فصلنامه تحقیقات جنگل و صنوبر ایران
سال سی و یکم شماره 3 (پیاپی 93، پاییز 1402)

In light of projections indicating a growing demand for wood in the forthcoming years and the initiation of a plan to cease the exploitation of the Hyrcanian forests from 2019, the inadequacy of wood essential for the country's wood industry has emerged as a paramount challenge. The escalation in the exchange rate has rendered wood imports insufficient to cater to the nation's entire needs, underscoring the imperative to elevate wood cultivation levels as a primary solution. Despite the relatively modest expanse of poplar plantations and wood cultivation in Kurdistan province, the conducive conditions of ample rainfall and the presence of numerous seasonal and permanent rivers render it a viable area for expansion. Consequently, it becomes crucial to identify and effectively manage the obstacles and challenges impeding the development of wood cultivation in Kurdistan province.

This study focused on wood plantations and management strategies in Kurdistan province. A comprehensive questionnaire, encompassing the strengths, weaknesses, opportunities, and threats related to the development of wood farming in Kurdistan province, was meticulously prepared and finalized. The geographical boundaries of Kurdistan province served as the system's perimeter for the identification and categorization of these four key components. Employing purposeful sampling, experts well-versed in the research topic were deliberately chosen for their valuable insights. A total of 60 informed experts and local stakeholders, determined in accordance with Cochran's formula with a 10% error rate, actively participated in the review and scoring of the SWOT analysis questionnaire for wood farming in Kurdistan province, utilizing a Likert scale ranging from 1 to 5 points. The collected data, including the questionnaire results and SWAT analysis scores, were meticulously entered into an Excel program. Subsequently, total points for each item were calculated, followed by the determination of averages and relative weights for each of the four subsections of the SWAT analysis. Building on the average scores for strengths and weaknesses (internal organization) as well as opportunities and threats (external organization), the management strategy was discerned through the utilization of the Space Matrix and Strategic Action tools for wood farming in the province. This determined management strategy served as the foundation for the development of strategic plans spanning a period of 10 to 15 years, meticulously crafted to optimize wood farming in Kurdistan province.

According to the research findings, there are 16 strengths, 22 weaknesses, 15 opportunities, and 8 threats identified for the development of wood farming in Kurdistan province. The results highlight the most significant strength and opportunity for wood farming development in Kurdistan: "3000 kilometers of seasonal and permanent rivers in the province" and "the increasing demand from wood and paper industries for wood raw materials," respectively. Conversely, the most critical weakness and threat for wood farming in the province are identified as the "long harvest period of wood (economic age over 8 years) and the lack of income during this period" and "climate change leading to a reduction in annual rainfall and surface water." Local stakeholders emphasized that "the increase in demand for wood in other Iranian provinces (due to the lack of conversion industries in Kurdistan province)" stands out as a pivotal opportunity for the development of wood farming. Based on these findings, the conservative strategy (with a position of -19.67; 25.14) was endorsed in the second quarter of the coordinate system. Consequently, four long-term programs were formulated to optimize wood farming development in Kurdistan province: 1) Ensuring the annual pre-purchase of wood from farmers, 2) providing support and allocating facilities for the development of wood cultivation in the province, 3) promoting wood farming and increasing community participation, and 4) enhancing the province's infrastructure and fostering the growth of wood-related industries.

Recognizing the crucial significance of advancing wood farming in Kurdistan province, it is imperative to underscore and strategically plan the following short-term initiatives: 1- Construction of a Wood Industry Factory, 2- Cooperative and Local Organization Engagement, 3- Technical Involvement of Natural Resources Experts, 4- Formation of Trade Union Cooperatives, 5- Guaranteed Wood Purchase Opportunities, 6- Wood Farming Festival, and 7- Infrastructure Enhancement and Industry Development.

Given the significance of fine woody debris (FWDs) in the context of the carbon cycle, climate change, and its implications for renewable energy and economic development, it is imperative to obtain accurate information on the dispersion of FWDs volume stock for effective management of Hyrcanian forests in Iran.

This study was conducted in the Kheiroud forest in Nowshahr county, Iran, employing cluster sample plots distributed along the altitude range of 100-1815 meters above sea level (m.a.s.l.). Circular sample plots were established within each cluster, employing a line transect with a constant azimuth of 150 degrees and a radius length of 7.32 meters. Three diameter classes (1-2.5 cm, 2.5-4.5 cm, and 4.5-7.5 cm) were measured based on line-intersected fallen woods. The coordinates of the samples were recorded, and kriging and inverse distance weighted (IDW) methods were utilized to elucidate the autocorrelation of FWDs volume stock. Stand type, aspect variations, and altitudinal range were considered as main factors in the multiple-way ANOVA.

The findings revealed that the mean FWDs volume stock for each diameter class was 2.14, 6.01, and 16.23 m3/ha in the studied forest. Notably, fluctuations in the FWDs at the third diameter class were less pronounced than in other diameter classes. The goodness of fit data between observations and estimations indicated that both Kriging and IDW techniques estimated responses with low accuracy (R2 = 0.16; RMSE = 6.32) and no accuracy (R2 = 0.04; RMSE = 21.17; R2 = 0.03; RMSE = 37.11). Geostatistical techniques demonstrated that FWDs volume stock cannot be considered a regional variable, lacking autocorrelation and spatial correlation. Consequently, ANOVA results, based on observed power and partial eta squared, revealed that the interaction of altitude, stand type, and aspect did not significantly influence variations in FWDs volume stock (P > 0.05). Pairwise comparisons based on the LSD test indicated that the marginal mean of FWDs in the first diameter class was significantly different only along the altitude (P < 0.05).

In conclusion, the observed variation in FWDs volume stock at different diameter classes appears to be random and independent of the considered interactions. However, complex ecological and biological factors likely contribute to the dispersion of FWDs volume stock in the studied forest.

Riparian forest ecosystems play a crucial role in maintaining ecological resilience and biodiversity in hot and arid regions. Additionally, these forests serve as vital safeguards against agricultural land erosion and alterations in riverbeds. Long-term monitoring is imperative to preserve the ecological capacity and biodiversity of riparian forests, which are continually impacted by climate change and land use/cover changes (LUCC). These changes have far-reaching implications for the environment, biodiversity, food security, and human health.

This study utilized the Landsat satellite series archive for Gotvand County in Iran. The analysis commenced with an image from the MSS sensor (Landsat 1) in 1972, followed by images from the TM, ETM+, and OLI sensors placed in orbit on 7/16/1982, 4/15/1999, and 11/2/2013, respectively. Raw calibrated pixel values underwent conversion to surface reflectance through atmospheric correction. Classification input layers included spectral bands and two indices (NDVI, SAVI for vegetation cover, and MNWDI, NDWI2 for water class), derived from available spectral bands for each year. Object-based classification, employing the SVM algorithm, was implemented to extract forest areas, water bodies, agricultural lands, and other phenomena. Various values for scale, shape, and compression were applied in the object-based classification method to enhance separation. Evaluation metrics such as Overall Accuracy, Producer’s Accuracy, User’s Accuracy, and Kappa Coefficient were employed to assess classification results.

The study observed the lowest difference between Red and NIR bands for the MSS sensor and the highest difference for the ETM+ sensor. Classification accuracy was lower for years when ground sample conditions were validated through satellite images compared to other years. In 2022, with improved spatial and spectral accuracy, the overall accuracy reached 98.9%, the Kappa coefficient was 0.89, and user and producer accuracies for the forest class were 97% and 99%, respectively. Agricultural land changes witnessed a staggering growth of over 4393% from 1972 to 2022. Riparian forest ecosystems, dominant in the area between 1972 and 2000 (ranging from 3670.6 to 2379.2 hectares), experienced a 35% loss. From 2000 to 2022 (covering 1569.6 hectares), an additional 34% of this plant ecosystem's area was lost.

The research findings highlight a 57.23% decrease in riparian forests over the past fifty years, reaching its lowest point of 1279.2 hectares in 2010. Concurrently, agricultural land area expanded by 45 times from 1972 to 2022, indicating a significant shift in land cover from forests to agriculture. The observed changes align with shifting precipitation (-1.5 mm/yr) and temperature (0.04 °C/yr) trends, impacting the studied ecosystems. This study serves as a crucial benchmark for the sustainable management of riparian forests along the Karun River in Gotvand County.

Botanical gardens play a pivotal role in preserving native species, a challenging task in the autumn season when identifying leafless plants, particularly in the rose family (Rosaceae), becomes challenging. Propagation through cuttings offers a solution to maintain plant diversity. However, in humid climates, the main hurdle in plant propagation is combating pests and diseases. This research aimed to explore similar bases of Rosaceae wild species as rootstocks through cutting propagation, coupled with nematode control.

Conducted in the nursery section of Nowshahr Botanical Garden, Iran, from autumn 2019 to March 2021, this research employed a four-factorial experiment using a completely randomized design on four Rosaceae species: forest apple (Malus orientalis Uglitzk. ex Juz.), Mazanderani pear (Pyrus mazanderanica Schonb.-Tem.), prickly forest plum (Prunus spinosa L.), and thornless forest plum (P. divaricata Ledeb.). Factors included dipping cuttings in willow extract (zero, five seconds, and 24 hours) and feeding cuttings with a nutrient solution containing garlic extract (zero, 10%, and 20%). Cuttings were sourced from Rosaceae species in Hyrcanian forests. Willow extract, derived from one-year-old willow tree branches (Salix alba L.), and garlic extract from garlic species (Allium sativum L.) scales were utilized. Changes in nematode populations were monitored through soil and root sampling every 5 months for 18 months, with microscopic observations determining nematode infestation of Meloidogyne sp. and Pratylenchus sp. species.

Significant differences were observed among species concerning root formation, vegetative bud growth in cuttings, egg mass nematode density in one gram of root, and nematode density in 200 grams of soil. In forest apple, the 24-hour treatment of cutting tip dip in willow extract yielded the highest number of sprouts, roots, and fresh root weight. The lowest nematode density was recorded at 20% garlic extract. For Mazandarani pear, the 24-hour willow extract treatment resulted in the highest wet and dry root weights. Prickly and thornless forest plums exhibited optimal growth in the 24-hour willow extract treatment. Interaction effects of willow and garlic extracts on nematode populations in soil indicated the lowest density in 20% garlic extract with a 24-hour willow extract soak for forest plum species.

Willow and garlic extracts proved effective in stimulating rooting in cuttings and soil disinfection, enhancing rooting and soil health by reducing nematode contamination. Thornless plum species exhibited the highest root formation and vegetative growth with minimal nematode contamination. Conversely, forest apple and Mazandarani pear did not exhibit a significant response to the interaction effects of plant extracts.

The presence of trees of varying sizes contributes to the creation of diverse and complex forest structures. However, human disturbances can disrupt these structures and negatively impact tree size diversity. This study investigates the effects of human disturbances on tree size diversity in the Arasbaran forests of northwestern Iran. The findings provide valuable insights for managing existing forests under population pressure and diverse land uses, as well as for developing conservation measures that optimize the utilization of limited forest resources.

To assess the impact of human disturbances, three areas with varying disturbance levels were selected based on forest history, observations, and proximity to the primary disturbance source. Within each area, four 1-hectare (100 × 100 m²) sample plots were established. A census of all trees and shrubs was conducted, and their diameter at breast height (DBH; ≥5 cm), height, and species number per hectare were recorded. Tree size characteristics in these areas were quantified using the plotless nearest neighbor method. Three transects were laid parallel and perpendicular to the secondary road in each area, with samples taken at regular 25-meter intervals. Using random-systematic selection, the nearest tree to the sample line was selected as a reference tree, and four neighboring trees were identified. DBH, height, and tree-to-tree distance were measured for each tree. Tree size diversity was analyzed using indices including distance from the nearest neighbor, diameter mean and coefficient of variation, diameter differentiation, height differentiation, Gini coefficient, and Shannon index of tree size diversity. Pearson's correlation test was used to determine the correlation between each tree size diversity index and the disturbance intensity index in the region.

 An average of 399 trees and shrubs were recorded per hectare in the study area, with the highest density observed in the low disturbance area. Mean diameter and total tree height were higher in the high disturbance area compared to the low and medium disturbance areas. The distance index from the nearest neighbor was significantly higher in the high disturbance area compared to the other two areas (F=41.49, sig<0.001). The coefficient of diameter variation was also significantly higher in the low disturbance area compared to the other two areas (F=17.11, sig<0.001). There was a significant negative correlation (r=-0.682, sig<0.001) between the coefficient of diameter variations and the disturbance intensity index. Average DBH was higher in the high disturbance area, but the difference between the three areas was not significant (F=1.06, sig=0.356). The Gini coefficient index was significantly higher in the low disturbance area compared to the other two areas (F=17.89, si <0.001). Tree diameter differentiation was also significantly higher in the low disturbance area compared to the other two areas (F=13.86, sig<0.001).

Human disturbances negatively impact tree size diversity and forest stand structure, leading to reduced structural complexity. Mitigation strategies and protection plans are recommended to address human-caused disturbances in areas lacking size diversity. Planting pioneer trees can enrich structural complexity. Additionally, a conservation plan tailored to habitat conditions is required to promote size diversity and enhance forest resilience. Local organizations should prioritize this plan.

Soil bioengineering techniques offer multifaceted benefits and find applications across diverse landscapes. These approaches are notable for their high sustainability, adaptability to environmental changes, and effective reestablishment. While existing bioengineering studies focus largely on assessing root systems for soil stabilization, it remains pivotal to estimate key biotechnical characteristics, such as root distribution and mechanical strength, for various plant species. These insights serve as crucial inputs for developing robust soil reinforcement models. Root system distribution and mechanical strength data are integral for accurate reinforcement estimation. In Iran, conventional methods such as profile trenching and soil core sampling were employed for destructive sampling to investigate root system distribution and density. This focused on several tree species, including Fagus orientalis Lipsky, Carpinus betulus L., Alnus glutinosa (L.) Gaertn., Acer velutinum Boiss., Quercus castaneifolia C.A.Mey., Parrotia persica (DC.) C.A.Mey., Fraxinus excelsior L., Picea abies (L.) H.Karst., Quercus brantii Lindl., Quercus libani Oliv., Haloxylon persicum Bunge ex Boiss. & Buhse, Salix alba L., Tamarix hispida Willd., and Avicennia marina (Forssk.) Vierh. The mechanical properties of root samples from various species and habitats were investigated in a laboratory setting using a universal device. A novel in-situ pullout device with a 10-kilonewton capacity was employed in Iran to measure mechanical resistance in mangrove forests. Findings indicated that the mean root area ratio, a density indicator, ranged from 0.15% to 2.6%. Various factors significantly influenced root area ratio values, including species, slope gradient, health status, human intervention, stress direction, altitude, trunk diameter, age, and horizontal and vertical distances from the trunk. Mechanical resistance values were impacted by factors such as health status, pollarding, slope gradient, wind direction, season, altitude, age, and trunk diameter. Generally, higher slope gradients, trunk diameters, elevations, and ages increased root density, while diseases, pests, and pollarding treatments decreased it. Mechanical resistance values varied with factors such as season, trunk diameter, elevation, and the presence of stressors like slope and prevailing wind. In Iran, mean tensile force, tensile strength, and pullout resistance ranged between 17-145 N, 3-45 MPa, and 1.19 kN, respectively. Iran possesses essential data for applying classical models of soil reinforcement across various plant species. To enhance models, the use of in-situ pullout apparatus for assessing root mechanical characteristics in their natural environment is recommended. Despite the wealth of Iranian bioengineering literature, knowledge gaps persist, particularly in root architecture, distribution, and density, with a need for data on whole tree extraction and the development of allometric models for soil bioengineering applications.