فصلنامه تحقیقات جنگل و صنوبر ایران
سال سی‌ام شماره 2 (پیاپی 88، تابستان 1401)

In temperate regions, the one-year life cycle forms observable growth rings influenced by the genetic, physiological, climatic, and physiographic structures of trees that consider in dendrochronology. Common cypress (Cupressus sempervirens L. var. horizontalis) is a precious Mediterranean species that grows in the Hyrcanian regions, as the only native cypress in Iran. In order to determine the annual diameter growth of this species and to identify the oldest trees, a sample of 92 aging woods was selected in the Hyrcanian habitats of Iran. Samples were collected by an increment borer with a length of 50 cm and measured in the dendrochronology laboratory by Lintab 6 device, and the obtained data were automatically recorded for time matching in TSAP-Win software and time series analysis. After comparative dating and eliminating any measurement error, the mean values of the vegetative ring width of all specimens were calculated and the average growth of the cypress was obtained. The relationship between the width of growth rings in each cypress tree, and the difference in tree growth of the three provinces viz. Gilan, Mazandaran and Golestan was evaluated using R software. The results showed that a tree in Viaeyeh, Rudbar county is the oldest tree in existence reaching an age of 1519 years. The annual diameter growth of cypress is reported as 0.95 mm. The growth rate curve in Mazandaran province during the last 450 years showed milder characteristics in the arrangement, uniformity and slope of change compared to the other two provinces. This indicates the stability of climatic and habitat conditions in Hassanabad, Mazandaran province, compared with the two other areas and sufficient evidence that this area is very close to the Mediterranean climate.

The aim of this study was to investigate the effects of rice husk, rice husk biochar, cow manure and chemical fertilizers on the morphological and physiological characteristics of coliseum maple (Acer cappadocicum Gled.) and ash (Fraxinus excelsior L.) seedlings. A total of 60 pots were considered for nine modifying treatments and nursery soil with three replications in a completely randomized design in Lajim nursery located in Savadkuh county, north of Iran. Results showed that different treatments had significant effects on some morphological characteristics of ash. The highest diameter, height, stem length of this species were observed in 150 g of cow manure treatment and the highest dry leaf weight was observed in 300 g of cow manure treatment. Different treatments had significant effects on the height of first stage, leaf area, volume, cross section and length of roots, leaf dry weight and stem volume of coliseum maple seedlings. The highest height in first stage of this species was observed in the control and the highest root volume was observed in the treatments of 300 and 150 g of cow manure and 2% of rice husk treatments. The highest root cross section, root length, leaf dry weight and stem volume of coliseum maple seedlings were observed in 300 g of cow manure treatment and the highest mean leaf area was observed in 150 g of cow manure treatment. In addition, no significant difference was observed in chlorophyll content and photosynthesis of different treatments. In general, the obtained results show that the use of cow manure compared to chemical fertilizers and biochar has a better function in increasing the growth of Fraxinus excelsior and Acer cappadocicum seedlings during a period of plant growth in the nursery.

The type of litter produced from trees as an influencing factor in ecological processes and the formation of soil horizons plays a key role in the function of the forest ecosystem. In this study, the form of humus was investigated in different forest types on skid trails in different time intervals after skidding operation (6, 10 and 20 years) in Kheyrud forest of Nowshahr County, Iran. Each skid trail was identified with three replications in pure beech (Fagus orientalis Lipsky), beech-hornbeam (Carpinus betulus L.) and mixed beech stands. In total, 81 profiles with dimensions of 30×30 cm2 were drilled in them to be classified using the European Humus Group proposal (EHGP). The mull of the most dominant humus was under the mixed beech litter, while in the pure beech litter the amphi humus was the most abundant system of humus. Three types of humus mull, moder and amphi were observed in the skid trail under beech-hornbeam litter. Oligomull was the most abundant form of humus mull in the skid trail under mixed beech litter, while in the trails under pure beech Eumacroamphi, Eumesoamphi and Hemimoder were the most common forms of humus. The highest thickness of the organic horizons in the 20-year skid trail was under pure beech litter (10.1 cm), while the highest thickness of the organic-mineral horizon was under mixed beech litter (3.8 cm). After 20 years, the humus form in the mixed beech forest stand has become closer to its original form compared to the undisturbed area and has provided better conditions for improving the soil condition.

Investigating community preferences about natural forest parks ecological services and determining their economic value is a useful method for planning and managing them. The purpose of this study is to the economic valuation of Chaldarreh Forest Park ecological services in Tonekabon County, Mazandaran province, Iran. Research data were collected by field survey, and random sampling by completing a Choice Experiment questionnaire by 135 visitors to Chaldarreh Forest Park. In this study, the willingness to pay of individuals for forest ecosystem conservation was estimated by the Choice Experiment method and conditional logit model. Also, a multinomial logit model was used to investigate the effect of socioeconomic variables on the willingness to pay. In this study, willingness to pay each household for the conservation of ecological services in the region, including the attributes of plant species conservation, animal species conservation, water protection and soil protection from the status quo to the improvement situation, respectively, equal to 21560.15, 15880.47, 47440.6 and 21180.85 Iranian rials per month have been estimated. Water protection was the most important ecological attribute of Chaldarreh Forest Park known to the respondents. Also, the final willingness to pay each household for the conservation of ecological services of Chaldarreh Forest Park was estimated to be 106080.07 Rials per month.

Local communities' traditional and dependent livelihood results in many parts of the Zagros ecosystem being slash‐and‐burn agricultural areas. The current study examines the destructive processes of structural components in the slash and burn agriculture in Zagros forests. Quantitative and qualitative factors of all trees were recorded through one-by-one sampling. Quantitative data include species type, a vegetative form (coppice or standard method), diameter at breast height (DBH), tree height, large diameter and small diameter of a crown, tree health, and cut and destroyed roots proportion. Violations reports of natural resources were hired during 2001-2021 to calculate the number and volume of removed trees in three sites. Samplings were taken from the diameter at the breast height in the radial direction via an increment borer to detect differences in 2021 compared to 2001. Therefore, the diameter increase was calculated. The calculating results of the canopy area in 2021 and extracting it in 2001 in the Kasehkaran, Avalviar, and Cheshmeh Phan sites showed that the canopy area has decreased from 54686 to 43180, from 15830 to 12762, and from 22232 to 19064 m2, respectively. The distribution diagram of trees frequency in the diameter classes in studied times showed that the frequency of the number of trees in the three studied areas decreased in the second period compared to the first period. The total volume in 2001 was 153, 1174.5, and 565.6 m3, respectively, which in 2021 decreased to 144, 822, and 515 m3 in the Kasehkaran, respectively the Avalviar, and Cheshmeh Pahn. The removed trees in various ways in these areas include 118, 523, and 132, respectively, over 20 years. Comparing the means results using paired t-test with a probability of 99% showed that the difference between the means of volume factor in the two periods for Avalviar and Cheshmeh Pahn and the tree crown area is significant for the studied three habitats. Although the shifting agriculture extent may seem to have remained the same, its structural degradation has occurred over time. Therefore, these areas should be specifically protected by the appropriate agencies in addition to the regular protection measures.

Commercial volume trees are an important variable that contributes to economic decision-making and analysis in forest management. In this regard, Commercial Volume modeling in Hyrcanian forests is the key to implementing sustainable forest management plans. Due to time and cost constraints and the lack of local or public volumetric measurements in the equations, most forest managers still use traditional expansion factors to estimate volume. Therefore, using independent variables in volumetric modeling is an essential step in fitting models to representation. Therefore, the present study aims to model and predict business volume with minimal error using two ANN and CART algorithms. The study area was parcels 14, 16 and 24 of the educational-research forest of Sari Faculty of Natural Resources located in Darabkola, one of the functions of Sari city. After rotating the forest, masses with different forest types were studied according to the purpose of the study: Trees of pure beech, pure hornbeam and beech-hornbeam. For this purpose, at least 20 trees fell in each type and all standing trees in each sample parcel were measured. In each plot, quantitative characteristics of all trees including total tree height, trunk height (length), diameter per chest and qualitative characteristics including the degree of tree rot were measured. After measuring all the required characteristics of fallen trees at the level of Study forest types by species, to accurately estimate the volume was measured. Then the actual volume of the tree was calculated in the form of different trunk parts based on the ESmalian relationship. Finally, ANN and CART algorithms were used for modeling in STATISTICA12.0 software environment. The results of modeling the commercial volume of three masses of pure beech, pure hornbeam and beech-hornbeam with two ANN and CART algorithms showed the values of R2 explanation coefficient (0.82; 0.77), (0.44; 0.72) respectively and (0.91; 0.84). The results of modeling the commercial volume of three masses of pure beech, pure hornbeam and beech-hornbeam with two algorithms ANN and CART showed that the ANN algorithm with a R2=0.91and the percentage of RMSE%= 10.51 is more precision. Finally, the findings showed that the ANN algorithm leads to better prediction than the CART algorithm. Also, the performance of this algorithm for beech-border mixed mass is higher than any of the pure beech and hornbeam masses.

The number of trees in each diameter at the breast height (DBH) class is considered the diameter distribution model and it is one of the most critical parameters in describing the structure of the stands. The diameter distribution of trees is one of the most important aspects that should be considered by forest managers when deciding on forest management strategies. This study aimed to investigate the diameter distribution functions of poplar (Populus deltoides) trees in the plantation in the Guilan province under the influence of different planting distances. To use models of diameter distribution functions as a tool to obtain reliable information about the structure, growth, and performance of plantations, and to manage silvicultural treatments in these stands. For this purpose, the measurement of all trees’ DBH in the one hectare plots was used in five pure poplar plantations with 5×5 m, 3×5 m, 3×3 m, 3.5×5 m, and 3×4 m planting distance. Kolmogorov-Smirnov fitting test showed a specific distribution function in each stand. The diameter distribution of the trees followed the Beta function in the stand with a planting distance of 5×5 m. The diameter distribution function has of Log-Normal (3P) distribution at a planting distance of 3×5 m. The diameter distribution of trees was a Normal function at a planting distance of 3×3 m, at a planting distance of 3.5×5 m in the fourth stand, the diameter distribution of the trees was fitted as a Weibull function and Normal distribution was shown in 3×4 m planting distance in the last stand. The present study showed that planting distance on the plantation is a factor in changing the diameter distribution functions. At less planting distance, the diameter distribution of trees was normal, and by increasing the planting distance, various diameter distributions were obtained in the stands. Therefore, the present research can be used as a reference study by introducing the diameter distribution model for a mono-culture homogeneous pure stand regarding planting distance. This is practical for stand management to reach a desired distribution or management to transform from a pure stand to a mixed species stand by combining several species with appropriate distribution. In addition, transitioning from a single species structure to a diverse structure using growth performance models is required to simulate this stand's dynamics, the initial step is the determination of the tree’s diameter distribution models as a basic study.