نشریه بوم شناسی جنگل های ایران
پیاپی 14 (پاییز و زمستان 1398)

In this research, modeling tree height distributions of beech in natural forests of Masal that is located in Guilan province; was investigated. Inventory was carried out using systematic random sampling with network dimensions of 150×200 m and area sample plot of 0.1 ha. DBH and heights of 630 beech trees in 30 sample plots were measured. Beta, Gamma, Normal, Log-normal and Weibull probability distribution function were surveyed. Characteristics of distribution functions were estimated by using of maximum likelihood method. Actual probability and probability which derived from functions was compared using Kolmogorov-Smirnov and Anderson-Darling tests. Results of Kolmogorov-Smirnov test showed that only Beta probability distribution function was suitable for modeling height distribution of beech; while results of Anderson-Darling tests demonstrated probability distribution functions of Beta, Normal, and Weibull were fitted to the height distribution of trees. Therefore probability distribution function of Beta was selected for modeling height distribution of beech.

In this study we evaluate the effects of different types on soil Physical and chemical Properties and plant species biodiversity in the hyrcanian forests of Iran. For this porpuse 33 sample plots were established in 5 vegetation types consist of pure beech (Fagus orientalis), Ash plantation (fraxinus excelsior), spruce plantation (Picea abies), mixed forest and degraded forest. In each vegetation type, a square-shaped surface area of 4 hectares (200 × 200 m2) was separated and the sample plots with an area of 400 m2 (20×20 m) to evaluate the herbaceous community and regeneration of woody vegetation were implemented by systematic random sampling method. A soil sample was taken from a depth of 10-0 cm to assess physical and chemical characteristics of the soil in each plot. The results showed that there was a significant difference between the understory diversity indices in 5 vegetation types based on Simpson and Shannon Wiener diversity indices, and the mixed  and degraded forest have the highest values. Also, the results of the comparison of vegetation biodiversity indices in the regeneration part showed that Margalef, Menhinick, Simpson and Shannon Weiner indices had significant difference among the vegetation types and the mixed forest had the highest values. The results of analysis of variance of soil characteristics showed that only soil moisture content, acidity and carbon percentage had significantly different among the vegetation types. Totally, the results of this study clearly showed that the mixed forest had the best performance in terms of plant biodiversity indices and physical and chemical of soil characteristics than other vegetation types.

Forest soil compaction influenced by the use of skidders machineries, its power and weight, then causes changes on specific physical characteristics of soil. In most of the investigations, the negative effects of skidder traffic is reduction in growth of trees. The aim of this research was investigating the effects of number of skidder traffic in different skidding direction (uphill and downhill skidding) on soil compaction and forest seedlings establishment, through using rubber–tired skidder, the Timber jack 450c in compartments 9 and 11 series of the Dehmian exploitation corporation Choob-e-Farim company. The number of traffic at five levels (0, 1-5, 6-10, 11-15 and >15 passes) and two levels of skidding directions (uphill and downhill) were measured. After logging operations, sample plots with 9m2 size were recorded within the skidding trails. Bulk density, seedling density and root volume were measured on the disturbed surface and within the skidding trails. Results showed that the most bulk density increase was occurred during the first few passes of skidder (1-5 traffic). The increases in bulk density were considerable at the sampling depth of 20-30 cm. Uphill skidding soil compaction were higher (1/24 gr/cm3) than downhill skidding (1/19 gr/cm3). Uphill and downhill skidding directions did not affect the seedlings density. Traffics by more than 10 times at uphill and downhill skidding reduced the seedlings density and growth. The number of allowed traffics in uphill and downhill determined 7-8 and 11-12 times respectively.

Yellow mistletoe is a semi-parasite plant lives in the Zagros forests on Persian oak trees. Mechanical control is one of the basic acts to manage yellow mistletoe contamination. This research aimed to evaluate the performance of mechanical methods; wood-glue, clay, black plastic, natural color and control treatment to control yellow mistletoe at different altitudes and selecting the most suitable methods was carried out in Hyanan oak forests in the northern part of Ilam province. Three research sites were selected at altitudes of 1600-1800, 1800-2000 and 2000-2200 m a. s. l. At each site, three Persian oak trees for each treatment and in total 15 trees were selected. Implementation and monitoring of treatments was done during five years (2010-2014). Results showed that the effect of control treatments on the removal rate of yellow mistletoe on the treated branches was significant. Also, the effect of altitude on the frequency of new yellow mistletoe tubers on other branches of treated trees was significant. Results showed that wood-glue and clay were 100% successful in removing yellow mistletoe. But the control performance of black Plastic and natural color was 30% and 0%, respectively. It was concluded that cutting of yellow mistletoe infected branches and coating their cutting locations with clay or wood-glue cause eliminate the yellow mistletoe and prevent its re-establishment on the limb. The combined control methods of wood-glue and clay are advisable to run for fighting against yellow mistletoe.

Changes in the quality of water reaching forest floor are of the most important consequences of native and exotic tree species plantations for rehabilitating the derelict areas of the Caspian forests. The aim of this study was to compare the chemical composition of throughfall in plantations of Persian maple (Acer velutinim Bioss) and Turkish Pine (Pinus brutia Ten) in Darabkola Forest, Sari. The amount of gross rainfall and throughfall were measured using six and twenty plastic collectors, respectively, from May 15, 2012 to 15 March, 2013. To compare the concentration of Potassium, Calcium, and Magnesium of the throughfall, four throughfall and rainfall samples were monthly taken from each stand. The results showed that the average of EC in growing season in Persian maple stand (170 µs/cm) was significantly higher than in Turkish pine stand (135 µs/cm) and in rainfall (55 µs/cm). Mean concentration of Potassium (Acer: 6.15, Pine 5.63 mg.l-1), Calcium (Acer: 0.53, Pine: 0.83 mg.l-1) and Magnesium (Acer: 0.59, Pine: 0.55 mg.l-1) were not significantly different between Acer and Pine stands. Mean concentration of potassium and magnesium in Persian maple stand (K: 6.15, Mg: 0.59 mg.l-1) and Turkish pine (K: 5.63, Mg: 0.55 mg.l-1) was significantly higher than the rainfall (K: 0.24, Mg: 0.32 mg.l-1). We concluded that the plantations change the water quality reaching the forest floor. It is needed to examine the effects of all endemic and exotic tree species on chemical composition of throughfall in future studies.

One of the important goals of natural resource management is to conserve plant diversity in the ecosystem so that sites are more productive and more ecologically stable at the various situations. Different diversity indices have been presented to study the species status of natural ecosystems. One of these indicators is the use of empirical distribution models that each of these models indicates the sustainability and health of plant communities. This research was carried out in Guyje bel woodlands of Gechigiran region in order to know about the extent of degradation and stability of plant communities in two levels of altitude. For this purpose, 50 samples were taken in two altitude levels; lower and upper than 1800 m above sea level. We recorded the percentage of shrubs and trees species in the plots. Parametric indicators including diversity grading curves and frequency distribution models (broken wands, logical norm, logarithmic series and geometric series) were used for graphical study of plant diversity and their fitting with experimental models of sustainability of plant communities. The results showed that, by examining the fitting of species abundance data, using the Chi-square fit test, the plant community of both altitude classes follows the logarithmic series model at the 5% level. Since the logarithmic series model represents unstable communities and the plant community has a relatively small number of species, it can be expected that these two sites were in a low diversity in terms of species diversity and stability. Both elevations had a significant fitting of 5% with the geometric series model. According to the results, the lower altitude (lower than 1800 m) had a lower diversity than the higher altitudes (above 1800 m). Therefore, it is suggested that management decisions should be made to increase species diversity in the mentioned areas.

In this research, the capability of Rapid Eye satellite imagery for mapping the crown distribution of oak trees in Zagros forests was investigated in the Dashtebarm forest area of ​​Kazeroun, Fars province. In this study, data quality was investigated geometrically and radiometrically and geometric correction of the images was done using a linear method and using precision ground control points. In order to investigate the use of artificial bands obtained from appropriate processes in the classification process, images of appropriate plant spectrum indices were created by mapping the bands and images of the main components using the principal components analysis (PCA index). The vegetation map of crowns of trees was measured by measuring the crowns of trees in square sample samples with an area of ​​400 square meters in a randomized way. 70% of samples were selected as educational sample and 30% of the rest were randomly selected. Two-point and polygonal classification with two maximum likelihood algorithms and support vector machines was performed on the original image, the processed bands, and the main image composition of the processed bands. The results of the accuracy assessment of the maps in this study showed that the highest overall accuracy and Kappa coefficient were 98.52% and 0.97, respectively, in the point of processing with processed bands and maximum likelihood algorithms, as well as with the image composition The original is with processed bands and support vector machines algorithm (SVM). Also, in the polygonal classification, the highest overall accuracy and kappa coefficient of the maps classified using the processed bands were 87.50% and 0.75 with the maximum likelihood algorithm and 90.78% and coefficient Kappa 0.81 has been supported by the car engine algorithm. In general, the results of this study showed that Rapid Eye images are suitable for preparing the crown distribution map of forest trees in Zagros forests.

Knowledge of the decay trend of dead trees and site factors affecting their functions, plays an important role in the development of conservation management plans in forestry projects. This research was conducted in Asalem beech forests in northern Iran to assess the impact of physiographic features of the site on the process of dead trees decay. A total of 90 sample cuts of dead beech stumps were randomly selected and studied. For each sample, species, diameter and decay classes were recorded. The effect of aspect Slope Index (ASI), Terrain Shape Index (TSI) and Landform Index (LI) on the physical properties of dead wood (density, weight, moisture content) and biochemical components of wood (lignin, cellulose and hemicellulose) on the process of decay were investigated. The mean decay rate of dead beech stumps calculated 0.061 and the mean of beech was 0.32 that varied between 0.05 and 0.62 grams per cubic meters. The results revealed decay process requires about 46 years and the four classes decay showed significant difference in terms of wood density, lignin and cellulose. Meanwhile, the LI was the most important physiographic factors influencing the decay rate of dead trees. The lignin content of the deadwoods was significantly influenced by the form of land. Accordingly, it can be concluded that maintenance certain volume of dead tree in the forest stand structure need to taking account into the dynamics of dead trees, as well as the effects of geomorphological characteristics of site, especially land form conditions

In order to evaluate the growth function of Populus nigra trees under homogeneous conditions, a total of 24 individuals of P. nigra (3 individuals per stand) were sampled from 8 artificial stands in Kermanshah province and 12 individuals of P. nigra (3 individuals per stand) were sampled from 4 artificial stands in Zanjan province. In order to assimilate environmental conditions, seedlings were planted under randomized complete blocks design with 3 replications in Karadj area. In growing season, height growths were measured in 6 periods and diameter growths were measured in 2 periods. The results showed no significant differences between stands in term of height and diameter growths but there were significant differences between periods in terms of height and diameter growths. In total, the results of growth parameters measuring in P. nigra stands showed the trees of the two provinces presented a fairly similar growth function during a growing season.

Forest utilization is one of the important components of get income and decrease of poverty for local communities. Zagros as the widest forests area in country, in terms of commercial non-wood forest products are unique. The amount of income from these forest products varies, and in each region a specific type of product is the important source of income. The purpose of this study was to determine the percentage of forest income in annual household’s income and determine which forest products constitute the annual net income of a household and what kind of product is the most source of income in each region are from. For this purpose, various utilizations and the share of forest products in the lives of the northern Zagros households (Marivan, Baneh and Saravabad cities in Kurdistan province and Piranshahr and Sardasht in West Azarbaijan province) were investigated. The gathering of Gazu, Mazooj, oak seed, Gala (grazing), galipot of Pistacia sp., firewood and food-medicine plants were among the most commonly used forest products in the region. The data of this study included income and cost of different sources by direct observation, semi-structured questionnaire and interviews with 220 households of the utilizer. Livelihoods sources of utilizers were analyzed in three groups of forest products, husbandry and others. The results showed that the livelihoods of the utilizers of the region, forest products, husbandry and others, respectively, were 15.12%, 22.75% and 62.13%. The annual profit from forest products in Marivan and Sarvabad was more than the annual profit from livestock, while in Piranshahr, forest resources did not have significant profits. Also, the highest net annual income of the forest in the cities of Marivan, Sarvaabad, Baneh, Sardasht and Piranshahr was respectively galipot, galipot, Gala (grazing), galipot and forest food products. Considering that each of the cities is better in producing one or two products. It was suggested that planning for the sustainability of resources (including determining the possibility of harvesting), improving the mechanisms of utilization, processing and marketing of the important products of each city was proposed.

Climate changes due to changes in a habitat leads to differences in the rate of decomposition and nutrient dynamics of leaflitters, which has many effects on the controlling factors of the decomposition process. In the present study, the rate of decomposition and nutrient dynamics of Norway spruce was evaluated for 363 days in the two forestation sites in the natural and foreign habitats, Stråsan and Lajim. Nutrients such as nitrogen, phosphorus, potassium, calcium, magnesium, manganese and lignin, as well as Limit value, constant coefficient of decomposition and production capacity of humus were investigated using standard methods in both habitats. Nutrient and lignin concentrations were measured individually in each country using the same measurement methods. The results showed that the initial quality of needles, except for calcium and manganese, in Lajim habitat (the concentrations of nutrients in nitrogen, phosphorus, potassium and magnesium were 12.63, 1.23, 9.85, and 1.51 mg/g) was better than Stråsan (the concentrations of calcium and manganese were 13.4 and 1.38 mg/g). The dynamics pattern of nutrients in two habitats was similar during the study period, but in 363 day, there were significant differences (p <0.05) in the concentrations of manganese and phosphorus. The remaining weight in two habitats at the end of the period did not show any significant difference (Lajim and Stråsan habitats were 77.69% and 77.92% respectively). The constant coefficient of decomposition and production capacity of humus in Lajim habitat was higher (respectively, 0.24% per day and 66 fractions) than Stråsan habitat (respectively, 0.1% per day and 55 fractions). Based on the stepwise regression, in the Lajim habitat the concentrations of phosphorus and manganese and in the Stråsan the concentrations of lignin, magnesium and calcium were the only variables which explained mass loss var iation. In general, the results of this study showed that Norway spruce in Lajim habitat was successful in the view point of the decomposition and nutrient dynamism and in the compared to its natural habitat, and could be used in the Hyrcanian mountain forest for reforestation projects.

Tree marking can cause changes in forest. This study aimed to assess tree marking operation and to predict its effect on stand structure of Persian ironwood-hornbeam stands at Bahramnia forestry plan, north of Iran. Therefore 98 trees that were marked in compartment 9 of the mentioned forest in 2017 based on selection system and according to the recent laws of Forests, Range and Watershed Management Organization of Iran were measured before cut. Characteristics such as tree species, diameter, height, volume, decay condition and standing or fallen situation of the trees were recorded.  Independent samples t-test was used to compare the mean diameter, height and volume between marked trees and stand trees. To obtain the mean diameter and height of the stand trees 16 circular sample plots with the area of 1000 square meters were considered in which the diameter and height of all trees were recorded. The results showed that the majority of marked trees, based on both tree numbers and volume, belong to hornbeam species while the dominant tree species of the compartment is Persian ironwood tree. This result shows that the marking operation acted to change the species composition of the stand in favor of Persian ironwood species. In comparison of the mean diameter, height and volume between marked trees with stand trees a significant difference were observed in terms of diameter and volume, but in case of trees height no significant difference was found. Studying the distribution pattern of marked trees indicated a cluster distribution pattern. Totally it can be concluded that tree marking operation according to the recent laws of Forests, Range and Watershed Management Organization, which emphasize on marking and cutting of fallen and broken and decaying trees, in long term will result in loss of dead and decaying trees in forest ecosystem and will decrease ecological capacity of these forest ecosystems.