مجله جنگل ایران
سال پانزدهم شماره 3 (پاییز 1402)

The beech tree has the ability to produce shoots and form a coppice stands under specific natural climatic and environmental conditions or under unusual circumstances caused by human interference. The current research aims to compare the structural characteristics of coppice and standard stands of beech in the Hyrcanian forests in the Chetan area in Nowshahr. The diameter at breast height of all trees was measured using the full calipering method to determine the stocking volume. Half-hectare sample plots were established using the distance-azimuth method to study the spatial structure. The standing and log stocking volumes were also determined. According to the results, the number of live and dead trees in the coppice stand was 174 and 9.7 per hectare, respectively, and their volume was 146.2 and 3.6 m³/ha, respectively. In the standard stand, the number of live and dead beech individuals was 145 and 11 per hectare, respectively, while their volume was 147.5 and 12.1 m³/ha, respectively. About 55% of the standing dead trees in the coppice stand and 35% of the standing dead trees and 42% of the fallen dead trees in the standard stand were primarily in the first decay degree. The highest number of individuals in a beech coppice group included four, which is 17%. Groups of five individuals and two individuals also accounted for 16.9% and 16.5%, respectively. Spatial structure indices of beech coppice, including the Pielou segregation, Clark and Evans, Mingling, DBH differentiation, DBH dominance, and uniform angle, indicate species continuity, clustering, severe dominance of beech species, moderate differences, small size dominance, and clump distribution, respectively. Traditional uses of forests have influenced the structural characteristics of beech stands. Therefore, it is suggested that these and other similar stands be protected as a forest reserve to ensure the development of these habitats towards a more favorable state and the stability of the landscape in these areas.

This research was designed and implemented with the aim of gauging the perceptions and views of forest-dwelling communities regarding the implementation of the Zagros Forest Resources Management Plan. Field surveys and interviews were conducted with heads of 82 households from local communities in the Bazoft region of Chaharmahal and Bakhtiari province, who were directly involved with the forest resources management plan. The study examined and prioritized the opinions of local communities on 24 indicators and three criteria: social-participatory, economic-livelihood, and forest management. The results revealed that among the evaluated indicators, people's satisfaction with the plan's implementation, the plan's responsiveness to the needs of local communities, and the improvement of household income after the plan's implementation were the least desirable. The criteria of forest management, economic-livelihood, and social-participation were prioritized from first to third, respectively. This confirms that the impact of the forest resources management plan on social and especially economic indicators was much less than on the forest management indicators. In fact, from the perspective of local communities, the economic and social outcomes of the plan have not been on par with its forestry effects. This has undoubtedly undermined the plan's effectiveness on forest management indicators. The study's findings underscore the need for special attention to the definition and effectiveness of socioeconomic indicators in the preparation of forestry and forest management plans. These indicators will influence all aspects of management in the forest and could potentially marginalize conservation, revitalization, and optimal utilization methods, leading to the loss of years of cost and investment.

The study of soil property variability over time in forest stands to determine the optimal age range for various management purposes is a research topic that has received limited attention in Iran. This research aimed to investigate the changes in soil carbon storage according to age in reforested stands of Acer velutinum in the Neka-Zalemroud forests. Three age groups were selected: 10-20, 20-30, and 30-40 years. Statistical analysis was conducted using 20 × 20 m sample plots and a systematic-random method with 50 × 50 m grid dimensions. Five soil samples (in the center and square of the sample plot) were taken from the surface soil (0-15 cm) in each age class studied. The results showed that among the physical characteristics, the highest soil moisture (37.33%) was found in the 30-40 year age group, and the highest bulk density  (2.17 grams per cubic centimeter) was found in the 10-20 year age group. Upon examining the chemical characteristics of the soil, it was found that apart from acidity and electrical conductivity, the rest of the characteristics had significant differences influenced by the age of the stand. The highest amounts of absorbable phosphorus (7.81 mg/kg), total nitrogen (0.35%), and organic carbon (6.1%) were found in the 30-40 year old stand, and the highest amount of absorbable potassium (638.91 mg/kg) was found in the 10-20 year old stand. The carbon sequestration study showed that the 30-40-year-old stand had the greatest ability among the stands, with 305.89 tons of carbon sequestered per hectare. Therefore, based on the optimal age of carbon storage (30-40 years) for reforested Acer velutinum, the results of this research can be prescribed for different management purposes.

Parrotia persica, a native species of the Hyrcanian forests, is distributed from the west to the east of the forests of northern Iran. This study investigated the genetic diversity of Parrotia persica using molecular information from populations collected from three habitats in Gilan, four habitats in Mazandaran, and three habitats in Golestan. Using the Amplified Fragment Length Polymorphism (AFLP) marker, 826 bands were obtained, with more than 90% of the bands being polymorphic. The mean content of polymorphic information (PIC) and marker index (MI) were calculated to be 0.24 and 22.4, respectively. Cluster analysis based on the Jaccard similarity coefficient and Unweighted Pair Group Method with Arithmetic Mean (UPGMA) algorithm revealed a wide variety in the collected samples. Based on the Jaccard similarity coefficient, the range of genetic similarity varied from 0.26 to 0.44. The results of the molecular analysis of variance (AMOVA) showed that 21% of the total genetic diversity in Parrotia persica populations was due to genetic diversity between the populations of the three provinces of Golestan, Mazandaran, and Guilan. Genetic diversity within the populations of the habitats accounted for 79%. It can be concluded that there is no difference between the populations based on the diversity of molecular information, but there is diversity within the populations. The diversity among the evangelical populations seems to be more influenced by the environment than genetically. However, for a more accurate conclusion, it is suggested that different ecotones of the population be examined with molecular markers.

In this study, the capability of single-polarized TanDEM-X data was assessed for estimating the Hyrcanian forest height. Two approaches of Sinc interferometric coherence model based on Random Volume over Ground (RVoG) and differential interferometry utilizing airborne LiDAR-derived DTM were compared. The study was conducted in part of Dr. Bahram Nia’s forest management plan (Shast-Kalateh). 308 circular sample plots with an area of 0.1 ha were used in evaluating the accuracy of predicted forest height using two different approaches. For this reason, Lorey’s mean tree height weighted by basal area was calculated. The interferometric coherency was involved in the Sinc function for inverting forest height. We also removed topography from the SAR phase calibrated with LiDAR-derived DTM on open areas for estimating forest height based on differential interferometry. After terrain correction, the average predicted canopy height was extracted for each plot. Our results showed higher accuracy of differential interferometry than the Sinc model in forest height estimation when compared with ground reference data (RMSE=2.86 m and rRMSE=12.28%). Although, the accuracy of estimated forest height by the Sinc model was comparable with RMSE=3.41 m and rRMSE=14.46%. We found TanDEM-X data and coherence-based models a relatively promising approach in the Hyrcanian forest even though only 15% of Lorey’s men height change was explained by the Sinc model. Hence, further studies are needed to figure out the effects of species, slope, and image aquisition features on the results.

Forest roads are recognized as one of the primary sources of sediment production in mountainous watersheds. Predicting the amount of sediment they produce is crucial for effective management. The WARSEM model, developed in the forests of the United States and used globally, is one of the most efficient models for estimating sediment from forest roads. However, a significant limitation of this model is the lack of fillslope data. Given the unique characteristics of the northern forests of Iran, such as steep slopes, this study investigated the potential impact of this factor on the model's results. The study was conducted in the third district of the Chelavand forestry project, located in the natural resources area of Astara city in Northwestern Iran. The total length of the roads studied was 5.5 km, divided into 48 samples with homogeneous characteristics. Essential information was collected for the implementation of the model. The model estimated the amount of road and cutslope sediment to be 94.786 tons per kilometer per year. After incorporating information about the fillslope area, the model was run again. The predicted amount of sediment from the fillslope area was 3.4 tons/km per year. A t-test analysis revealed that the observed difference between the results was not significant. Therefore, it can be concluded that adding features related to the fillslope area does not significantly affect the final results of the model in the study area.

Oak forests in the Zagros region are under continuous anthropogenic disturbances, leading to a decline in their extent and deterioration in the qualitative structure of the stands. Field-based models can predict shifts in forest structure indices due to disturbance long before forest cover is depleted. This study examines the effects of anthropogenic land uses on key structure indices of oak forests in the Central Zagros.

Forest stand structure indices in five land uses were measured by field survey on 78 sample plots in 11 forests over an area of about 24,000 ha in the rural area of Mashayekh, Central Zagros. Depending on the area, six to nine systematically randomly designated one-hectare plots were measured at the same distance in each forest. In addition, one-meter square plots were sampled for non-tree cover. One-way ANOVA and General Linear Models were used to determine discriminant indices and analyze the effects of anthropogenic disturbance, respectively.

Except for oak density, structural indices differed significantly among the studied stands. This study did not find any differences in cover, number of trees, and non-tree species under different levels of disturbance (protection and destruction). The average number of shoots per stool decreased with increasing understory cultivation and proximity to villages, while the average diameter of shoots increased, indicating that farmers were removing young trees and shoots. Different levels of grazing and distance from the road had no effect on the structural index of the forest. The implementation of the conservation program in two forests in Kavand and Doto led only to an increase in the average height of trees and not to any other structural improvement.

Long before causing a reduction in forest area or a decrease in tree density, the effects of anthropogenic disturbance on the structure of coppiced woodlands were manifested in the diameter of trees and the number of shoots-per-stool. In addition, the decadal protection of the forest stands led to an increase in the average height of the trees. This suggests that the impact of anthropogenic disturbance on forest structure precedes the depletion of forest cover. Therefore, it is necessary to consider these early indicators in forest management plans.

The control and management of tourist impacts through the estimation of tourism carrying capacity is an effective strategy for preserving the values of recreational areas and promoting sustainable nature tourism development. This study aims to cquire management decisions to control tourist numbers and mitigate their threatening impacts on the mangrove forests of the Khamir and Qeshm area by estimating the nature tourism carrying capacity.

Given the conditions of the study area and its biological limitations, the carrying capacity was estimated in accordance with the framework of the IUCN guidelines (2003), across three levels: physical, real, and effective.

The results showed that the annual physical carrying capacity is equivalent to 29,088,095 tourists. Considering the climatic limitations and the impossibility of tourism activities in 7 months of the year, the actual carrying capacity was estimated to be 12,217,000 people. Tourists can visit this area or engage in compatible recreational activities during months with favorable climatic conditions (including December, January, February, March, and April). Finally, the effective carrying capacity in the mangrove forests of Khamir and Qeshm, based on the area size and the number of environmental guardians required to manage and control this area, is equal to 1,710,380 people per year.

According to the results, managers and decision-makers can protect and promote sustainable nature tourism development in this area by controlling the number of tourists. This ensures that while its tourism capabilities are being exploited, minimal destruction and damage are caused to these valuable natural reserves.