analysis with Minitab showed that there is a significant difference in the distribution of wood fungi between the third and second floors, as well as between the first floor and the others. The findings regarding the ecological effect of the altitude gradient indicated that decomposition components reveal differences in fungi at different altitudes above sea level. These results showed that Fomes fomentarius, Ganoderma lucidum, Stereum hirsutum, Daldinia concentrica, Pleurotus ostreatus, Trametes versicolor, Trichaptum biforme, and Schizophyllum commune were among similar groups that were distributed across all three altitude classes, primarily within the Polyporaceae family and the Polyporales order.

The macroscopic wood fungi of the forest exhibit different responses across various gradients. The results of this study showed that the altitude gradient affects the abundance of wood fungi; the abundance of fungal species increases with elevation above sea level.

Competition between trees is a key factor affecting the development, structure, and dynamics of forests. Therefore, many ecologists have sought to quantify competition and related factors in the forest. The forests of Lorestan province with area 1,112,475 ha are part of the important ecosystems of the Middle Zagros, the main type of which is the Iranian oak. One of the important wood species of these forests is Hawthorn, which is often present as an accompanying species and in some areas as a pure forest. This research was conducted with the aim of comparing the crown competition and the spatial distribution pattern of Hawthorn in two forest type formation and companion species.

In this study, two forest habitats Khoshkeroud (with a dominant type of hawthorn) and Perk (with a dominant type of oak) were studied in Khorramabad. After the Search in the forest and determining the areas where the density of Hawthorn species existed and the necessary conditions for calculating crown competition, areas with an area of about 45 ha were determined. In each of these forests with a relatively uniform distribution, the number of 45 Hawthorn stems that had crown overlap with at least one neighbor were identified as central trees. To identify competing trees, the crown overlap method was used, and to quantify the level of competition, the ratio of the crown size of the central tree to the neighbors was used, and to calculate the spatial patterns, the uniform angle index was used. Then information including the distance and azimuth of the neighbors, the height of the central trees, and the size of the diameters of the crowns of the reference trees and competitors were measured. Due to the non-normal distribution of the data based on the Kolmogorov-Smirnov test, the non-parametric Mann-Whitney test was used to compare the means.

Due to the different conditions of the two habitats of Khoshkeroud and Perk, there is an obvious difference in the types and diversity of species in these habitats. In addition, the average distance to effective neighbors in the competition shows a big difference, if other characteristics do not have a big difference. The number of influential neighbors in the BDC index for the Khoshkeroud habitat reaches four neighbors, while in the Perk habitat; there are at most three neighbors with overlapping crowns for the central trees. Meanwhile, more than 80% of the neighbors in the Perk habitat are species other than Hawthorn, while in the Khoshkeroud habitat, other species have allocated a small percentage. In addition to the different admixture, the results of the uniform angle index also indicate the different spatial distribution pattern of Hawthorn species in the two investigated habitats. Despite the difference in admixture and spatial distribution, there is no significant difference between the results of the competition index on the reference trees.

Considering that the Hawthorn genus has been suggested for afforestation of degraded areas in Zagros due to its features such as edible fruit and its ability to be used as a precursor and nurse species, the results of this research can be useful in the field of afforestation and forest cultivation.

Forests are dynamic systems that are constantly undergoing permanent changes. Understanding elements in the forestland ecosystem and factors affecting it will help preserve this ecosystem, as preservation of species diversity will help protect the ecological values of the ecosystem. By studying various environmental factors such as vegetation and topography, soil and climate, we can understand the stability of plant communities and the correlation between these factors and vegetation. This is very important and practical for forest community development and regeneration. The importance of biodiversity and its management especially based on the protection and sustainable use of ecosystem resources is one of the main objectives of natural resource management.

The present study examined unique species and rich specie reserves in the forestland region of Neimour in Iranian Noshahr, aiming to evaluate the vegetation of the edges surrounding the Khezr Nabi swamp. Simultaneously with survey, based on the homogeneity or heterogeneity of the vegetation units in relation to the distance from the marsh, ultimately, the zonation of marsh plants was carried out in three zones and sampling was done. Using the Braun-Blanquet method, samples were gathered by taking 1×2 meter frames in eight geographical directions. Plant species diversity in the growing season was examined using the Simpson and Shannon-Weiner indicators, and the richness and uniformity of the species were measured using menhinick and margalef richness indicators.

The results of this study, taken from biodiversity indicators, suggested that the most species diversity and richness pertained to the east, north and northeast, with the swamp directions noting no statistical differences; but a statistical difference(p<0.05)was observedin menhinick and margalef richness indicators. The soil texture, including sandy clay loam (62.5%), sandy loam (25%) and loam (12.5%).The clay(p<0.01), organic matter(p<0.01)  and soil acidity (p<0.05) characteristics have significant differences. The study also found that in terms of the number of the species, most species pertained to the beech trees, while in herbal and fauna species, the Gramineae family and soil ant family were seen most in the northern direction.

As the findings suggested, the cover tree, fauna, and the edaphic cover were affected by the Khezr Nabi swamp, which formed a sub-habitat with a special micro-climate.

With sufficient knowledge regarding the presence of fungi and the significance of biodiversity, the forest's management objectives can achieve their sustainability goals. Therefore, in order to properly manage the forest, it is necessary to establish indicators that provide adequate information on biodiversity and monitor changes resulting from management activities. This study aims to identify various macroscopic fungi and investigate their biodiversity in their habitat, i.e., deadwood.

Fifteen specimens of deadwood fungi were randomly selected in Darabkola forest. All macroscopic fungi were numbered and collected, then transferred to the mycology laboratory for identification. The biodiversity of the fungi was calculated using Shannon-Wiener diversity index, Simpson diversity index, richness index, and uniformity index with PAST software

The obtained results revealed that there were 37 species of macroscopic fungi belonging to 27 genera and 16 families. Trametes versicolor, Daldinia concentrica, Trichaptum biforme, and Fomes fomentarius were the most abundant, while Hericium coralloides, Ganoderma resinaceum, Ganoderma adspersum, and Trametes trogii were the least abundant species. Additionally, the families Polyporaceae, Xylariaceae, Ganodermataceae, Pleurotaceae, and Schizophyllaceae were the most abundant, whereas Pezizaceae and Hericiaceae were the least abundant. Most fungi were present in the final stages of decomposition. The results indicated that the mean diversity index for Shannon-Wiener species diversity was 3.24, Simpson species diversity index was 0.95, Margalef's richness index was 6.11, Menhinick's index was 1.95, and uniformity was 0.69. The analysis of the Shannon-Wiener diversity index showed that Trichaptum biforme and Trametes versicolor had a higher diversity value with a score of 1.46.

The results of this study indicate that for the management of fallen deadwood habitats with the aim of increasing the biodiversity of fungi, it is recommended to preserve these fallen deadwood areas within the forest. This preservation would contribute to the revitalization and completion of the ecosystem cycle.

Maintaining the structure and biodiversity of ecosystems is considered to be one of the most important goals of modern forestry. For this purpose, the tools are needed for forest management, to have the lowest cost and time to check the current status, as well as the changes caused by development of forest management activities. Indicators of nearest neighbor have advantages that their application gives priority to direct measurements of biological diversity. Because in addition to the study of species diversity, it investigates the locations of trees. Also nearest neighbor indices provide valuable information about ecological interactions of trees in forests. Therefore, this study was aimed to introduce and apply important indices based on nearest neighbor analysis to study ecological relationships of trees in beech-hornbeam stands in Nave Asalem- Gilan forests.
In order to do this research, seven 1-ha plots with homogeneous environmental conditions were inventoried in a Fageto-Carpinetum association in Nave Asalem- Gilan. In each plot, distance and azimuth of all trees on the plot with more than 7.5 cm diameter at breast height from the center of sampling area and species, and diameter at breast height were recorded. The spatial pattern and species diversity were then investigated using the uniform angle, mean directional, species mingling and segregation indices. The amounts of each of the mentioned indices were calculated for each sample individually. The average of the values obtained for each sample were calculated for the Fageto-Carpinetum.
The results showed in seven 1-ha plots of Fageto-Carpinetum, Fagus orientalis, Carpinus betulus, Acer cappadocicum, Acer velutinum and Alnus subcordata had the maximum density per hectare. The values of uniform angle and mean directional indices were 0.53 and 2.02, respectively, showing a spatial distribution between random and clustered. In terms of species diversity, the Fageto-Carpinetum association with an average of 0.47 and 0.25 for species mingling and segregation indices, respectively, presenting a medium level of species mixing. The amount of species mingling indices indicated low level of mixing of beech species and high level of mixing of other species. The segregation index showed a pair of trees or nearest neighbor reference trees belonged to different species.
In general, the results of this study indicated the efficiency of nearest neighbor indices to study the structure of Fageto-Carpinetum associations and the results can be used for planning to revitalize the structure and status of biodiversity in degraded Fageto-Carpinetum associations.