مجله جنگل ایران
سال دوازدهم شماره 1 (بهار 1399)

Zarde-Kija mushroom(Cantharellus alborufescens) is one of the edible mushrooms belong to the Cantharellaceae family. It is widely distributed in the northern forests of Iran and is desirable for local residents in these areas. Despite the economic importance of this genus, litthe is known about their habitat requirements. This study was conducted to identify the environmental factors affecting the distribution of this mushroom in a plain forest of Noor city (Mazandaran province, northern Iran) with 120 ha area. For this purpose, 20 pair plots (20 m × 20 m) with at least 100 m distance were established (20 plots with Cantharellus and 20 non-Cantarellus plots). To analyze the species-environment relationship (soil characteristics), three groups of plant species were identified by the TWINSPAN method. The results showed this mushroom presents in oak-hornbeam stands with following conditions: clay-loam soils, pH value 5.7-7.2, soil C content 2.2-3.7%, total N 0.16-0.27%, C:N ratio 10.8-18.9, water content 29.4-46.2% and litter thickness 4.8-19 mm. In this regard, soil C content, C/N ratio, amount of sand and clay in plots with Cantharellus was 36, 71, 30 and 18 percent greater than those in plots without Cantharellus. Also, Nitrogen concentration (N), ammonium (NH4+), nitrate (NO3–), litter thickness and amount of silt in non-Cantarellus plots were respectively 30, 20, 19, 48 and 28 percent lesser than those in plots containing Cantharellus. Overall, our findings showed that C content, C:N ratio, sand (%) and clay (%) were the most important factors influencing the presence of C. alborufescens.

Social evaluation of natural resource projects in rural areas of Iran, which has certainly numerous positive and negative impacts, can have an important role in identifying the strengths and weaknesses and improving the implementation process of such projects in the future. The purpose of this research is the social evaluation of the Hosseinabad carbon sequestration project in South Khorasan using the network analysis method to investigate the level of trust formed between the people and the organizations involved in the implementation of this project. According to the results of this study, the evaluation of different trust network indicators showed the formation of a coherent and integrated network among the beneficiaries of the project. The formation of trust indicates the positive impact of the project executives on the local people's perspective and promises to provide a suitable environment for the implementation of natural resource projects in this area. A study of the power distribution among organizations also shows that out of the 44 organizations studied, most of the power is owned by about 10 organizations, which is one of the weaknesses of this project and it is suggested to distribute the relationships based on uniformity. Confidence in the entire network with proper planning and policy reduced the focus of power in one or more limited organizations.

The patterns of nitrogen distribution in the world are changing and today have become a serious environmental problem. The aim of this study was to investigate the biochemical response of soil and litter to simulated nitrogen deposition in chestnut-leaved oak (Quercus castaneifolia). Four treatments in twelve plots of 20 m × 10 m2 were randomly established in the plantation stand. Four simulated nitrogen deposition treatments were considered including zero (control), 50 (low), 100 (medium) and 150 (high) kg N ha−1 year−1, with four seasons in each month. At the end of the simulated period, an increasing trend in nitrogen, phosphorus and potassium was observed in high nitrogen deposition treatment. The carbon in the litter layer at the end of the simulated period was also significant (P < 0.01) at levels of 100 and 150 kg N. At the end of simulation period, the lowest soil pH changed were observed in the high treatment and the highest in the control treatment. The highest amount of potassium and phosphorus were observed in control treatment 290±5 and 15±0.1, respectively, while in the high simulated nitrogen treatments the lowest values were 221±4 and 8.1±0.1, respectively. The results of this study showed that when the nitrogen content in the soil increased, it could decrease the rate of decomposition and microbial activity in the soil and cause a change in the chemical composition of the litter layer.

The present study reveals for the first time the rate of soil erosion using radioisotope method in the Hyrcanian forests, which were harvested three decades ago by strip harvesting. Based on the available records, the selected area in compartment 703 of Chafroud Guilan region was selected. In order to study the soil stability in field operations, a scraper plate was used to take samples in different depths of the reference area, from 2 centimeters depth up to 30 cm (maximum penetration depth of cesium). Then, in the reference, harvested and non-harvested areas, some samples were taken by core sampler. Samples were prepared according to IAEA guidelines and then, the quantity of their radiocesium was counted in the laboratory of Atomic Energy Organization. Finally, the mean 137Cs zones of the selected samples were 5894.1 Bq/m2. Therefore, in order to achieve the desired objectives of the study, three models named as MBI, MBII, and Proportional Conversion were used to reveal the erosion rate in which it was discovered that the non-harvested natural strips had some rates of 0.2, 0.7 and 0.6 t-ha-1-y-1, while in the harvested strips the rates were increased up to 8.87, 5.80 and 4.77 t-ha-1-y-1, respectively. Accordingly, it resulted in an average soil loss of 1.2 mm in the harvested strips and 0.9 mm in the natural parts per year and after 29 years of harvesting. Consequently, they can be considered as efficient methods in studying the forest hydrology and they also showed the protective role of forests in reducing the soil erosion.

In most ecosystems, the disturbance is an important agent of variation in community structure and composition. Determining the diversity and composition of the soil seed bank is essential for designing the conservation and restoration programs. In this study, the characteristics of soil seed banks were examined in different periods after a fire (One-year, five-year, ten-year of fire and control) in Kuhdasht city. In each area, 40 samples were collected from 0 to 20 cm depth. A 20 × 20 cm metal frame was used to collect soil seed bank samples. After the chilling treatment, soil samples were transferred and spread in the greenhouse. The results showed significant differences between similarity indices in the soil seed bank in four regions. The highest similarity of the soil seed bank and above-ground vegetation was observed in the control area and then 10-year in the fire area. The result of DCA showed that different fire severities and their effects on site conditions have been reflected clearly in the composition of the soil seed bank. Also, results showed the soil seed bank density differed significantly between four regions. The species with the highest soil seed bank density in the 10-year, 5-year, and one-year area were more and hemicryptophyte. The Shannon diversity, Margalef richness, and evenness indices differed significantly among the four regions. According to the results, changes in habitat after the fire in the short term are evident in soil seed bank composition and these changes are recovered over time.

Part of the forest protection mission is carried out by a special unit in the Natural Resources Offices, which is currently operating under the supervision of the IRI's police. The present study was conducted using the descriptive-survey method. The study population consisted of 220 forest guard officers in Golestan province, which 132 of them were studied by stratified random sampling method. The data gathering tool was a questionnaire. The validity of the questionnaire was confirmed by face validity and referring to university professors and experts from the Natural Resources Department and officers of the Protection Unit of Golestan province. Collected data were analyzed by SPSS16 software through factor analysis. The results showed that the occupational stress of the forest guard officers is more than a moderate level. The occupational stress of the forest guard officers comes from 11 factors, among which "organizational challenges," "work hazards" and "laws and relationships," with an explained variance of 15.96, 6.38 and 6.17 respectively, have the most critical role occupational stress. Given the relatively high level of job stress of forest conservation officers, serious action needs to be taken to reduce it. Ensuring the suitability of individual characteristics with forest conservation jobs, upgrading conservation officers' knowledge of laws and procedures to resolve conflicts with local communities, paying adequate and timely salaries, providing the necessary equipment, reduce the extent of the area under the protection and training of individual strategies for coping with stress is the suggestions of the present study to reduce job stress.

Natural forests provide a wide range of ecosystem services especially water-related benefits. However, the effects of afforestation in different situations may lead to contradictory results. In some cases, afforestation considered as a land use activity that threatens water resources security. So, it is necessary to evaluate the afforestation development in fragile ecosystems, such as arid and semi-arid regions. The main goal of this study is to quantify the hydrological responses of Latian Dam watershed to afforestation projects. To reach the goal, SWAT model were employed combined with meteorological data (daily), hydrological data (monthly) and spatial data to simulate the out flow of Latian Dam watershed, located in northeast of Tehran-Iran, under two land use scenarios (baseline & afforestation). The SWAT model showed good performance in the Latian Dam watershed with acceptable values for Nash-Sutcliffe, P-factor and R-factor which were 0.82, 0.82, 0.68, 0.98 respectively for calibration and 0.83, 0.84, 0.78, 0.78 respectively for validation at the outlet of watershed. Simulation results under proposed scenarios demonstrated that as afforestation expansion 8.5% of the study area, runoff declined by 2.7% in downstream. This research quantitatively showed that afforestation will reduce the runoff in Latian watershed. The result of this study suggested that it is necessary to fully assess the effects of afforestation development in the given area, especially on hydrologic responses of watershed.

The aim this study was to investigate effects of Prosopis cineraria (L.) Druce and Prosopis juliflora (Sw.) DC on physiochemical characteristics of soil and compare them with open area in mixed stand of south forest of Iran. For this purpose, we selected 15 p. cineraria and p. juliflora in the mixed forest of Sirik, Hormoazgan province. Then combinative soil samples were randomly collected in four geographical directions (10cm depth) under each tree and open area in spring, 2018 and were transferred to the laboratory in order to be measured pH, soil moisture, organic matter, electric conductivity, calcium, sodium, potassium and magnesium. Result sowed that all soil characteristics (except for pH) are higher under tree than those in open area (p<0.05). Also magnesium, organic matter and moisture with the amounts of 72.23 mg/L, 1.32% and 15.00% were highest under p. cineraria crown. Amounts of potassium, sodium and magnesium (239.7, 174.93 and 206.75mg/L) were highest under p.juliflora crown. In addition, EC (2.32 ds/m) increased and pH (7.10) decreased than those in open area significantly. In according to this study, p. cineraria and p. juliflora influence on soil ochemical characteristics (except for pH and EC) positively but totally due to remarkable effect of p. cineraria on key characteristics of soil moisture and organic matter and negative effects of p. juliflora on electrical conductivity increase in sensitive ecosystem of south of Iran, afforestation by native species is preferred than to exotic species.

For designing forest roads that in addition to minimize the cost of constructing, satisfy environmentalists, it is necessary to provide designers and contractors accurate data from surface and subsurface conditions of the road area due to the large-scale of data using of optimization methods (metaheuristic algorithms) with the help of computers is necessary. For this purpose, this research was carried out on a proposed forest road whit length of 1 km in the forests of the district 4 of Babakoh in the city of Siahkal in Guilan province. The cycle of all earthwork work was studied by continuous time study method and the information of the subsurface layers terms of digging was carefully recorded. The results of comparing the method of the ant colony with the hand-made design scenario showed that the multi-objective algorithm presented in this study has great potential for reducing the cost of earthwork operations and its volume. Based on the results, the algorithm is able to reduce 58.55 and 64 percent the cost of earthwork operations and the volume of operations, respectively. Finally, the results of this research can be used as a guide to better management of forest areas, especially forest roads with the development of efficient methods in all forestry forests.

Orthphoto mosaic, and digital elevation models (DEMs) that created from UAV imagery can be used to delineate tree crowns. The goal of this research is to compare two segmentation techniques in the estimation of crown diameter. In this regard, two successful flights were carried out in two different seasons (leaf-off and leaf-on). Then we generated accurate CHM through a photogrammetric workflow using DTM and DSM. We used invert watershed (IWS) and multiresolution segmentation (MRS) to detect tree crowns on CHM and orthophoto mosaic, respectively. To compare the estimates of mean crown diameter from UAV images with actual values, 95 trees were measured. The results of comparing the estimated and field measured values showed that all two algorithms effectively delineate tree crowns. The results of linear regression showed there is a high agreement between estimated and measured values, which were (R2=0.88) for MRS and (R2=0.92) for IWS. The best result was obtained using IWS techniques (RMSE= 7.02 % and MAE = 5.97 %). T-test results showed that there are no significant differences between the field measurement and IWS estimated values. Although the t-test result showed there are significant differences between the means of MRS estimated and measured crown diameters, but based on RMSE (8.74 %) and MAE (8.11 %) of the MRS technique, the error of crown diameter estimation was small and therefore acceptable. Finally, the results showed that this methodology, as an accurate and low-cost process, could be used to estimate mean tree crown diameter.