فصلنامه تحقیقات جنگل و صنوبر ایران
سال سی و دوم شماره 1 (پیاپی 95، بهار 1403)

The Hyrcanian forests in northern Iran exhibit diverse rainfall and air temperature patterns. Altitude above sea level is a crucial topographical factor that influences plant growth and development, prompting trees to adopt different morphological, anatomical, and physiological strategies for survival and growth at varying elevations. This study aims to understand the impact of altitude on radial growth and tree-ring width by examining the rate of radial growth of Oriental beech (Fagus orientalis Lipsky) across different age classes in three altitude zones: low, middle, and high altitudes of the Hyrcanian forests in Kordkuy and Asalem habitats.

t three selected sites, located at approximately 700, 1400, and 2000 meters above sea level, tree-ring cores were extracted from 62 beech trees using an increment borer. Following core extraction, the holes on the trees were completely sealed with grafting wax. The surface of each core was prepared using a sequence of 100-, 400-, and 1000-grit sandpaper. Tree-ring widths (TRWs) were measured using LINTAB 5 and TSAP software. Measurements were taken from one side of the core and then from the other side. The obtained TRW series were analyzed using statistical parameters such as sign test, correlation coefficient, and Student's t-test. After cross-dating, average TRW chronologies were prepared for each tree. This method was then used to match the trees within each site. TRW chronologies for each site were verified using statistical methods. A one-way analysis of variance (ANOVA) test was performed to compare TRW chronologies. Meteorological data such as rainfall and temperature were obtained from the nearest weather stations. Meteorological data for Kordkuy and Asalem were obtained from the Gorgan and Astara meteorological stations, respectively.

The findings demonstrated that the elevation gradient had a significant impact on the radial growth of beech trees. TRW in the examined habitats is influenced by elevation above sea level in trees aged 50 to 150 years. The average radial growth of these trees in the middle elevations of Asalem and the lower elevations of Kordkuy is substantially higher than in other altitude areas. The mean growth of trees aged 100-150 years in the middle elevations of Asalem was the highest, amounting to 3.98 mm. Statistical analysis revealed a significant difference between the TRW of trees aged 100-150 years in the highland of Kordkuy with a mean annual growth of 1.94 mm and the lowerland of Kordkuy with a mean annual growth of 2.97 mm. During this age period, no significant difference was observed between trees from the upperland of Kordkuy and the moderate altitudes of Kordkuy, but there was a statistical difference between trees from moderate altitudes and the lowerland. A comparison of trees aged 200-250 years revealed a statistically significant difference between Kordkuy and Asalem moderate altitudes. The mean radial growth of trees aged 300-350 years in the upperland and moderate altitudes of Asalem is 1.25 and 1.32 mm, respectively. Statistical analysis demonstrated that there is no statistically significant difference between the mean radial growth of trees aged 300-350 years in the upper and middle altitudes of Asalem and the lowerlands of Kordkuy.

This study demonstrated that radial growth and tree-ring width of beech trees exhibited notable variations along an east-west transect across the Hyrcanian forests. The observed variations in beech radial growth and tree-ring sensitivity along the elevational gradient highlight the ability of beech trees to develop adaptive functional traits in response to environmental changes.

Different plants from different climates are collected according to the objectives of botanical gardens. Climate is one of the important ecological factors that has the greatest impact on the longevity of plants. Changing the location of the plant from a dry to a humid climate may cause stress and change in vegetative behavior. Therefore, the selection of plants for each region should be based on climate knowledge. The objectives of this research included investigating the effect of climate and nutritional treatments on the growth of wild almond (Prunus scoparia Schneider).

This research was conducted by two related experimental methods. One of which included investigating the effect of climate on the growth of wild almond in Nowshahr Botanical Garden in Nowshahr county in north of Iran and the other one was the nutritional treatments on the seedlings of the wild almond in the Garden. The investigated factors in the climate effect test included the species of wild almond, environmental indicators and soil. The nutritional treatments were carried out as a completely randomized factorial design in three replications in the nursery section that the test factors were three levels of calcium nitrate as foliar spraying with a concentration of zero (control), 5 and 7.5 mM and two levels of potassium sulfate as foliar spraying with a concentration of zero (control) and 6 mM. The time of conducting this research was from 2017 to 2022. The seeds of the wild almond species were collected from the heights of Ghatour valley from Rahal village to Ghatour district located in Khoy county, Iran with an altitude range of 1492 to 1873 meters above sea level. Some parameters related to soil, plant and climate were evaluated at the same time as the experiment started in Nowshahr and Khoy counties. After the seeds germinated and the seedlings emerged from the soil, nutrition treatments were carried out by spraying potassium sulfate and calcium nitrite.

The results of the experiments showed that Nowshahr's climate had a significant effect on the growth indicators of almond species from temperature, humidity, evaporation, sunny hours and ice days. The highest photosynthesis rate of 2.45 mg/fresh weight and the highest plant transpiration rate of 1.35 mmol/square meter per second were observed in Khoy climate. The lowest root length in Nowshahr Botanical Garden was 63.32 cm with the highest share of leafless branches at 60.98%. Correlation relationships of root length in the soil and the intensity of leaf fall (leafless branches) show a significant positive correlation at the 1% level with the amount of plant transpiration. The results of the test data showed that the use of potassium sulfate compared to the control seedlings, led to an increase in the amount of plant growth and, as a result, expanded the canopy width. In this research, the relationship between calcium absorption and transport in the plant showed that the reduction of calcium in the leaf tissues in the control seedlings decreased the resistance of the plant to maintain the leaves. Calcium foliar application increased the amount of calcium in leaf tissue in almonds. One of the effects of this phenomenon is the increase in the durability of almond seedlings to about 30%.

Foliar treatments of potassium and calcium nutrients, although to some extent increased the durability of almond seedlings during the experiment, but the growth disorders caused by the effect of climatic factors prevailed over the nutritional treatment. Therefore, the seedlings could not successfully adapt to the new environment even with the help of nutritional behavior.

Certain structural elements of forests, such as habitat trees, serve as crucial habitats and environmental modifiers for a multitude of organisms. This leads to an enhancement in the structural richness and resilience of ecosystems. The focus on habitat trees and biodiversity conservation in forests entails the management of specific elements inherent in the forest’s natural evolutionary cycle. Consequently, this study aimed to examine the structural characteristics of habitat trees in mixed and transition forests within some managed stands in the Kheyrud forest, Nowshahr County. 

Parcels 305, 306, 309, 310, and 311 in the Gorazbon district were chosen for the study. Gorazbon is a part of the mixed broadleaf forests of the Caspian region, situated within the Kheyrud educational and research Forest of Tehran University. It is located seven kilometers east of Nowshahr city in the Hyrcanian forests of Iran. For this research, all trees exhibiting specific characteristics were measured for their diameter with 100% accuracy across all the mentioned parcels. The conditions sought included broken trees, fungi, hollow from the stump, uprooted, broken stems, deformed, curved, tuberous, with nests, dead trees, old trees, and with witch’s broom. A variety of criteria and methods were employed to identify and recognize each of the qualified trees as a habitat tree, enabling the most favorable evaluation of each. For instance, to identify trees with bird nests, special cameras were utilized alongside human observation. The number per hectare in diameter classes was calculated for all habitat trees in each parcel. Furthermore, the average number and diameter of microhabitat types per hectare were determined across the five study sites.

The findings indicated that the highest frequency per unit area in hollow trees is from the stem and roots, equating to 10.95 trees per hectare, while the lowest is in trees with witches'-brooms, amounting to 0.55 trees per hectare.

The objective of modifying policies in the management of Hyrcanian forests is to emphasize sustainable management practices, enhance forest protection methods, and conserve the forests’ natural values. These endeavors aim to ensure that forest ecosystems persist in providing a diverse array of services to society, such as recreation, water supply, food, wood, clean air, and carbon sequestration. Accordingly, in the study management units, there exist various types of habitat trees, which exhibit diverse quantities and abundances based on the type, developmental stages, and vegetative stage, and are distributed across different diameter classes.

Given the significance of investigating and monitoring riparian ecosystems, this study was conducted to identify and map the land cover, including tree and shrub species classes, around the Zarinehroud River in West Azerbaijan province, Iran. Recognizing that the separation of lands with high spectral similarity using single-time images is not precise, this study utilized a time series of satellite images, capitalizing on the phenological differences of plant species.

The research separated the land cover classes into two stages. In the first stage, the time series data from Sentinel 1 and 2 were used to map different classes of tree cover (natural, wood farming, orchard), shrub cover (natural, orchard), grass or pasture, agriculture, residential lands, soil, and water bodies. Given that seasonal changes in the images can provide valuable information about land cover classes, a one-year (2021) time series of Sentinel 2 optical images and Sentinel 1 radar polarizations for 2021, in the form of median in each season, were processed on the Google Earth Engine platform. The data were classified using four composites of input features and four classifiers. In the second stage, to separate the vegetation classes into Tamarix, willows, orchard, and poplar plantation, the trend of one-year changes of normalized difference vegetation index (NDVI), normalized green red difference index (NGRD), normalized difference red edge index (NDREI), and green normalized difference vegetation index (GNDVI) combined with HV polarization of Sentinel 1 radar in the form of median in seasons, was used as an input feature. The land cover map produced contained Tamarix, willows, orchard, poplar plantation, grass or pasture, agriculture, residential lands, soil, and water bodies.

In the first stage of classification, the input feature of NDVI (Monthly)_ Radar (Seasonal)_ Sentinel 2 (Seasonal) and the random forest classifier were the best feature and the most accurate classification algorithm, separating the classes from each other with an overall accuracy and Kappa coefficient of 88% and 0.85, respectively. In the second stage of classification, the NDVI index between the months of April and November enabled the separation of all four tree and shrub covers. GNDVI between December and April was the best indicator for separating willows. Also, between May to November, it effectively separated Tamarix. NGRDI was suitable between May and November for separating Tamarix and also separated the poplar plantations between April and November. The GNDVI index between April and September effectively separated the two categories of orchards and poplar plantations from Tamarix and willows. The map was generated using the mentioned input feature and random forest algorithm. The overall accuracy and Kappa coefficient obtained from the validation relying on ground samples and Google Earth images were 80% and 0.77, respectively. The main diagonal of the error matrix shows the highest separation between water, soil, and urban land classes. Among the vegetation classes, willows and agricultural lands exhibited the best distinction.

The variation in a plant’s phenology, encompassing leafing, blossoming, fruiting, fall, and sleep cycle, leads to changes in the values of vegetation indicators during the seasons, which can be utilized in mapping vegetation to enhance separability. Consequently, if tree and shrub stands are pure and exhibit a different phenological behavior from their neighbors, they can be distinguished with higher accuracy using time series of satellite images.

Reproduction (regeneration) is a fundamental process that drives the dynamics of a forest, occurring continuously in a healthy and natural forest with a specific spatial and temporal pattern. Natural regeneration poses significant challenges in Zagros forests, Iran. This research was undertaken to examine and analyze the current state of reproduction of tree and shrub species in the monitoring sample plots of Zagros forests. This study, while scrutinizing the species composition, origin, distribution curves, and health of seedlings and saplings, explores the interrelationship between reproduction and nurse species. It will serve as the foundation for long-term studies that determine the temporal changes in reproduction and its characteristics in the Zagros forests.

This research was conducted in the permanent monitoring plots of Zagros, spanning from West Azerbaijan to Fars province. A total of 120 sample plots of 100 square meters were studied within these plots. Each province had 30 studied sites in the typical forests, with 10 of them located in the protected forests. The variables studied included reproduction density by species, origin and type of reproduction, nurse species, height of seedling, terminal bud, and health status of reproduction. A height of 0.5 meters was set as the criterion to distinguish reproduction. The t-test was used to compare parametric data in two groups, while the Kruskal Wallis and Mann-Whitney U tests were employed for non-parametric data.

In the studied area, the reproduction of 20 forest tree and shrub species was recorded, and the density of seedlings and saplings was calculated to be 366 plants per hectare. However, the reproduction was not uniformly distributed, with 37% of the sample plots lacking reproduction. The abundance distribution diagram in the height classes revealed a decrease in the number of oak (Quercus spp.) and hawthorn (Crataegus spp.) reproduction with a height of less than 5 cm. Of the total number of recorded reproduction, 72.5% originated from seeds and 25% were shoots. Overall, 66% of reproduction was dependent on nurses, with oak, hawthorn, stone, and rock playing the greatest roles as nurses. Stones and rocks played a more significant role in the revival of seedlings. Cerasus microcarpa (C.A.Mey.) Boiss., Q. infectoria Oliv., and Q. libani Oliv. had the highest dependence on the nurse, while Pyrus spp., Daphne mucronata Royle, and Crataegus spp. had the least dependence on nurse species. Reproduction sheltered by nurses was significantly healthier than those without nurses. Also, reproduction sheltered by stones and rocks had a higher health rate than reproduction sheltered by trees, although this difference was not significant. Lonicera nummulariifolia Jaub. & Spach, Fraxinus angustifolia Vahl, and Acer monspessulanum L. had the worst condition in terms of reproduction. Despite the presence of mature trees, they had no reproduction (L. nummulariifolia and F. angustifolia) or had very low reproduction (A. monspessulanum). The results showed that the number of reproduction in protected sites was higher than non-protected sites. Although this difference was not significant, the reproduction in the protected sites was significantly healthier.

The results indicated that the reproduction in the Zagros forests is not in a normal situation. However, given suitable spatial and temporal conditions, reproduction occurs and establishes. Although in conditions of disturbance and overgrazing, reproduction attempts to survive by taking shelter near stones, pits, or under thorny shrubs, the conservation of the forest stand by maintaining the tree canopy (oak, hawthorn, and other species) and the forest’s natural structure provides the best conditions for the establishment and survival of reproduction, thereby ensuring the sustainability of the ecosystem.

 Evaluating the management process of Extra-Hyrcanian Forests in Iran is crucial for identifying the strengths and weaknesses of these forests’ management. To achieve this goal, the first part of this article, published in volume 31 of the Iranian Journal of Forest and Poplar Research, outlined the management process of Extra-Hyrcanian Forests in five distinct periods. The first period spans from the initial organization to the establishment of the Forestry Company in 1949, a time characterized by minimal attention. The second period, from the establishment of the Forestry Company to the beginning of the 1960s, marked the inception of attention and the creation of the first organizations. The third period, from 1960 until 1972, saw the commencement of scientific management through the preparation of forestry plans. The fourth period, from 1961 until 1978, witnessed forestry restoration and the development of green space. The fifth period, from 1973 to 1978, focused on the protection and reclamation of forestry plans. The current article examines the management process of these forests from 1979 to 1996.

 The information was compiled from various sources, including reports, implemented forestry plans, identification and semi-detailed studies, field observations, and over 30 years of experience in the Extra-Hyrcanian Forests. After the Islamic revolution until 1996, all types of management methods were tested in the Extra-Hyrcanian Forests without pathology. However, in 1996, a deadline plan was demanded from the organization managing these resources to address the challenge of forest mismanagement in the region. The custodian organization also introduced the general approach of managing Extra-Hyrcanian Forests by presenting a plan. Therefore, although various activities were applied in the management of Extra-Hyrcanian Forests from 1979 to 1996, the details are stated in the following text.

Since 1979, the implementation of protection and reclamation of forestry plans was pursued only in two provinces, Fars and Khuzestan. After a three-year hiatus, from 1983, the Forestry Technical Office resumed the preparation of forestry plans by adding a social and economic component to the studies and reviews of previous plans outside the north (Extra-Hyrcanian). This resulted in the implementation of 15 plans in the Zagros area, six plans in the Irano-Touranian area, one plan in the Gulf and Omani area, and two plans in the Arsbaran area from 1983 to 1995. Regrettably, none of the plans were fully implemented and did not achieve significant success in practice. Regarding the production of saplings and plantation in the aforementioned vegetation areas and during the mentioned time period, statistics have been presented that do not align with the existing reality. Also, in the Gulf and Omani region, 797.75 hectares of man-made forest parks were constructed, and 2069 hectares of unique forest stands were identified and managed as forest reserves. From 1985, the preparation of exploitation model plans for the exploitation of non-wood forest products began. Despite the shortcomings in the model plans, the minimum standards set in the plans were not clearly observed, and the rehabilitation obligations outlined in the written plans were not implemented.

 In summarizing the performance of this period, it can be stated that the relevant offices and authorities continued to follow up on past trials and errors without any coordination and cooperation with each other, operating completely independently.