نشریه بوم شناسی جنگل های ایران
پیاپی 21 (بهار و تابستان 1402)

Rural ecotourism is a process that has existed for a long time with its own forms in order to provide the psychological, cultural, social and economic needs of humans and is one of the growing indicators. Therefore, today, rural ecotourism has become one of the main levers of economic and social development in many regions of the world. This process in different regions should be based on sustainable development in order to protect the historical and cultural heritage of the region along with the rational use of natural resources and also protect the desired nature.Therefore, before formulating strategies for the development and implementation of economic and social programs, the geographical survey of the region and the recognition of its environmental capabilities and then determining the ecological potential of the land, with the aim of continuous exploitation with the least destruction and preservation of resources Natural is an inevitable necessity. Therefore, rural ecotourism has a special place and remarkable growth among different types of tourism, and we have witnessed the rapid expansion of rural ecotourism activities all over the world in the last 20 years. Also, it is expected that this will be added. But considering the importance of nature protection, planning and management, rural ecotourism based on scientific principles is one of the necessary approaches in the process of achieving sustainable development and preventing waste of time and capital.

The purpose of this study is identification and customization rural ecotourism criteria and indicators in a descriptive-analytical method based on the Delphi questionnaire completion by using the opinion of experts and specialist in this field. Therefore, 44 rural ecotourism experts and specialists answered the Delphi questionnaire in three phases, which it includes a set of criteria and indicators of rural ecotourism extracted from various sources. In this research, the standard deviation index and Kendall's coordination coefficient were used to reach a consensus among Delphi members, that is, to converge their opinions. In this study, in order to investigate the internal stability of the questionnaire questions, Cronbach's alpha coefficient reliability measurement technique was used.

Analysis of the findings of the study has identified 4 criteria and 54 indicators for rural ecotourism. Finally, 4 criteria and 44 indicators were customized and prioritized to evaluate rural ecotourism. The results of prioritizing rural ecotourism indicators using the Delphi method showed that in terms of environmental, social, economic and technical criteria, the indicators of the presence of green spaces, forests, pastures, wetlands and rivers, and etc; architectural style and handicrafts, clothing and foods; the presence of local rural markets and the presence of religious, historical, ancient, pilgrimage, artificial, cultural and social places and attractions have respectively been assigned the highest priority among other indicators of rural tourism.

These criteria include environmental, economic, social and technical criteria. The results of prioritization rural ecotourism criteria showed that technical and environmental criteria with an average of 4.37 and 3.94 had the first and second priority respectively. Therefore, it is suggested to pay more attention to the criteria and indicators with high priority of rural ecotourism in management plans for the implementation of rural ecotourism projects.

For about two decades, the Zagros forests have been facing a declining issue, and the effects of this crisis are visible in various regions.

In the current study, the effect of climate change on the decline of Persian oak in the Zagros forest stands is probed using meteorological data and sample plots over time. To conduct this research, in order to collect field data, a regular random sampling model with fixed sample plots with two sampling periods in 1998 and 2018 was used. Furthermore, the trend of four climatic elements of precipitation, temperature, frost, and relative humidity in Gilan-e-Gharb station from 1988 to 2018 was studied.

The results showed that the frequency and stock of Persian oak species in the second period compared to the first period was decreased. The cross-sectional per hectare of Iranian oak was decreased from 5.2 in the first stage sampling to 4.4 in the second sampling. The results of comparing the quality and health conditions in two samples showed that in the first period, 11.9% of Persian oak trees were decayed and dried, while in the second period it was 71.55%. The oak decline rate in the second-period sampling was higher in health and quality grades 2 and 1 (41.9% and 28.5%, respectively) and was decreased in grades 4 and 5 (8.2% and 3/1%, respectively). However, the deterioration in higher degrees leads to the death of Persian oak trees. The Mann-Kendall analysis results of climatic elements showed that during the study period, the trend of precipitation, frost, and relative humidity was decreasing and the temperature was increasing. In the first decade and to some extent in the second decade, noticeable stability was observed in the studied indices, but in the third decade, there were many fluctuations.

According to the obtained results, it can be said that climate change and the occurrence of severe drought stresses cause oak trees to suffer from physiological weakness. By creating physiological weakness in the trees, the conditions for the invasion of pests and various diseases are provided to them and the oak tree goes to dryness and decay.

Forest canopy gaps play an important role in forest dynamics. Unmanned aerial vehicle (UAV) data provide demonstrated capacity to systematically and accurately detect and map canopy gaps and have been considered as an alternative way to describe the forest stands. This study aims to extract canopy gaps using UAV data and compare the performance of different canopy gap extraction methods in a part of the replanted forest in the Arab Dagh Region, Golestan Province, Iran.

After the acquisition of UAV images and initial preprocessing, the digital terrain model (DTM), digital surface model (DSM), Canopy height model (CHM), and orthophoto mosaic were produced. CHM classification performs to extract forest gaps by different methods of height thresholding on CHM, CHM slope thresholding, and object-based classification. For performance evaluation of used methods and accuracy assessment of the canopy gap maps, the central position and boundary of some gaps were measured by DGPS. Finally, the point and polygon base accuracy of delineated gaps were assessed for each of the methods..

The results of the point accuracy assessment showed that the canopy gap map obtained by object-based classification method with applying the support vector machine (SVM) algorithm with 99% overall accuracy and 0.98 kappa coefficient had the best performance compared to other algorithms and methods. About area accuracy assessment, the best match between delineated gaps and ground truth polygons was achieved by using 3 m height thresholding.

The results showed that with aerial images of the UAV and its outputs, as well as the use of automated methods, the map of the canopy gap can be accurately extracted. Of course, the degree of accuracy depends on several factors such as the type of drone and cameras used, flight parameters and so on. Given the results, it is hoped that this approach will gradually be used as a cheap and accurate method in forest surveying.

The decline of natural forests has been caused urban afforestation to acquire a particular importance with the purpose of green space development level, therefore, the selection of appropriate plant species plays a substantial role in the development and stability of urban green space. The nutrients evaluation is significant in in selection of appropriate species for planting and in a way that species can be selected and supplemented by either consumption of the whole available nutrients in habitat or with their accompanying species.

The present study was conducted to evaluate the high consumption nutrients (Nitrogen, Phosphorus, Calcium, Carbon, Magnesium and Potassium) in the leaves of Mulberry, Ash, Tehran Eldarica Pine and Arizona Cypress in two summer and autumn seasons in four geographical areas (Jamshidieh Park, Sorkheh Hesar Park, Vard Avard Park and Shaghayegh Park) in Tehran. Also, retranslocation of nutrients was measured in four parks and three species (Mulberry, Ash and Tehran Eldarica Pine). At the end of the growing season, the mature green leaves (80 samples) and at the end of the autumn season, the fallen leaves (60 samples) were collected at the base of the tree and packed in zippered bags with the desired specifications on them and transferred to the laboratory. The leaves were washed with sterile distilled water to remove contaminants, then dried in an oven at 70 ° C for 24 hours and then ground. Chemical analyzes were performed using standard instructions. Statistical analyzes such as general comparison of means (one-way analysis of variance) and group means (Duncan test) were performed.

The results of this study showed that the average nutrients in summer leaves are higher than autumn leaves. In Sorkheh Hesar, Shaghayegh and Jamshidieh parks, in summer leaves, the highest amounts of nutrients related to calcium (62.66 mg/g in Shaghayegh Park) and in Alder was recorded. While in Vard Avard Park, the highest amount of this element was observed in mulberry (68.32 mg/g). In autumn leaves, in three parks of Shaghayegh, Jamshidieh and Vard Avard, the highest concentration of nutrients related to calcium (42.66 mg/g in Shaghayegh Park) and was recorded in mulberry. While in Sorkheh Hesar Park, calcium concentration was recorded in Alder (50.66 mg/g). Regarding the percentage of nutrient retranslocation in the studied species in Sorkheh Hesar Park Magnesium (63.04%) in Alder, in Shaghayegh Park Potassium (52.58%) in Mulberry, in Jamshidieh Park Potassium (63.79%) in Tehran Eldarica pine and in Vard Avard Park calcium (41.45%) in mulberry had the highest nutrient retranslocation.

The species studied in this study had different nutrients in their summer and autumn leaves. These species also retranslocation a different amount of each element. It is suggested that this issue be taken into consideration in the management and planning of urban forestry, and the tree species used, which are mainly the main tree species in urban forestry, should be classified based on the status of nutrients.

The side ditch, which is built for the purpose of draining the surface currents and protecting the road construction, is eroded under the influence of the runoff speed during heavy rains and the sediments are transferred to the rivers and water ecosystems. Determining the impact thresholds of rainfall in different protection treatments on the sedimentation process of the side ditch can be a suitable tool for managing and planning the side ditch protection of forest roads throughout the year. The use of environmentally friendly techniques for the protection of roadsides has a direct effect on the quality and durability of road construction and ensuring traffic safety.

In this research, while monitoring the intensity and duration of rainfall of Dr. Bahramnia's forestry project in Golestan province and collecting data throughout the year, in relation to measuring the amount of sediment delivered after each rainfall through trapping at the beginning And the end of 30 plots of 150 meters in the first year before applying the treatments. The trapping involved digging a cylindrical pit with a diameter of 0.4 meters and a depth of 0.6 meters. Inside each trap, a calibrated indicator was installed to repeat the measurements, and during each visit, the sediment height and deposition level were measured to calculate the sediment volume and then multiplied by the apparent specific gravity of the sediment. In the second year, after identifying the streams that had the highest amount of sedimentation, the treatments of rocking with mountain material, rocking with river material, stair-stepping of the stream and pounding of the bed were carried out and the measurement of sediment after each rainfall, the same as the previous year was repeated.

Pearson correlation analysis showed that amount of sediment yield significantly increased by increasing rainfall duration. But, there wasn’t significant correlation between sediment yield and rainfall intensity. The amount of sediment yield decreased with preparing ditch conservation treatments. The sediment production was begun at 12 hours rainfall with intensity of 6.09 mm hr-1. Sediment production from the treatments of rocking with mountain material, rocking with river material, stair-stepping of the stream and pounding of the bed were 16000, 36000, 12150 and 27000 g yr-1.

With comparisons of conservation treatments it was concluded that riprap with mountainous materials had best performance by sediment reduction of 84%. Nevertheless, it is suggested to carry out more and more comprehensive researches under different conditions of climate, slope and bedrock so that generalizable and practical results can be provided to control the sedimentation of the side streams.

Endophytic fungi are fungi that are present in plant tissue at the time of sampling without obvious symptoms. There are several reports that the use of endophytic fungi improves grain yield, increases cold and drought tolerance, resistance to plant pathogens and herbivorous insects. Therefore, these fungi can be used as a biocontrol agent in the protection of crops. Endophytic fungi are a rich source of active metabolites that have the potential to be used in medicine, agriculture, and industry, so this study was conducted to isolate endophytic fungi from hornbeam trees and their morphological and molecular identification from the forests of Sari.

In this study, to identify endophytic fungi from healthy branches of hornbeam trees during autumn 2019 and summer and autumn 2020 of the forests of Sari city were sampled. In the laboratory, each branch sample was kept for 24 months at 24 ° C and continuous darkness after disinfection and culture on PDA medium. Morphological features and sequencing of the ITS region were performed to confirm the morphological identification and sequencing of the relevant dendrogram using version 7.1 of Bioedit software.

In this study, 9 genera and species were identified. Fungal species includ:Alternaria alternata (OM117707), Aspergillus flavus (OM488258), Botryosphaeria dothidea (OM141395), Diaporthe eres (OM131770), Fusarium acuminatum(OM131729),Fusarium sambucinum (OM142129),Mucor fragilis (OM017151), Neofusicuccum parvum (OM017148), Fulvia fulva (OM124921).

In general, the aim of this research was to identify the fungal endophytes of Beech trees based on morphological and molecular data from the forests of Mahdasht, Tabaghdeh, Darabkala and Imamzadeh Zaid Sari located in Mazandaran province.

The occurrence of fires is one of the important factors that determine the different characteristics of many terrestrial ecosystems. For a long time, fires have severely affected forest areas, and sometimes their negative effects remain for several years after the occurrence of the fire, so that the state of vegetation does not return to its previous state. The aim of this study is to model the restoration of vegetation in Zagros forests (Ilam province) following fire.

We used various climatic and environmental data as independent variables (vegetation at the time of fire (NDVI+1), burn severity index, temperature and precipitation anomaly, average temperature, annual precipitation, slope, aspect, and elevation) and NDVI +5 as dependent variable for the modeling (using random forest, decision tree and gradient boosting) the vegetation recovery following fire. Landsat satellite images were used to prepare indices indicating vegetation density status and burn severity, and after preprocessing the images, these indices were prepared by spectral ratio. Climatic variables (precipitation, average temperature, minimum temperature and maximum temperature) were also estimated according to the regression relationships between these variables and the elevation in the study area. Finally, three machine learning algorithms, including decision tree, random forest, and gradient boosting, were used for modeling, and also the accuracy of these models were evaluated.

The results showed that among the various variables investigated, the annual precipitation, average annual temperature, normalized vegetation difference index (NDVI) and burn intensity index at the time of fire were the most important factors affecting the vegetation restoration post fire in these forests. The precipitation and temperature were the most important factors affecting the restoration among the mentioned factors. Also, the results showed that among the different models, the gradient boosting algorithm with R2 = 0.66 models vegetation restoration better than other models. In this model, the climatic factors were the most important in the vegetation recovery.

According the relationships between the NDVI and other studied factors and the results of the modeling; it is possible to explain the effective role of climate factors in the vegetation restoration in the study area.

Measuring rainfall and its components is essential in forest areas to manage the land's water resources. Throughfall is one of the most important components of the water cycle in forest ecosystems, which has many spatial variations due to the heterogeneous structure of canopy and variable rainfall patterns. However, few studies conducted to determine the optimum samples size for estimating this variable. This study aimed to estimate the number of collectors needed to estimate the average cumulative throughfall of Persian oak (Quercus brantii), pine (Pinus eldarica) and silver cedar (Cupressus arizonica) stands within certain error limit percentage in the semi-arid Zagros forests (Chaoghasabz Forest Park, Ilam County). By determining the appropriate number of collectors, it is possible to have a proper measurement of rainfall and its components in forest areas with acceptable accuracy and saving time and cost.

This research was conducted from October 2017 to February 2018, in natural stands of Persian oak, 30-year eldar pine and silver cedar plantations. The amount of rainfall was measured by five rain gauges located in the open space (outside the canopy), adjacent to the studied stands. The measurement of throughfall was carried out by 27 collectors in Persian oak underneath the canopy and 36 collectors in each eldar pine and silver cedar stands. The average stemflow of five trees in each stand was considered as the average stemflow of the stand. The amount of rainfall interception was estimated from the difference between the amount of gross rainfall and the sum of throughfall and stemflow.

During the study period, 20 rainfall events (in total, 258.2 mm) were measured, and on average, 80, 50 and 59% of it has passed through the canopy in the form of throughfall in each oak, pine and cedar stands, respectively. The mean values for rainfall interception were computed as 46.23 mm for Persian oak, 113.17 mm for eldar pine and 92.17 mm for silver cedar stands. The average number of required collectors estimated with 5, 10 and 15% error percentage of the cumulative average of throughfall at a confidence limit of 95% are 102, 25, and 11 for oak, 5, 10, and 15 for pine and 30, 8 and 3 for cedar, respectively.

According to the results of this study, a positive and strong relationship was observed between the amount of rainfall and throughfall for Persian oak (R2=0.9155), eldar pine (R2=0.8831) and silver cedar (R2=0.8967). On this basis, it can be said that with the increase of rainfall size, throughfall increases. Considering the rainfall regime and the importance of water in these areas, in forestry and modeling of ecohydrological processes in forest ecosystems, priority should be given to planting species with higher throughfall and less interception loss.
The estimated number of 27 collectors is enough to measure average cumulative throughfall of Persian oak with an error of 10%. In the eldar pine and silver cedar stands, where 36 collectors used, this number found to be optimum for measuring the cumulative average of throughfall with an error of 5%. Thus, in the Persian oak stand, the number of collectors should be increased in order to estimate the cumulative average of throughfall with a lower percentage of error, and in the other two stands, the number of collectors was found to be suitable.

Because of possessing a myriad of biological features useful in the biocontrol area, Bacillus species have been in the forefront of studies in this vast yet expanding area of research. Given the preservation of biodiversity and sustainability of the Hyrcanian ecosystems are of utmost importance ecologically and environmentally proper management of this ecosystem warrants serious attention and care. Studies on the microbiome and identification of the species living as endophytes and commensals are by itself a vast area of research in this regard. The present study was aimed at the identification and preliminary biological characterization of the Bacillus strains living as endophyte in the roots of the oriental hornbeam (Carpinus orientalis) growing in Mazandaran and Semnan provinces.

Samples of oriental hornbeam roots were randomly collected from the mountain site of southern Mazandaran and northern Semnan in the Spring 2018. Root segments were surface-disinfected, washed in sterile distilled water (SDW) and crushed in drops of SDW in sterile mortar and pestle. Isolation of bacteria were done following spreading drops of the suspension on plates of tryptic soy agar (TSA) and 3-4 days incubation at 28˚C. The isolates were characterized phenotypically and their protein profiles were determined by electrophoresis on polyacrylamide gel. Diversity of the isolates were assayed by comparing DNA fragment pattern on agarose gels after their amplification by REP-, BOX- and IS-50 PCR. A representative isolate from each of the four DNA profile groups was selected and a 1500bp fragment of the 16S rDNA of each amplified by PCR and sequenced. The nucleotide sequences were aligned and compared with those of a collection of Bacillus species deposited in GenBank using the BLASTn program. A phylogenetic tree of the isolates was constructed using the Maximum-Likelihood method. The ability of the isolates to produce IAA, hydrogen cyanide, protease and biofilm was evaluated.

Thirty Bacillus isolates were recovered from the roots of hornbeam on TSA medium. Based on their phenotypic and molecular characteristics the isolates were differentiated into four groups. Comparison of the nucleotide sequences of their 16S rDNA with the sequences retrieved from GenBank indicated affiliation of the isolates with Bacillus thuringensis, B. cereus, B. subtilis, and B. velezensis among which Bacillus thuringiensis was the most prevalent and B. subtilis the most populated group. All isolates produced indole acetic acid at 5 to 85 mgl- with B. thuringiensis producing the highest and B. velezensis the lowest concentration of the hormone. The majority of isolates were capable of producing lipase, gelatinase, lecithinase, protease, and amylase. Isolates of B. cereus and B. thuringiensis were considerably more proteolytic among all. Producing of biofilm was confined to the isolates of B. velezensis.

The possession of and the diversity in the capacity of producing various biologically beneficial biochemical and enzymes and of having other attributes of value in biocontrol, makes the Bacillus spp. understudy as potentially capable bacteria in the promotion of plant growth and in the biological control of pathogens. Isolates of B. thuringiensis and B. cereus appeared to be superior among the four species studies. This is the first report on the identification and partial characterization of the potentially beneficial Bacillus species living as endophyte in the root tissues of oriental hornbeam in Iran.

In order to protect and protect forests, these valuable resources, it is necessary and necessary to better understand the relationships between plants and the habitat conditions of these ecosystems and the biodiversity in them. Therefore, this research was conducted with the aim of investigating the effect of slope and altitude from sea level on biodiversity in Arasbaran forests.

30 sample plots of 1000 square meters (0.1 hectare) by dimensions 10 m×100m were surveyed in the study area. In the sample plots, the slope and height above sea level were recorded, and the slope was divided into three levels: <20%, 20-30% and >30%, and the altitude from sea level was also divided into two levels, <1700 m and >1700 m. In the sample plots, diameter at the breast height, type and abundance of species were recorded. The biodiversity indices computed were Simpson and Shannon-Wiener's, Margalf's and Menchnik's richness indices, and Pylo's and Hill's evenness indices. Biodiversity indices values ​​were computedby Past software.

According to the results, the highest frequency was related to the species of Quercus macranthera and Crataegus meyeri. The results showed that Hill's uniformity index decreases initially with increasing slope and then increases. Although the amount of other biodiversity indicators increases with the increase of the slope, statistically, the slope does not have a significant effect on these statistical indicators. Also, altitude above sea level did not have a significant effect on Species diversity indices.

The present research showed that the slope has a significant effect on Hill's evenness index and has no significant effect on other Species diversity indices of plant species. Also, the height above the sea level had no significant effect on the Species diversity of tree species of plant species. This importance can be due to the proximity to residential areas and destruction by villagers.

The behavior, spread, and intensity of forest fires are heavily influenced by the type and volume of fuels in a natural region, as well as topography and climate. Assessing the volume of fuels in different forest canopies ‎is very important for crisis management and the prevention of possible fires. The purpose of this study is to ‎determine the amount and type of fuels and fire behavior of Iranian Northern Zagros forests in Sardasht ‎County in different forest densities.

Therefore, according to the statistics of recent fires in Sardasht, the ‎study areas (Nalas and Shiomereh) were selected based on the percentage of forest vegetation cover (open, ‎relatively dense, and dense). In this study, one square meter samples were used to measure the ‎properties of fuels such as average vegetation height, 1-, 10-, and 100-hr time-lag fuels, total fuel ‎volume, and litter volume and depth. Study of fire behavior and spread in two ‎areas was performed using FlamMap and FARSITE fire models using slope, aspect, elevation, fuel ‎model, and canopy cover maps.

The results showed that the total fuel volume in the studied forest ‎areas is 3.9 kg/m2. Also, the maximum 1-hr fuel volume was calculated in dense forest (Shiomereh). ‎The highest fuel volumes of 10-, and 100-hr time-lag fuels were observed in forest areas with relatively ‎dense canopy (Shiomereh). The calculation of the fuel moisture content percentage (FMC%) also ‎showed that forest areas with dense canopy have the highest amount of FMC% among forest lands with ‎relatively dense (Shiomereh) and open (Nalas) canopy. Also, comparison of the real fire spot and the ‎simulated fire spread map ‎in the Nalas region with unintentional fire (with open canopy) with a kappa ‎coefficient of ‎‎0.83 was highly consistent and the model was able to have a significant agreement with ‎‎the actual extent of fire spread. The agreement coefficient in the Shiomereh region with a ‎dense and ‎relatively dense canopy cover due to a deliberate and controlled fire showed a 0.05 ‎agreement. ‎

These findings showed that in addition to the characteristics of the forest fuels, the cause of the fire (intentional and controlled or accidental and unintentional) is also effective in simulating the behavior and spread of fire. The ‎results of this study can be used in firefighting, crisis management, and many studies related to the ‎study of fire behavior and management of forest areas.

Obtaining information and identifying the changes and dynamics of forest ecosystems in different developmental stages is necessary for optimal management, restoration and improvement of forests. The aim of  This research  was to investigate the effect of different development stages of the stand on tree regeneration and understory species in the mixed hornbeam stand in spring and summer (due to the beginning of vegetative activities until the optimal vegetative stage of herbaceous plants) in the forestry plan of Gorgan Shasat-Kalate district two was done.

In order to investigate development stages, after forest surveying, three rectangular half-hectare sample plots with dimensions of 50 x 100 meter for each development stage based on the characteristics provided by Leibundgut and Korpel in the field of the structure pattern of development stages and phases in natural forests were used. In order to study and investigate the vegetation cover, five small sample plots (20x20 meters), one of them in the center and four other in the four corners. In each sample plot, the percentage of herbaceous species cover and the tree regeneration frequency were recorded. To investigate and compare diversity in different development stages, use the diversity indices of Simpson and Shannon-Wiener, and to calculate the richness, use the richness indices of Margalf and Manhinik, and for evenness, use the evenness indices of Smith-Wilson and Evenness in PAST and R software (package Adiv software and specieseve function( were used.

The results showed that the number of plant species in the degradation stage is more than the initial and optimal stages. Diversity indices of understory species and tree regeneration species showed that the diversity of Shannon and Simpson in the two seasons of spring and summer in the optimal stage was lower than the initial and degradation stages. Also, Smith-Wilson and Evenness indices had the highest values in both spring and summer in the optimal stage. The highest value of the Menhinic richness index of understory species was determined in the optimal stage in the spring season, while no significant difference was observed between the different stages in the summer season. The highest value of Margalef richness index of tree species regeneration in both seasons was also observed in the degradation stage.

Based on the results of the present research, it can be stated that different development stages have an effect on the diversity of herbaceous species and forest regeneration. Therefore, there are significant implications of sustainable management on the vegetation layer, which should be considered in future of forest management strategies.

Comparative studies of river flows increase our understanding of the environmental effects of rivers on the vegetation along its borders. The riverine areas are particularly sensitive to the hydrological cycle, which is used as a suitable indicator to show environmental changes. Considering that the plant elements of the riparian forests are affected by river fluctuations and climatic variables. The current research focused on to investigate the effect of the Climate factors and river discharge rate on the growth of white poplar (Populus alba), Russian olive (Elaeagnus angustifolia), and tamarisks (Tamarix sp) .

three species from riparian forest of Aras selected for this research, after select trees, by using increment borer samples were extracted from the stem of the studied species. Tree-ring width of samples were measured and recorded after preparation with using of LINTAB measuring table. After cross-dating tree-ring series of individual samples, final, create general chronology for per species by use of standardization methods and tree-ring chronology obtained for Populus alba with 48 years, Elaeagnus angustifolia with 28 years, and Tamarix spp 23 years.

Investigating showed that Populus alba had a negative correlation to the maximum temperature in September and the average temperature in August and September. The Elaeagnus angustifolia had a positive correlation to the mean temperature in May and a negative to the minimum temperature in August. Elaeagnus angustifolia showed a positive relationship with the river flow in March and a negative relationship in September. The maximum temperature in October and the average temperature in October and December before the growing season had a negative effect on the Tamarisk radial growth. The total monthly precipitation in December and February before the growing season had a positive effect, and in September of the growing season and in January before the growing season showed a positive relationship with Tamarisk. The discharge values in December showed a negative relationship with Tamarisk.

The results of this research showed that the air temperature of the summer months and the low amount of rainfall and river flow in the dry months of the year are the factors that control of the growth of trees. Understanding the impact of climatic variables and river fluctuations on riparian forests can play an important role in planning its restoration, rehabilitation and management. Due to the recent droughts and the construction of dams on the Aras river upstream, the amount of flowing water in the river decreases and leads to a decrease in the level of vegetation on its banks. Therefore, it is necessary to consider affecting factors in the selection of native species in afforestation.

Arbuscular mycorrhizal fungi, due to their very beneficial effects in the growth and development of plants through supplying the water needed by plants, especially in drought stress conditions and increasing their tolerance to salt stress and in general, helping the plant to overcome living and non-living tensions, they are the focus of many researchers. This research was conducted during 2020-2022 with the aim of investigating the effect of flood spreading, vegetation type on the abundance and diversity of mycorrhizal fungi in Kowsar Station.

In spring and autumn, in different land covers, including planted Eucalyptus and Acacia forest, planted pasture with Atriplex bushes with 37 years old and natural pasture in two situations with flood spate irrigation and without spate irrigation. Three samples were prepared from roots less than 1 mm of trees and dominant plants (Heliantemum, Dendrostellera, and Artemisia) in the pasture and the rhizosphere soil up to a depth of 20 cm. After separating and staining the roots, their microscopic examination to determine the presence of symbiosis in the root tissue and to determine the extent of root colonization with mycorrhizal fungi and the extent of mycorrhizal symbiosis based on the extent of root contamination with structures of mycorrhiza was done. The soil passed through a 2 mm sieve was used to separate the spores, and the genus and species of mycorrhizal fungi were identified based on the morphology of the spores using identification keys and information available in scientific sources.

The results showed that the spore density of mycorrhizal fungi in both sampling seasons was higher in areas with flood spreading than areas without flood spreading. The highest spore density in the field of flood spreading in the autumn season is related to H. lippii with the number of spores 50.20 per gram of soil and the lowest with the number of spores 18.80 per gram of soil related to this species in the field without flood spreading in spring. So that the difference between the two was statistically significant with Duncan's test at the 5% level. Also, in all land uses, spore density was higher in autumn than in spring. The highest percentage of root colonization or the percentage of symbiosis was related to Acacia with 61.81% in the field without flood spreading in spring season and the lowest value was related to Eucalyptus with 12.26% in the field without flood spreading in autumn season. In this research, 21 species belonging to 9 genera Acaulospora, Claroideoglomus, Diversispora, Entrophospora, Funneliformis, Glomus, Rhizophagus, Scutellospora and Septoglomus were identified in with and without flood spreading areas. Septoglomus constrictum was the most abundant with 100.0% frequency. Glomus heterosporum and Rhizophagus aggregatum were in the second category with a frequency of 50.0% and Funneliformis mosseae, Glomus ambisporum, Glomus intraradices and Rhizophagus fasciculatus were in the third category with a frequency of 33.3%.

Considering the fact that the identification of mycorrhizal fungi in the rhizosphere of tree plants and pasture bushes in dry areas and their use can be a fundamental step to reduce the negative impact of various stresses, including drought stress, it is suggested the active and effective species of these fungi may be identified and propagated and used as inoculum (biofertilizer) to restore rangelands in these areas.

The forests of Zagros, as the most extensive and at the same time as the most damaged forests of the country, have been affected by the extensive decline of oak trees in recent years, and in this sense, they are in a critical conditions. Decline of oak trees is described as a wide and complex phenomenon that causes a decrease in growth and physiological weakness followed by the attack of pathogenic agents. As sustainability of these forests is now facing a serious problem, proper management strategies are required to deal with the decline phenomenon, before these valuable ecosystems are completely destroyed. The implementation of such strategies necessitates collecting basic information, including map of the decline distribution and the extent of the lost biomass of trees as a result of decay. The purpose of this study is to estimate the amount of biomass on the above-ground in dead oak trees as a result of the decline of Zagros forests, which was carried out in the forests of Dadabad region of Lorestan province.

The present study was conducted in Dadabad forests located in the southwest of Khorramabad, Lorestan, Iran. To achieve this purpose, 40 dried trees were randomly selected and biometric parameters including diameter at knee height, diameter at breast height, as well as height and crown diameter were measured. Different parts of the tree were fragmented, dried, and weighed. Using regression analysis, the biomass of different parts was modeled against the independent variables of diameter at knee height, diameter at breast height, crown height, and diameter. Finally, at the area of 32 hectares of the forest stand, a 100% inventory was conducted, and different characteristics of all Iranian oak trees were measured.

The results of the research declared that strong relationships can be established to estimate the biomass of Iranian oak trees. The result of fitting linear and non-linear models to estimate the biomass of this tree species showed that if the average diameter of the tree crown was used as an independent variable, the more suitable model was the power model with an explanation coefficient of 0.857. Also, the validity results of the model or the value of RMSE% for the obtained equation was 9.082%. The total biomass in the study area was 389.994 tons, of which 39.54%, i.e. 154.226 tons, of the area's biomass was lost under decline phenomenon.

The results indicated that in the comparison between linear and non-linear regression models, the best model for estimating the biomass of this species was the power model based on the average diameter of the crown with R2=0.857. In general, using the average diameter of the crown as an estimator variable for the Iranian oak species can suggest a better and more appropriate assessment of the above-ground biomass of these trees.