mehdi pourhashemi

Severe droughts and catastrophic floods are major challenges resulting from climate change in the Zagros forest ecosystem. Climatic anomalies such as heat waves and prolonged droughts can create favorable conditions for pest and disease outbreaks, leading to the decline of oak forests. The Zagros oak forests are situated in semi-humid and semi-arid climatic zones and, due to their location in the global dry belt, frequently experience recurrent droughts. The biodiversity and ecological role of these forests, acting as a protective belt and natural barrier, highlight their significance. Spanning 11 provinces and covering an area of 6 million hectares—accounting for 40% of Iran’s forests—the management and planning of this ecosystem is highly complex due to its vast extent and the influence of various environmental factors. Identifying areas that experience more frequent, prolonged, and severe droughts can help forest managers mitigate damage and enhance adaptation to current and future climate changes.

To assess drought occurrence in the Zagros ecosystem, the Standardized Precipitation Index (SPI) was utilized to analyze the temporal distribution of drought frequency, duration, and severity over a 28-year period across three selected stations in northern, central, and southern Zagros. Based on regional conditions and classifications from Iran’s National Drought Center, the SPI was categorized into nine classes. The index was calculated for synoptic stations with a 28-year statistical record at 3-, 6-, and 12-month timescales using ClimPACT software. Given the vast study area, the Zagros region was divided into three sections (northern, central, and southern), and drought severity and duration were visualized through graphical representations. After evaluating drought intensity, duration, and frequency across all stations with more than 28 years of data, the percentage of drought-affected areas was calculated for the entire Zagros ecosystem over a common statistical period (1992–2019). The spatial distribution of drought severity during peak drought years was mapped using the ordinary kriging method in ArcGIS software. By identifying years when widespread drought affected the entire Zagros, regions experiencing severe and extreme droughts were classified as critical zones for conservation and research efforts.

The findings indicate no significant difference in drought severity across northern, central, and southern Zagros; however, the timing of the most severe drought events varies. Across all timescales, the longest drought period occurred between 1999 and 2001, coinciding with the onset of forest decline in the Zagros. Notably, from 2007 to 2017, more than 40% of the Zagros region experienced prolonged drought. While droughts can extend over hundreds of kilometers, their intensity and duration are not necessarily uniform across the entire region. Analysis of drought extent from 1992 to 2019 revealed that during certain years, such as 2006 and 2018, no drought events occurred, and the entire Zagros experienced wet conditions. In some years, mild droughts affected less than 10% of the region. However, between 2007 and 2017, more than 40% of the Zagros suffered from prolonged droughts, with certain years, such as 2008, experiencing drought conditions across the entire ecosystem. During this period, in 2010, over 80% of the Zagros region faced drought, and in 2017, this figure exceeded 70%. Notably, before this prolonged dry period, a relatively wet phase lasted for nearly five years.

While multiple factors have contributed to the decline of the Zagros forests, drought has been a primary driver, facilitating the impact of other stressors. The extended duration of droughts has hindered the recovery of trees, while the extreme severity of events—such as the 2008 drought, which affected the entire Zagros—has exacerbated forest decline. Although alternating wet and dry periods are characteristic of the Zagros climate, prolonged drought episodes have heightened ecosystem vulnerability. Severe droughts, when followed by a wet year, tend to have less impact compared to persistent mild droughts. Identifying areas subject to severe and continuous droughts can aid forest managers and policymakers in implementing effective conservation and restoration strategies.

Oak decline is a critical issue in Zagros forest ecosystems. Disruptions in nutrient and water uptake, exacerbated by environmental stress, weaken trees, leading to deterioration. Soil physico-chemical characteristics significantly influence forest habitat performance. Given the spread of dieback trees in Kurdistan province, this study aimed to investigate changes in deep soil parameters associated with control stands (healthy trees) and dieback trees in the coppice stands of Marivan county, northwest Kurdistan province.

The study was conducted in dieback (Garan) and control (Dolah Naw) forest stands in Marivan county. Within each stand, ten trees (five healthy and five dieback) were selected across north and south aspects (totaling 30 trees: 10 in the control, 20 in the dieback habitat) and numbered in 2018. Soil samples were collected on the northern side of the crown, one meter from the tree trunk at a depth of 20-40 cm (first week of August). Laboratory analyses determined moisture percentage, pH, electrical conductivity, available phosphorus, potassium, nitrogen percentage, organic carbon percentage, lime percentage, calcium, and magnesium. Principal Component Analysis (PCA) using PC-ORD 5 software was employed to assess the effect of deterioration on soil physico-chemical characteristics.

Statistically significant differences were observed among the ten physical and chemical parameters across the six treatments. The highest average values for electrical conductivity (599 decisiemens/cm), moisture (13.1%), lime (13.8%), available phosphorus (13 mg/kg), and potassium (1317 mg/kg) were found in soil near trees on the northern slope of control stands. Conversely, the highest levels of organic carbon (3.75%), nitrogen (0.32%), and calcium (44.2 milliequivalents/100g) were observed in soils beneath healthy trees on the southern slope of control stands. Generally, control stands (both northern and southern aspects) exhibited higher values for most soil physico-chemical parameters, except pH and magnesium. Dieback trees showed nutrient and macronutrient deficiencies, with lower element concentrations in the soil under their crowns. PCA revealed that electrical conductivity and moisture had the highest positive loading (0.42) on the first component, while organic carbon and nitrogen loaded at 0.41. Calcium, lime, and pH loaded on the second component with positive values of 0.55, 0.53, and 0.49, respectively. PCA also indicated better soil moisture in healthy trees on the northern slope.

Soil physico-chemical parameters and macroelement concentrations were generally higher near trees in control stands compared to dieback-affected stands. For optimal management of dieback trees in the research area, soil enrichment and strengthening, enhanced protection measures (livestock grazing and traditional exploitation control), increased forest restoration and development in dry areas (particularly southern slopes), and sanitary cuts (branches and stems with red cracking and deterioration) are recommended.

 Fluff pulp is a hygienic paper with high grammage, which is used in the production of hygienic products such as baby diapers. In this research, the possibility of manufacturing fluff pulp using spinning mill wastes was investigated.

For this purpose, those part of spinning mill wastes that are based on cotton, were cleaned physically and after washing one time with cold water, they were subjected to a soda (15%) pulping process. Total yield, kappa number and ash content of the resulted pulp were measured based on the related standards. The bleaching step of the spinning mill wastes pulp was performed using a sodium hypochlorite-alkaline extraction- sodium hypochlorite (HEH) sequence. Tests like brightness, ash content, kappa number and the bleaching yield were done on the bleached pulps in order to evaluate the efficiency of bleaching. The bleached pulp then was refined by a laboratory refiner with varying refining rounds and for the fabrication of fluff pulps, hand-sheets with the basic weight of 750 g/m2 were manufactured. SR freeness, density, water retention value (WRV), the burst and tensile indices of refined pulps, were also evaluated.

The results showed that the pulping soda process, the abovementioned bleaching sequence and refining of resulted pulp led to the production of fluff pulp with extra ordinary features. In this way the effect of refining intensity was quite obvious and the results showed that with the increase of refining rounds, SR freeness, density of fluff pulp and WRV were increased continuously. With the increase of refining intensity up to a certain value, the burst and tensile indices of the manufactured fluff pulp also increased, but further increase in refining intensity led to a decrease in these indices.

The results of this research showed that reusing the spinning mill waste for producing a hygienic product such as fluff pulp can be very beneficial both from an environmental point of view by helping to prevent deforestation and from a technical point of view.

The dynamics of spatial structure play a major role in understanding the mechanisms of forest structure and the formation of biodiversity, and largely determine the sustainability of the forest and its productivity. As part of a long-term monitoring project, the present study was conducted to assess the structure of juniper (Juniperus excelsa M.B.) stands in the Parvar protected area of Semnan province in the Irano-Touranian vegetation zone. Two permanent sample plots, each one hectare, were randomly selected, and the quantitative characteristics of woody species were measured and recorded using the full calipering inventory method. The structural characteristics of the stands were calculated based on the nearest neighbor indices. In sample plot one, juniper was the most abundant species, accounting for 49.7% (94 stems), while Rosa canina was the least abundant, with 4.8% (9 stems). Berberis integerrima and Cerasus microcarpa accounted for 39.7% and 5.8% of abundance, respectively. Sample plot two, with 75 stems per hectare, consisted of only two species: juniper (54 stems, 72%) and barberry (21 stems, 28%). The Clarke and Evans index and uniform angle indices indicated a clustered spatial distribution pattern of trees. The species mingling index for the entire stand in sample plots one and two was 0.46 and 0.38, respectively, indicating moderate mixing. The combined structural diversity index value was 0.47 and 0.48 in sample plots one and two, respectively, suggesting high diversity in the investigated stands. This study demonstrated the effectiveness of these indices in estimating the horizontal structure of forest stands, providing valuable information essential for management and decision-making processes.

Zagros forests, as a second forest ecosystem in Iran. These forests have diverse ecosystem services and have a valuable position in terms of ecology, economy and society, and carbon storage. Tree species are one of the most important factors influencing soil characteristics through the production of litter and play an essential role in the carbon storage. Also, fine woody litter and coarse woody litter are very important to increace the carbon storage in forest soil. The purpose of this study is to investigate the trend of carbon storage of fine woody litter and coarse woody litter in the Marivan forests of Kurdistan province between 2019 to 2021 years.

To do this research, a two-sample plot (one-hectare) was selected in Garan (protected and protected stands) and Dolah Naw (typical forests of the Marivan county). The research was do from 2019 to the end of September 2021, and to ensure the location of the center of the microplot, the location of the microplot was recorded and marked. At the end of September of each three years of the study, by implementing 10 micro-samples of 0.5 square meters. In order to measure the dry weight and carbon stock, the samples of small scraps and wood chips were placed in an oven at 104 degrees Celsius for 24 hours according to the ASABE S358.2 (2010) standard, and then the dry weight of the samples was immediately calculated. To measure the percentage of organic carbon in the samples of scrap and wood chips, the combustion method was used in an electric furnace, and the samples were placed for 4 hours at a temperature of 550-600 degrees Celsius, and after measuring the percentage of carbon, the percentage of carbon was calculated, and then it was calculated by multiplying the percentage of carbon by weight. After the samples were dry, the weight of carbon was calculated for each microplot (separated by carrion and wood chips). in each sample, fine woody litter and coarse woody litter were sampled and samples of scraps and pieces of wood are packed in the storage space and their dry weight, percentage moisture, carbon percentage and carbon storage amount are measured in the laboratory. Two-way analysis of variance test was used to compare carbon percentage, dry weight and carbon storage of fine woody litter and coarse woody litter, and the effect of two stands (site) and sampling period (two years of research include 2019 and 2021) on research parameters was investigated. Also, Duncan's intergroup comparison test was used to check and compare the research parameters in three sampling periods. Data analysis and statistical comparisons were done using SPSS 20 software.

The finding showed that the dry weight of fine woody litter was 4.46, 2.89, and 4.94 tons per hectare in the years 2019, 2020 and 2021, respectively, and the average fine woody litter in Garan site was higher than that of Dolah Naw. Garan site fine woody litter carbon was estimated as 1.878, 1.21, and 2.009 tons per hectare in the three years of study, and these values were higher than Doleh Naw site. The results of two-way analysis of variance showed that the difference in dry weight and carbon storage in two stands (site) was statistically significant. Also, the average dry weight of coarse woody litter in the sample plot of Garan in the years 2019, 2020 and 2021 was 0.456, 0.327 and 0.599 tons per hectare, respectively. 0.214, 0.178 and 0.322 tons per hectare were confirmed, and in total, the carbon storage of coarse woody litter in Garan habitat was more than that of Doleh Naw, and this difference was statistically significant. On the other hand, the average carbon percentage of fine woody litter in Garan sample plot in 2019, 2020 and 2021 was 42.07, 42.22 and 41.03%, respectively, and the carbon percentage of fine woody litter in Garan sample plot was more than Doleh Naw. Based on the two-way analysis of variance test for coarse woody litter, a significant difference was observed for the parameters of dry weight, carbon storage and carbon percentage of the samples in the years of statistical collection, but no significant effect was observed in the context of the site and the interaction effect of year × stands (site). In general, in the Garan site, the carbon storage of fine woody litter and coarse woody litter was estimated as 4.09 and 0.46 tons per hectare, respectively, which was more than Dolah Naw (with values of 3.55 and 0.39 tons per hectare). The highest carbon storage in fine woody litter and coarse woody litter occurred in the years 2021, 2019 and 2020, respectively. The general results showed that the amount of carcass dry weight and carbon storage in Garan site was 0.14 more than Dolah Naw site.

The general findings of the research showed that the average dry weight and carbon storage for fine woody litter and coarse woody litter in Garan stands (site) was higher than Doleh Naw stands and according to the positive effect of protection on the amount of carbon storage a fine woody litter and coarse woody litter; in order to optimally manage the study forests and other similar forests, it is suggested to manage and use protection in degraded areas. Forest restoration and development increased the amount of fine woody litter and coarse woody litter.

This study was conducted in the Zagros forests to investigate and monitor the status of elements in the soil and their absorption in areas with and without oak decline. Two plots, each with 100 trees, were randomly established in the south direction in the areas of "Sama Castle" and "White Mud," representing the decline and control (without decline) sites. In the oak decline plot, five healthy and five declining trees were selected, while only five healthy trees were chosen in the control plot. Selection of healthy and declining trees in the first year was done selectively and with proper distribution throughout the sample. In the following years, soil and leaf samples were collected from the selected trees. Soil samples were collected under the tree crowns at two depths (0-30 cm and 30-60 cm). Additionally, 20 leaves per tree were sampled in late July and early August. The results showed that the amount of phosphorus in the leaves of trees in the both decline and control sites was significantly different at a 99% confidence level. As the intensity of drought increased, the amount of phosphorus in the leaves also increased. Soil moisture was estimated at 5.74% in the decline site and 7.14% in the control site, with this difference being statistically significant. The amount of calcium in the soil of the control area was approximately 1.5 times greater than in the area experiencing decline. The results of this research, focusing on soil characteristics related to oak decline, can provide important data for the oak decline information system in the Zagros forests of Iran.

This research measured and analyzed forest ground vegetation in permanent plots of typical and exclosure areas in the Zagros provinces, providing the possibility for long-term monitoring of quantitative and qualitative changes in vegetation. In total, 30 one-hectare square sample plots and 600 one-meter square microplots were studied along the Zagros, with floristic and environmental data related to tree and forest floor measured and recorded. According to the results, 370 species were identified in the ground vegetation and 20 species of phanerophytes. The most abundant families in exclosure and typical sites were Asteraceae and Poaceae, respectively. Sixty-six percent of the ground vegetation population belonged to the Poaceae family, with the most populated genus being Bromus, comprising 25% of all plant individuals. The largest genus was Astragalus (with 18 species), and its population was about 2.5 times higher in exclosure sites than in typical sites. The average percentage of ground cover (51.2%) and litter cover (34.3%) in exclosure plots was significantly higher than in typical plots (37.6% for ground cover and 25.2% for litter cover). The number of phanerophyte species in the exclosure area was significantly greater than in the typical area, while the difference for other life forms was insignificant. The comparison of diversity indices for ground species in the exclosure and typical plots showed no significant difference between these two groups. In general, the relative protection implemented in some parts of the Zagros, although it did not affect ground species diversity indices, did affect ground vegetation cover, litter cover, species composition, and phanerophyte species.

This research was conducted on two square plots (each 1 ha) located in Vezge Mansurabad (a protected area in Boyer-Ahmad County) and TuteNadeh (in Dena County) in Kohgiluyeh and Boyer-Ahmad province. Five soil samples, taken regularly over three years from a depth of 0-30 cm from each plot, were analyzed for carbon, nitrogen, phosphorus, water content, microbial respiration, soil bulk density, and gravel percentage. The mean carbon storage of soil was estimated at 84.80 t/ha and 67.60 t/ha in the TuteNadeh and Vezge Mansurabad plots, respectively. Three years of monitoring revealed a significant difference between the two plots in terms of soil parameters. In TuteNadeh, the three-year changes in organic carbon and total nitrogen content followed a parallel trend, with a reduction in the former directly leading to a similar drop in the latter's content. At this site, the content of absorbable phosphorus was found to be irregularly altered. Variations in organic carbon content were directly correlated with variations in soil microbial respiration. In Vezge Mansurabad, variations in organic carbon, nitrogen, phosphorus, water content, and microbial respiration were similar to those in TuteNadeh, but variations in soil phosphorus were sinusoidal and followed an irregular pattern. The mean quantities of absorbable phosphorus, water content, and microbial respiration in the TuteNadeh plot were 15.44 mg/kg, 12.59%, and 434 mg/kg, respectively, which are significantly different from the corresponding values of 10.05 mg/kg, 13.94%, and 547 mg/kg in Vezge Mansurabad. In conclusion, the results show that soils with higher organic carbon content are relatively richer in other influencing variables.

The Zagros forests, being the largest and most important forest ecosystems in the country, provide valuable ecosystem services. The percentage of forest canopy cover, a crucial component of forest statistics, has a strong relationship with ecohydrological processes and plays a vital role in forest inventory programs. In this study, changes in canopy cover percentage were examined in sample plots located in the provinces of Kurdistan (Dulehnaw, Gharan, Belveh, and Saraki) and Chaharmahal and Bakhtiari (Gelsefid, Rahimabad, Gardaneh Cheri, and Mavarz), representing the northern and southern Zagros forests, respectively. Each plot underwent a comprehensive measurement process, including the assessment of species composition, growth form, and average crown diameter. Static images of tree canopies were captured in 2021 and 2022 to analyze changes in canopy cover. The analysis revealed statistically significant differences in canopy cover between provinces. Significant differences in canopy cover changes were observed in the Dulehnaw, Gharan, and Rahimabad forest stands over the two years, but no significant statistical differences were found in the Saraki, Belveh, Gardaneh Cheri, Mavarz, and Gelsefid stands. Furthermore, in both provinces, the highest increase in canopy cover percentage was recorded in the southern direction, with values of 7.46% and 3.97%, respectively. Detailed and comprehensive analyses of the canopy cover index, particularly in the Zagros region, are crucial for effective management planning in forest ecosystems. The two-year variations in this index provide valuable insights into the influence of vegetation type, structure, and ecological conditions on canopy dynamics, serving as a gateway for energy to plants.

The Zagros forests vegetation area, with an area of more than 5 million hectares and providing more than 40% of the country's water, is ecologically very important. The forest covers 256,000 hectares of Kurdistan province (8.8% of the province) and makes a significant contribution to carbon sequestration. Atmospheric carbon dioxide has increased significantly in recent decades. In reducing atmospheric carbon dioxide, vegetation and the soil beneath it play a very important role. The aerial parts of trees (the ground layer) contribute greatly to biomass production and carbon sequestration. The purpose of this research was to investigate the carbon sequestration of the tree layer in two sample plots: Garan (Gargh and protected stands) and Dolah Naw (typical forests of the province).

 In order to carry out this research, two samples from Garan and Dolah Naw in Marivan County were selected. In each region, a square sample plot of one hectare was established, and with 100% statistical inventory, quantitative characteristics, including tree species, breast diameter, tree height, crown height, and crown area, were recorded. In both sample plots, the trunks and top branches of the trees were sampled, and for this purpose, three trees were selected for each species in each plot. Samples were taken from the trunk, main branches, and secondary branches of the trees. In the laboratory, the wet weight, dry weight, and carbon percentage of wood samples were calculated by burning the dried samples in an electric furnace. Then, the above-ground biomass of trees was calculated using allometric equations, and finally, the carbon stock of all trees was estimated. The quantitative parameters and the average of the above-ground biomass and carbon stock were compared. An independent t-test was used to compare quantitative parameters and carbon storage in the two sample plots of Garan and Dolah Naw.

 The findings of the research showed that the amount of biomass on the ground in Dolah Naw and Garan sample plots was 45.3 and 41.4 tons per hectare, respectively. In the Dolah Naw sample plot, two species, Quercus brantii and Q. infectoria, with a total of 24.68 tons per hectare, accounted for 54.5% of the biomass of the tree layer. The carbon stock of the tree layer in Dolah Naw and Garan samples was calculated as 22.4 and 20.3 tons per hectare, respectively, and the results of the independent t-test showed a significant difference between the quantitative characteristics of diameter at breast height, total height, tree crown area, biomass, and carbon storage in the two sample plots. The contribution of the Q. infectoria species to carbon sequestration in Dolah Naw and Garan samples was 6.48 and 9.13 tons per hectare, respectively. On the other hand, the averages of quantitative characteristics, including tree height (3.7 meters), diameter at breast height (15.79 cm), and crown area (6.77 square meters), in the Dolah Naw sample plot were greater than those in the Garan sample plot.

 The general results showed that the carbon storage of Dolah Naw stands (wood biomass with slightly higher forest characteristics) was greater than that of Garan forest. To optimally manage these forests and increase carbon dioxide storage, it is essential to manage and control the factors of forest destruction (such as the development of agriculture under the forest canopy, intensive grazing, excess livestock capacity, fire management and control, coal mining, and other factors) and take action in degraded areas to promote reforestation and afforestation using native species (Quercus brantii, Quercus infectoria, Quercus libani, and Pistacia atlantica) in the destroyed stands.

Soil and vegetation are mutually influencing because of strong bilateral relations. Soil characteristics can be different depending on the density of vegetation and the type of land use. Since the long-term stability of forest ecosystems is dependent on maintaining the quality of the soil, knowing the condition of the soil in forest areas and investigating the effects of various activities on the soil properties is very important and effective in forest management. Therefore, in this research, we investigated and studied the effects of intensive Thinning operations on some soil components in a Coppice stand and young Sprout-Clumps of Quercus brantii Lindl. species in Rikhlan forest (a forest site in Marivan). This area is an indicator of the degraded forests of North Zagros. this research was conducted in the form of complete randomized blocks in three treatments and three repetitions. The duration of the research was 8 years in two phases of 4 years. In addition to thinning treatments, soil samples were also prepared and analyzed from a depth of 0-15 cm of each treatment. The general conclusion is that thinning operations have long-term effects on some soil indices, and thinning with increasing intensity (18% of all Sprouts removed in the first 4 years and 22% of remaining Sprouts in the next 4 years) compared to thinning with The reducing intensity (32% of all Sprouts removed in the first 4 years and 28% of remaining Sprouts in the next 4 years) has caused the least stress on soil fertility indicators.

The Zagros forests vegetation area with an area of more than 5 million hectares and providing more than 40% of the country's water are ecologically very important and the forest covers 256000 hectares of Kurdistan province (8.8% of the province) and in recent years, Oak decline and decay have increase in these forests. Oak decline in the Zagros forests has started in the last two decades and has caused serious damage to the forests of this vegetation area and study of the effective and aggravating factors of Oak decline provides valuable information to natural resource managers. The factors of slope aspect and physical and chemical soil parameters can has an effect on the aggravation oak decline in this forest. The aim of this study was to investigate and compare the physical and chemical soil parameters in around healthy and dieback trees under the influence of slope and dieback in Marivan forests (in Kurdistan province).

Deteriorated (Garan) and control (Dolah Naw) stands were selected in the northern and southern slopes aspect. In the Garan habitat (Oak decline) on the northern slope, five healthy trees and five dieback trees were selected (10 trees in total), on the other hand, in this habitat on the southern slope, 10 more trees were selected (five healthy trees and five trees with dieback). In Dolah Naw habitat (control habitat), five healthy trees were selected in each aspect (in total, 10 trees in the control habitat). In total, 30 healthy and dieback trees were selected and numbered (20 healthy trees in the control and dieback trees and 10 trees in the dieback stands). Then, in the vicinity of the trunk of each tree (in the shaded part of the crown), a soil sample was taken at a depth of 0-20 cm (Horizon A) and the samples were transported to the laboratory in plastic bags. Physical and chemical characteristics (moisture percentage, acidity, soil electrical conductivity, absorbable phosphorus, absorbable potassium, nitrogen percentage, organic carbon percentage, lime, calcium and magnesium percentage) were measured for each soil sample. The two-way analysis of variance test was used to compare the effect of each factor and the interaction effect of the investigated factors on the physical and chemical parameters of the soil and data analysis was done in SPSS 20 software.

The one-way analysis of variance test showed that there was a significant difference between the parameters of pH, electrical conductivity, percentage of organic carbon, potassium, nitrogen, moisture, lime, magnesium and calcium among the soil samples of healthy and dieback trees in the northern and southern slopes. The results of the analysis of variance test confirmed the interaction effect of kind of stands × slope aspect for electrical conductivity and calcium and for slope aspect × tree health in the parameter was lime percentage. Other findings showed that the highest average parameters of electrical conductivity, available phosphorus, potassium, organic carbon, nitrogen, and moisture were respectively 2.654 (d s m-1), 1.10 (mg/kg), and 869.5 (mg/kg). ), 4.03%, 0.35% and 12.4% were observed in the soil adjacent to the control trees in the northern slope and for magnesium, calcium and CaCO3 parameters of healthy trees in the southern slope with the values ​​of 21 (meq/100), 42.2 (meq/100) and 13.60% was significantly more than other treatments. On the other hand, in the soil sample adjacent to the trees located in the stands affected by dieback, the average physical-chemical parameters were lower than the control stand (Doleh Naw) and this shows the importance of the physical-chemical parameters of the soil in reducing or increasing the resistance of trees to tree dieback. The findings of the research showed that the highest average macro elements (available phosphorus, potassium and nitrogen) in the soil adjacent to healthy trees in the northern slope and for calcium and magnesium, the highest amount of these elements were observed and confirmed in the soil adjacent to the trees in the southern slope and in the total amount Macro elements were more in the soil of the trees of control (north and south domain); Therefore, the physical and chemical characteristics of the soil (especially macro elements) have an effect on the resistance of oak trees to dieback and other environmental stresses, and the lack of macro elements causes the trees to be weak against the phenomenon of oak dieback.

In general, in the soil adjacent to the dieback trees, the poverty of nutrients and macro elements and lower values ​​of the studied parameters were observed. In general, in the trees affected by Oak decline, the poverty of nutrients and macro elements was observed, and the lower values ​​of the parameters were observed in the soil adjacent to the trees affected by Oak decline. Based on the results, for the optimal management of dieback stands and trees, increase protection measures (control of livestock grazing through grazing and reduction of traditional exploitations), increase restoration programs and forest development in the stands affected by dieback (increase seeding and enrichment operations). In degraded stands and planting with native species in dieback stands) and implementation of health cuts (withered and dieback branches and stems) were suggested.

Crown canopy is a major structural characteristic of forest trees and is vital to their ecological function. The present study investigated tree crown changes in Marivan County coppice forests. This research was conducted in two forest areas, Garan and Doleh Naw. First, five trees were selected for each habitat. The crown of each tree was photographed in the four main geographical directions one meter from the tree trunk. It was done in September 2021 and 2022. Tree canopy measurement in each image was done using MIP Cloud4 student software. Paired t-test was used to compare tree canopy percentages in two imaging periods. According to the results, the canopy of trees in Garan and Dolah Naw habitats in 2022, compared to 2021, increased by 9.02% and 11.51%, respectively. Meanwhile, in the habitats of Garan and Dolah Naw, the highest increase and change in the tree crown was observed on the southern and eastern sides of the tree crown. Also, from 2021 to 2022, the weather conditions improved. Dolah-Naw habitat trees had slightly larger average parameters than the Garan habitat. Irrigation of degraded areas (with increasing tree crowning) is crucial for sustainable management due to the importance of tree crown canopy in forest stand functions.

In order to properly manage the forest, we need tools that can be used to study the changes in the forest structure. In this research, the structure of degraded oak forests of Piranshahr and Sardasht in West Azerbaijan province were investigated. Characteristics of the stand were investigated in two one-hectare sample plot with dimensions of 100 x 100 meters in two different forest types, including Darsarvin Sardasht (30% canopy cover, coppice with standard) and Piranshahr Pardanan (90% canopy cover and all of trees were of coppice). Using 100% inventory and a set of indices based on the nearest neighbor, three characteristics of location, mixture and dimensions of trees were investigated.

The investigation of the structure was done by using the indices of density, diameter, height, basal area and trees location. As well as the indices based on the nearest neighbor in two sample plots were used. The structural variables of all the trees in the sample plot were measured separately for coppice and standard trees. The characteristics of the species, spatial coordinates, diameter at the height of 0.5 meters of the trunk, and height of all trees were measured. Three criteria of species density, basal area and canopy cover were also used for forest typology. To describe and quantify the structural features of forest stands in this research, indices based on the nearest neighbor were used. For this purpose, distance to neighbors, uniform angle, Clark and Evans, Mingling, DBH differentiation and CC differentiation were used. The calculations related to the structural characteristics of the examined stands were done using SPSS version 20 software and the calculations related to the structural indices were done using the Crancod software set (ver 1.3).

The Clarke and Evans index with values of 0.82 and 0.94 for Darsarvin and Pardanan, and uniform angle with values of 0.56 and 0.52, respectively, showed a cluster distribution pattern and random species distribution pattern in both stands. Mingling index shows that there is more mixture of neighboring trees in Pardanan (0.65) than in Darsarvin (0.38). The diameter difference index shows a greater difference in the half-meter trunk diameter of Pardanan (0.55) compared to Darsarvin (0.46). But the canopy differentiation index shows a greater difference in the canopy cover of Darsarvin (0.58) than in Pardanan stand (0.53). The results of the combined diversity index showed that the structural diversity in Pardanan (0.41) is higher than Darsarvin (0.36). This index shows that there is a low level of combined spatial, species and dimensional diversity in the two stands. Results are consistent with the situation of the two regions that are affected by destructive factors and limited regeneration. These results can be used for comparing structural characteristics of forests and determining the impact of human intervention.

The results of the composite diversity index showed that there is a low level of spatial, species and dimensional composite diversity in the two forest stands, and these results are consistent with the influence of destructive factors as well as the limitation of regeneration. Considering the difference in the stands in the two sample plots in this investigation, the results of these indices can be used as a basis for comparison with other similar forests and determining the amount of deviations caused by natural processes and human interventions. Also, it seems necessary to achieve a suitable management model and Silviculture practices in the forests of this region and determine the structure and planning based on the current situation using these indicators.

This research was designed to investigate the dieback of oak (Quercus infectoria; Q. libani) trees in the northern Zagros forests in West Azerbaijan Province. Characteristics of the stand were investigated in a one-hectare sample plot with dimensions of 100 × 100 meters. To monitor dieback, inside the sample, a sub-plot with a floating surface was determined where 100 oak trees could be placed. The dieback was monitored over four years (2019-2022) using a five-level scale: 1) healthy, 2) dieback, 3) crown dieback up to 50%, 4) crown dieback exceeding 50%, and 5) tree cut down. The results showed a decrease in the number of healthy trees from 94% to 71% between 2019 and 2022, with 9% of trees ultimately being cut down. To investigate the relationship between leaf surface and the dimensions and weight of seeds of trees, 20 leaves were selected from five permanent trees, and their surface was calculated annually for three years (2019-2021). Additionally, 25 seeds were harvested, and the dimensions and weight of the seeds were determined annually. The results of calculating the average leaf area over three years showed a significant decreasing trend. Except for seed weight, other dimensions in the seed showed a significant decreasing trend during the monitoring years. Overall, the results showed that despite the absence of oak charcoal disease in the province, the trend of decreasing healthy trees and increasing trees with different levels of dieback is very worrying.

The Zagros forests are known as the second-largest forest ecosystems in the country in terms of surface area, and they provide many ecosystem services such as carbon storage. Soils are the largest reservoir of carbon storage in dry ecosystems. The purpose of this study was to investigate the carbon storage status of coppice oak stands (exclosure and non-protected stands). In this regard, two forest stands, Garan (an exclosure area) and Dolah Naw (a typical forest of Kurdistan province), were selected in Marivan county, Kurdistan province. A square sample plot of one hectare was considered randomly in each stand. In each plot, five soil samples were taken from a depth of 0-30 cm, and physico-chemical characteristics of the soil, microbial respiration, and organic carbon percentage were measured in the laboratory. Considering the normality of the data, the independent t-test was used to compare the averages of the study parameters in the two plots. The results showed that the percentage of organic carbon and carbon storage in the Garan, with values of 3.63% and 104.3 tons per hectare, respectively, was significantly higher than that of the Dolah Naw (with 2.63% and 86.7 tons per hectare). Additionally, the parameter values of gravel percentage, microbial respiration, and C/N ratio in the Garan (37.3%, 472.9 mg CO2/kg, and 13.1, respectively) were higher than those in the Dolah Naw. The general results of the research showed that carbon storage in the Garan stand (under protection management) exceeded that of the Dolah Naw. As a result, exclosure and forest protection increases the percentage of carbon storage and the amount of soil carbon storage.

One of the environmental problems of Zagros forests is oak decline, which is less intense in northern Zagros than in middle and southern Zagros. The purpose of this study was to investigate the oak decline in Baneh County (Kurdistan Province) in 2019, 2020, 2021, and 2022. In order to carry out this research, two plots (with 100 trees) were considered in Belveh (tree dieback–southern slope) and Saraki (tree dieback–northern slope) sites in Baneh County in the northwest of Kurdistan Province. In 2019, oak trees were numbered at the desired sites, and in October 2019, 2020, 2021, and 2022, oak decline classes (five classes) were recorded for each tree. The results showed that the number of healthy trees in the Saraki and Belveh sites decreased by 25 and 28 trees, respectively, from 2019 to 2022; in contrast, the number of dieback trees increased by 14 and 19 trees, respectively, and the intensity of oak decline was greater in the Belveh site (southern dieback stands) than in Saraki (northern dieback stands). In general, the decline rate in the southern stands was higher than that in the northern stands, and the highest oak decline was observed in the southern slope. To optimally manage these forests, it is necessary to manage the factors that exacerbate oak decline and to control human interference and forest destruction so that the current situation is fixed and the seeds of healthy stands on the northern slopes are used for the regeneration and development of the forest.

One of the environmental problems of the Zagros forests, is the occurrence of oak decline phenomenon in Zagros Forest. The intensity of oak decline in the North Zagros is slower than in the Middle and South Zagros. The purpose of this study was to investigate the trends of oak decline in forests of Baneh city from 2019 to 2020.Four sites including Belveh and Gandman (southern aspect) and Saraki and Mirhesam (northern aspect) were selected and 100 trees were evaluated in each site. Oak decline status was recorded during two years of research in five classes: healthy trees, dieback in crwon, dieback up to 50%, dieback more than 50% and standing dead tree. Wilcoxon and Friedman (non-parametric tests) were used to compare the decline codes at each site for two consecutive years and to compare the decline codes at four sites per year (separately). The results showed that the greatest change of oak decline class was in Saraki site (with 0.27 change). At all four sites, the trees were shifting to oak decline classes in the second year of the research, and the change in oak decline classes at each site for two consecutive years (Wilcoxon test) was statistically significant. Besides, the change of dieback trees (dieback and dieback up to 50%) from 24% of trees in 2019 to 44% of trees in 2020 had changed. Most oak decline was observed on the southern aspect. Overall, it is suggested that human intervention be controlled.

In this study, the structure of Zagros forest stands was analyzed using neighborhood-based indices such as Clark and Evans, uniform angle, mingling, diversity of dimensions, diversity of combined structure, and distance to the nearest neighbor in two one-hectare (unprotected) sample plots in Chaharzebar and Barzeh forest areas (as a sample of the majority of Kermanshah province's forests). Clark and Evans index values of 0.87 and 0.88 for quadrupeds and ridges, respectively, and uniform angles of 0.51 and 0.5, respectively, revealed a spatial distribution pattern in both hilly areas and a species distribution pattern in random quadrants and the Barzeh region. The average mingling index values of 0.13 and 0.005 revealed that the Barzeh region had substantially lower species mixing than the Chaharzebar region. In addition, the mean diameters of differentiation indices with values of 0.55 and 0.38, and height differentiation with values of 0.2 and 0.19, were determined for Chaharzebar and Barzeh, respectively, indicating a minor height difference and the diametric superiority of Chaharzebar trees over Barzeh. In general, the structure of the forest in the analyzed regions has been significantly altered, and the findings of the hybrid diversity index revealed a low level of biological, species, and dimensional variety in the two studied forest stands.

Most macronutrient accumulation occurs in tree leaves and there is a strong relationship between leaf nutrient change and tree decline. The aim of this study was to investigate the changes in leaf nutrients in healthy and withered trees in the forests of Marivan and Sarvabad county in Kurdistan province. For this purpose, Garan (Marivan) with declining trees were selected as unhealthy site, while Dezli (Sarvabad) was determined as a control site containing heathy trees. In both sites, trees were selected on the northern and southern slopes, where five healthy trees and five withered trees (totally, 30 trees including 10 trees in control and 20 trees in declining stands) were selected and numbered. 20 leaves were harvested from the four sides of a tree crown in the first week of August 2019 and 2020. The concentrations of nitrogen (N), phosphorus (P) and potassium (K) were measured using digestion method. Due to the normality of the data, one-way analysis of variance, Duncan and paired t-test were used to analyze these data. The results showed that the amount of N in the decline site was higher than that in the control site. In contrast, leaf P and K contents in tress of control was significantly higher that decline stands. and potassium elements, the amount of these elements in the control mass was higher than the decaying mass and had drought. The highest reduction of N and P were observed in withered trees in the northern and southern slopes and one-way analysis of variance test confirmed the significance of the difference between K (2019) and P (2020) in the six groups of studied trees. On the other hand, changes in leaf nutrients between 2019 and 2020 demonstrated a decreasing trend for N and P and an increasing trend for K, where the paired t-test confirmed the significant change in nutrients of tree leaves in two consecutive years. To improve P and K in decline trees, foliar application of these macronutrients could be suggested in a short-time period, and in the long run, susceptible ecosystems should be rehabilitated by reforestation with rainwater catchment system and protection systems.

Oak mortality is one of the most important management problems in the Zagros forests and the first signs of oak mortality appear in the canopy of trees. The aim of this study was to investigate the trend of oak mortality in trees with different crown-dimensions in the forests of Baneh County (northwest of Kurdistan province). For this study, four sites in the northern slopes (Saraki and Mirhesam sites) and southern (Belveh and Gandman sites) in Baneh county were selected. At each site, floating sample plots (with 100 trees) were selected and the trees were numbered and measured (two large and small diameters of tree crowns). The crowns of the trees were divided into eight classes. At the end of summer of every year (2019 and 2020), the status of trees in the five oak mortality class was reviewed and recorded. The weighted average of decay codes was used to compare the rate of decline in two consecutive years and Wilcoxon non-parametric test was used to compare the decline codes in the crown area classes in two consecutive years. The results of Wilcoxon test showed that in the four sites studied, there was a significant difference between the decline codes from 2019 to 2020. At Sarki and Belveh sites (oak mortality site), the most oak mortality was observed in the crown and 11 and 17 m2 crown classes. In control sites (Mirhesam and Gandman), the highest increase of oak mortality trees was observed in the 5 and 11 m2 crown classes. The results of oak mortality weight of four stands, showed that the highest increase in oak mortality was observed in the 11 m2 crown classes of Sarki site (with 0.67 increase) and 5 m2 classes in Belveh (with 0.33 increase, respectively) and the highest oak mortality in the southern slope. In order to manage forest stands in the study area, it is suggested to focus the breeding operation and remove the dried branches on small to medium-sized trees (trees with a canopy up to 25 m2) and the decay trend of oak trees in the study area be monitored.