فصلنامه تحقیقات جنگل و صنوبر ایران
سال سی و دوم شماره 3 (پیاپی 97، پاییز 1403)

Protecting genetic and ecosystem diversity is essential for breeding programs and the development of new cultivars. The preservation of biodiversity in the Hyrcanian forests, often regarded as a living fossil, is particularly crucial. Cryopreservation, which involves storing biological samples in tanks filled with liquid nitrogen (LN), is the most effective long-term preservation method for plant genetic resources. It serves as an alternative to seed or in vitro banks and can be applied to both vegetatively and generatively propagated crops. Extremely low temperatures stabilize cells in their current state, allowing for long-term storage. This method incurs significantly lower costs compared to classical preservation techniques, while also offering extended sample protection. Various parts of the plant—including seeds, organs, callus, differentiated cells, meristem, and pollen—can be stored using cryopreservation. This technique protects samples from pests and diseases while requiring minimal energy and space for storage. Additionally, it allows for the replication of samples at low cost and with minimal facilities under any environmental conditions. Cryopreservation enables the collection and storage of plant species from diverse climates in one location under uniform conditions. This study aims to evaluate the feasibility of storing Acer cappadocicum Gled. seeds under cryopreservation conditions. To store A. cappadocicum seeds in LN, they undergo various treatments to prevent the crystallization of free water and rupture of the plasma membrane at cryopreservation temperatures. The seeds were subjected to chemical treatments—30% glycerol and a vitrification solution—along with a physical treatment to reduce seed moisture using a desiccator containing silica gel. These treatments aimed to enhance tolerance to drought and cryogenic processes. After 24 hours in liquid nitrogen, the treated seeds, along with control seeds, were thawed immediately at 42 degrees Celsius. To break dormancy, all seeds—including treated seeds, control seeds that had been cryopreserved, and control seeds that had not been exposed to liquid nitrogen—were planted in moist sand at a temperature of four degrees Celsius. Germination began after three months, followed by assessments of viability and germination rates. Each treatment included three replications with 25 seeds per replication. Data analysis was conducted using one-way ANOVA within a completely randomized design, with means compared using Duncan's multiple range test. Among the cryopreservation treatments applied to the seeds, physical dehydration yielded the highest germination percentage (26%) and seed vigor index compared to other treatments. Conversely, treatments with 30% glycerol and vitrification reduced germination rates for A. cappadocicum, suggesting sensitivity to these cryopreservatives that may harm the seed embryo. A significant difference was observed in root length and root-to-stem ratio among treatments; however, no significant differences were found in seedling length or stem length at the five percent level. In this research, seeds from three accessions of A. cappadocicum collected from different regions (Sari, Dehmian, and Kelich Kola) in Mazandaran province of Iran underwent physical dehydration treatment before being stored in LN tanks at the Research Institute of Forests and Rangelands in Tehran, Iran. This technology provides a viable method for conserving and protecting this species under critical conditions.

Salinity, caused by the accumulation of water-soluble salts in soil, is a major limiting factor for plant growth and development. A significant portion of Iran's soils are saline, which can severely restrict the cultivation of various poplar species. Therefore, determining the salinity tolerance of different poplar species can provide valuable guidance for poplar plantations in saline areas. This study investigates the morphological, physiological, and biochemical responses of Populus nigra L. clone “62/154” to varying levels of salinity stress. This high-yielding clone is widely used in poplar plantations across Iran. A pot study was conducted under controlled conditions using a completely randomized design to assess the morphological, physiological, and biochemical responses of this poplar clone to different salinity stress levels (0, 50, 100, 150, and 200 mM). Poplar cuttings were collected from the Alborz Research Center in Karaj, Iran, and planted in pots filled with clay-loam soil. The pots were placed outdoors during the experiment. The cuttings were initially irrigated with fresh water for three months before saline water (NaCl) was applied. After six weeks of salinity treatment, we measured survival rates, growth parameters, biomass production, relative water content (RWC) of leaves, macro- and micronutrient concentrations in plant tissues (leaf, stem, and root), and several physiological parameters (proline and sugar contents, malondialdehyde concentration, and enzyme activities). Data were analyzed using one-way analysis of variance to identify significant differences due to salinity treatment, with means separated by Tukey’s HSD test. The results indicated that poplar plants subjected to low salt stress (50 mM NaCl) exhibited no significant differences compared to control plants regarding survival, growth, biomass production, or physiological and biochemical parameters. However, at higher NaCl levels (100, 150, and 200 mM), soil salinity significantly reduced survival rates, growth parameters, biomass production, leaf RWC, and concentrations of nitrogen (N) and potassium (K) in plant tissues. Additionally, calcium (Ca) concentrations in roots and leaves decreased alongside magnesium (Mg) levels in leaves. Conversely, higher salinity increased leaf physiological parameters (proline and soluble sugar content), activity of antioxidant enzymes (CAT and POD), malondialdehyde concentration, as well as sodium (Na) and chloride (Cl) concentrations in plant tissues. Notably, phosphorus (P), iron (Fe), zinc (Zn), manganese (Mn), and copper (Cu) concentrations in roots and leaves also increased compared to control and 50 mM NaCl treatments. The most pronounced changes occurred at 150 and 200 mM NaCl. Overall, high salt levels (150 and 200 mM) led to a marked decrease in survival rates, growth, and biomass production along with significant morphophysiological and biochemical changes in the poplar plants. After six weeks of exposure to these salinity levels, survival rates dropped by nearly half. The observed decreases in survival rates, growth parameters, biomass production, changes in physiological parameters, nutrient absorption and accumulation in plant tissues—as well as higher accumulation of proline and sodium/chlorine elements—indicate that P. nigra clone 62/154 is salt-sensitive. Therefore, it is crucial to consider soil salinity levels and the sensitivity of this poplar clone when planning poplar plantation programs. Keywords: Black poplar, growth parameter, nutrients, proline, soil salinity.

Globally, paulownia (Paulownia fortunei (Seem.) Hemsl.) is one of the most important wood species used in forestry. Despite extensive research on this genus, the influence of climatic factors on the growth and anatomical wood properties of paulownia has not been thoroughly investigated. Therefore, this research aims to examine how climatic factors—such as temperature, precipitation, relative humidity, and sunshine hours—affect radial growth and specific wood anatomical traits of cultivated paulownia trees in Gorgan County, Golestan Province, Northwest Iran.

Five 20-year-old Paulownia fortunei trees were selected from Hashemabad in Gorgan County. These trees were felled in late 2012, and a five-centimeter-thick disk was extracted from each stem base. Strips from the bark to the pith were cut radially from each disk, and the surfaces of the specimens were smoothed using a microtome blade before scanning. To enhance the contrast between the vessels and the background tissue, a charcoal blackening technique was employed prior to scanning. Using images obtained from image processing software, several features were measured: growth ring width, average vessel lumen area, porosity, vessel frequency, vessel area greater than 0.06 mm², radial and tangential diameter of vessels, and ray frequency in each growth ring. To eliminate the effect of juvenile wood—which consists of very wide rings in the early years of growth—five rings near the pith were excluded from measurements and analyses. Consequently, growth rings from 1998 to 2012 (15 years) were evaluated. Pearson correlation was used to investigate the relationships between climatic variables (monthly, bimonthly, seasonal, bi-seasonal, and tri-seasonal) and growth variables (growth rate and quantitative anatomical wood characteristics) from three months prior to growth until the end of the growing season. Additionally, internal relationships among the measured variables were assessed similarly.

The radial growth of paulownia exhibited a decreasing trend with age, particularly notable at seven and thirteen years. Other anatomical features (vascular traits and ray frequency) showed an increasing trend; however, vessel frequency did not exhibit a clear age trend. Correlation analysis revealed that all anatomical characteristics had an inverse relationship with growth rate; thus, as growth ring width increased, other characteristics (e.g., vessel area and vessel diameter) decreased. Vascular traits and ray frequency primarily showed positive correlations with each other, while the correlation between vessel frequency and other variables was weaker. Among climatic factors, total monthly rainfall and average sunshine hours in spring (especially May and June) significantly impacted radial growth and anatomical features of paulownia wood. Climatic factors from three months prior to the growth period (the previous winter) did not show significant correlations with anatomical characteristics; furthermore, correlations between anatomical traits and summer climatic factors were much weaker than those observed in spring. Increased spring rainfall enhanced radial growth while reducing anatomical features such as vessel size and ray frequency; average sunshine hours had a similar but less intense effect on these traits. Temperature and air humidity did not significantly affect the studied characteristics.

Overall, it can be concluded that paulownia has high water and light requirements but shows low sensitivity to temperature in the studied region. The months of May and June (mid to late spring) are particularly influential for radial growth and hydraulic architecture (water transport system) in paulownia trees. Increased precipitation and average sunshine hours promote radial growth but reduce vessel size. Additionally, ray frequency can be considered a valuable wood anatomical characteristic for studying the relationship between climate and tree physiology in future research. 

When evaluating the sustainability of any subject, appropriate indicators must be selected and utilized. The functions and services of forest ecosystems serve as indicators of their capacity and effectiveness. Therefore, to align with fundamental policies regarding forest resources and to facilitate planning, decision-making, and success in this field, it is crucial to fully understand these capacities and effective indicators. This research aims to identify, weight, and prioritize the functions of Hyrcanian forests in Iran based on the Common International Classification of Ecosystem Services (CICES) method.

In this study, the functions, goods, and services of forest ecosystems were first extracted using the CICES method, which is recognized as one of the most comprehensive classification systems for ecosystem functions and services. Subsequently, the functions, goods, and services of Hyrcanian forests were identified through the Delphi method, incorporating insights from experts and specialists. Data were collected via field surveys, random sampling, questionnaires, and face-to-face interviews. The Delphi group comprised 50 experts in forest sciences with a minimum of five years of relevant experience who provided their opinions on the identification of functions, goods, and services related to Hyrcanian forest ecosystems. After preparing the questionnaire, respondents rated their answers using a five-point Likert scale. The reliability of the questionnaire was assessed using Cronbach's alpha coefficient, which yielded a value of α = 0.97, confirming its reliability. Following the completion of the questionnaires by experts, multi-criteria decision-making methods were employed to determine the weight of the functions, goods, and services of Hyrcanian forests. These methods included Step-Wise Weight Assessment Ratio Analysis (SWARA) for calculating function weights and Simple Additive Weighting (SAW), Additive Ratio Assessment (ARAS), and the Technique for Order of Preference by Similarity to Ideal Solution (TOPSIS) for prioritization.

Analysis of the questionnaire findings using the CICES method identified three functions and twenty services for the Hyrcanian forest ecosystem. Weighting results from the SWARA technique indicated that climate regulation, biodiversity, and genetic resources received the highest weights among the evaluated services. Additionally, the final weights derived from implementing gradual weighting evaluation techniques revealed that the regulating function (0.505) had the highest weight among all functions, followed by provisioning (0.248) and cultural (0.246) functions in subsequent priority order. Comparisons of prioritization among ARAS, TOPSIS, and SAW models showed similar results regarding function prioritization; however, the ARAS model exhibited a steeper slope in relative closeness to one compared to the other two models from various perspectives. Based on this finding and expert consensus, prioritization using the ARAS model was deemed more reflective of reality. Thus, the ARAS model is proposed as a suitable approach for prioritizing the functions, services, and goods of the Hyrcanian forest ecosystem.

According to results from the ARAS model, climate regulation, biodiversity, genetic resources, habitat services, and water cycle services rank as the first through fifth priority services within Hyrcanian forest ecosystems. Given the significance of regulating functions in these ecosystems and their beneficiaries, it is recommended that relevant organizations engage in more effective planning and management to ensure their protection and sustainability for present and future generations. Furthermore, maintaining ecosystem integrity is essential for promoting sustainable development while safeguarding environmental health.

Fine woody debris (FWD) is a significant reservoir of carbon and bioenergy in the Hyrcanian forests. Therefore, monitoring changes in FWD biomass on the forest floor is essential for sustainable management, particularly concerning carbon dioxide emissions and carbon trading in both international and domestic markets. The primary objective of this research is to develop optimal allometric equations for accurately monitoring FWD in one of the beech (Fagus orientalis Lipsky) communities within the Hyrcanian forests of Iran.

This study was conducted in the Shastkolateh research forest in Gorgan County, Iran. A random stratified method was employed for direct sampling and weighing of FWD. The FWD was categorized into three diameter classes: 1-2.5 cm, 2.5-4.5 cm, and 4.5-7.5 cm. For each diameter class, length and degree of decay were measured randomly in pure beech and mixed beech stands. Total weight was measured destructively using digital scales. To estimate biomass values of FWD, a power function allometric model based on curve estimation analysis was utilized. The middle diameter, length, dry wood density, and degree of decay of the weighed FWD were introduced as explanatory variables in the model input matrix. These explanatory variables were combined in various ways as independent variables in a log-transformed model. Model validation was conducted using adjusted regression coefficients (Adj.R²), variance inflation factors (VIF), and residual mean square (RMS). A t-test evaluated the significance of parameters in each model, while the fitting of a Loess curve between standardized residuals and estimations was used to assess the validity of the models.

Model development indicated that incorporating middle diameter (D) and length (L) of FWDs into the exponential function of the log-transformed model increased variance explanation from 38% to 73% and reduced RMS from 0.6 to 0.26. Adding wood density (ρ) did not significantly enhance model accuracy or validity. Including degree of decay as a dummy variable slightly improved model accuracy, resulting in the top-ranked model with the highest variance explanation (Adj.R² = 0.78) and lowest RMS (0.22). Furthermore, introducing the biomass surrogate (D² × L × ρ) along with degree of decay considerably increased accuracy, yielding a second-ranked model (Adj.R² = 0.75; RMS = 0.24). Although some parameters were not statistically significant (P > 0.05), no collinearity was detected among the models presented (VIF < 5). The goodness-of-fit data indicated that the Loess curve remained linear around the zero line, with changes in residuals aligning with estimation changes around this line. Findings suggested that biomass estimation for Diospyros lotus L. and unidentified species may be unreliable due to standardized residuals falling outside the zero line range, indicating interdependence in error estimation for these species. Conversely, biomass estimates for F. orientalis and Carpinus betulus L. appeared reliable, with variations not being interdependent.Conclusion In summary, biomass distribution and changes in FWD values exhibit significant variations based on middle diameter and length. Due to limited ranges of decay and dry wood density, these additional variables did not substantially enhance accuracy in log-transformed models. Approximately 22% to 25% of variance remains unexplained when estimating FWD biomass using selected optimal models, particularly regarding errors (standardized residuals). This discrepancy is most pronounced for D. lotus and unidentified species. Overall, the models developed in this research for pure beech and mixed beech-hornbeam forests demonstrate broad applicability within the study area. 

 This research aims to review and evaluate the management process of Extra-Hyrcanian Forests in Iran. The first and second parts of this study, published in previous issues of the Iranian Journal of Forest and Poplar Research, examined the management process from its inception until 1996, organized into specific time frames. The current article focuses on the period from 1996 to 2010.

 The sources used to compile this information include reports, implemented forestry plans, identification and semi-detailed studies, field observations, and over 30 years of experience in the Extra-Hyrcanian Forests.

An initial assessment of management actions up to 1996 identified five major reasons for the lack of success in managing the Extra-Hyrcanian Forests: 1) the uneconomical implementation of forestry plans in the short and medium term for forest dwellers; 2) inefficient management based on structural organizations that were prone to evasion of responsibility; 3) divergence, lack of cooperation, and interaction among those involved in managing forest ecosystems; 4) designs based on the model of Hyrcanian forestry plans; and 5) the execution of all activities solely by government entities, resulting in a lack of public participation. Consequently, a forest resource management plan was proposed in 1996 and implemented for two years. The key components of this plan included comprehensive studies, the formation of study and design teams, preparation of a service description tailored to the characteristics of the forests, establishment of community organizations for plan implementation, approval of prepared plans for execution, assignment of implementation tasks to relevant cooperatives, and oversight by the Forests and Range Organization of Iran. Following the presidential elections in 2017, the organization halted the forest resources management plan and initiated three major activities under the titles of Green Movement, Touba Plan, and development of wood farming as its primary initiatives. Since 1998, other plans and programs, including conservation initiatives, have replaced the forest resources management plan, none of which have succeeded.

 In summary, it can be concluded that the period during which forest resource management plans were implemented represents the best management phase for Extra-Hyrcanian Forests in Iran.