مجله جنگل ایران
سال یازدهم شماره 2 (تابستان 1398)

Generally in developing countries such as Iran, the studies in soil mechanics are rarely done or even not conducted due to high cost and time of research and conventional laboratory methods, so the lack of information in this field can damage the construction. Today new approaches such as field spectroscopy are being developed in order to dissolve many of these issues, which is a
non-destructive, fast and inexpensive method. Spectrometry is a non-destructive, fast and inexpensive method that has not been applied in estimation of mechanical properties of forest soils in Iran yet. In this study, we estimated the Atterberg limits of soil (Liquid limit, Plastic limit, Plasticity index, and Shrinkage limit) by field spectroscopy. For this purpose, 45 soil samples were collected from Kheyrood forest (NAMKHANE district) to do Atterberg Limits and VNIR. Partial Least Square Regression (PLSR) was used to predict the Atterberg limits in both the raw spectra and the first derivative of the spectrum. The results showed that PLSR modeling for the parameters of Liquid Limit and Plasticity Limit in the raw and first derivative is very suitable and for Plastic Limit and Shrinkage Limit is weak and not acceptable. Therefore spectroscopy can be used as a fast, inexpensively and accurately acceptable method for predicting the Atterberg limits.

Understanding the underlying mechanisms for tree species regeneration, as well as the positive and negative interaction between tree species and regeneration can improve the effectiveness of forest management and restoration activities. English yew, as one of the rare and valuable native species in Hyrcanian forests, Iran, has declined over the past several decades for many reasons such as lack of regeneration in existing populations. This research aims at studying the spatial pattern of English yew regeneration and its interaction with adult trees. For this purpose, the location of all English yew trees and its regeneration was recorded using TP360 device and distance-azimuth method in the Afratakhteh Forest Reserve, Golestan province. Totally, 417 English yew trees and 59 regenerations were recorded in the research area. The minimum and maximum diameter of the English yew trees was 6 and 124 cm, respectively. The results of the univariate analysis O-ring function showed that the spatial pattern of English yew trees is completely random and spatial pattern of regeneration were clustered in < 5 m, and then it is random. The results of the bivariate O-ring function showed that there is strong competition and negative interaction between the yew tree and its regeneration. It seems the density of the mother trees in the forest and a large shadow over the length of the year by yew trees is linked directly to the absence of regeneration in this forest reserve. Also allelopathic influence of parent yew trees could negatively impact on seedling density beneath a conspecific canopy. The areas out of existing English yew canopies are most likely to represent optimal sites for regeneration. Therefore, in order to protect the existing English yew stands, management activities on regeneration should focus on these areas.

Today, one of the major concerns in the world and Iran is land use change from forests and pastures to agricultural lands which causes soil quality mitigation and global climate change. One of the indicators of soil quality and health is the evaluation of microbial activity and the estimation of microbial biomass of the soil, which in a short time responding to management practices in different ecosystems. This research was conducted to study the effect of climate and forest, pasture and agricultural land uses on soil microbial activities and biomass in Ilam province in 2016. The impact of climate was considered with selection of two regions including Ayvan, with semi-humid climate and Ganjavan, with semi-arid climate. Three land uses including forest, pasture and agricultural land were investigated in each region. After field studies in the land uses, five soil samples were randomly taken from 0-10 and 10-30 cm depths. In laboratory, soil microbial properties including microbial biomass carbon and nitrogen, basal respiration and substrate induced respiration as well as soil organic carbon were measured. The results showed that the highest organic carbon and basal respiration were obtained in the Ayvan climate with forest ecosystem to be 42.54 and 20.72 percent, respectively. Agriculture land use in both climates had the least amount of these properties. Organic carbon, base respiration and substrate induced respiration decreased in different land use with increasing soil depth. The microbial biomass carbon and nitrogen in forest and rangeland land use in Ayvan climate were higher than Ganjun climate. The highest microbial biomass carbon (813 mg g-1 soil) was obtained in forest land use at topsoil (0-10 cm). Soil microbial biomass decreased with increasing soil depth. Soil metabolic coefficient in subsoil (10-30 cm) was higher than topsoil (0-10 cm), and the highest metabolic coefficient of soil (0.179 percent) was observed in subsoil (10-30 cm) with agricultural land use. The lowest metabolic coefficient (0.087 percent) was observed in the soil surface (0-10 cm) with forest land use. In general, the results showed that in dry climate, by changing the land use from forests to pasture and agronomy land in dry climate decreased organic carbon and soil microbial activity. Therefore, correct land management in semi-humid and semi-arid regions can play an important role in improving soil quality and health.

Carbon sequestration through trees is one of the most important strategies to mitigate the carbon emission. The present study was conducted in Khorramabad Agricultural Orchard as randomized complete block design. In each experimental unit, three five-year-old trees were investigated in two groups and 12 poplar colonies or cultivars in three replications. Duncan multiple range test was used to find the mean comparison of the treatments and T test was applied to observe the differences between two groups. The results showed that there is a significant difference in the increment rate and amount of carbon sequestration in the two poplar groups (P<0.01). P. nigra 42.53 revealed the maximum increment in the closed crown group to be 2.6714 m3, and also the highest annual sequestration as 2460.8 kg/ha. In open crown group, the highest increment and carbon sequestration were observed in P.X Pacher to be3.0618 m3 and 1987.909 kg/ha, respectively. Additionally, the open crown group had a higher increment rate compared to the closed crown group. However, there was no significant difference between the two groups in terms of the amount of carbon sequestration. It can be interpreted that the density of open crown group is less than the closed crown one. According to our findings, further studies on carbon sequestration of various tree species and afforestation with fast-growing species with high carbon storage potential is recommended to control the concentration of CO2 in the atmosphere.

Among the different species of Pistacia genus, P. atlantica is more distributed in cold area than P. khinjuk. In this study, in order to illustrate the physiological mechanisms of cold tolerance under acclimation phenomenon, two experiments were established. First experiment was conducted to induction of acclimation on seedlings at two stages and each stage was done for two weeks with different photoperiods. Then chlorophyll and florescence's chlorophyll was measured. For second experiment, leaves and stems of seedlings were exposed to three levels of temperature, +4°C (control), -20°C in one hour and -20°C in two hours. For this purpose, we measure relative water content (RWC) and electrolyte leakage (EL). Results of first experiment showed that 44% electron transport rate and 46% photochemical quenching was significantly reduced. This reduction in P. atlantica was grater by 30% compared to P. khinjuk. Second experiment results revealed that leaf RWC and EL increased during cold acclimation to be 8 and 11%, respectively. In addition, stem EL increased only in P. khinjuk (44%). In fact, P. atlantica due to decreasing of RWC during acclimation was able to maintain the photosystem efficiency and showed more resistance to cold stress. According to our findings, we can identify cold-resistant species or genotypes by measuring the florescence's chlorophyll.

This study was carried out in the oriental beech communities in order to investigate the natural regeneration and assessment of radial growth trend from 1960 to 2016. In each area, 50 1000-m2 circular plots were established based on a random-systematic method. Regeneration was sampled on two concentric circles with an area of 20 and 10 m2 of the sample plot center (for seedling and sapling, respectively). Then, 160 core samples were taken from selective trees by increment. The results of harvested stand indicated that natural and human disturbances regimes lead to change in the diameter distribution, age distribution, radial growth pattern and establishment of tree's regeneration. In the unharvestedarea, sapling of F.orientalis and seedling of Carpinus betulus and Acer velutinum had the highest density. Whereas, the seedlings of F.orientalis and C.betulus were dominate in the harvested stand. During the studied period, 324 tree species were established in the unharvested area and the highest frequency of tree recruitment was belonged to 1970-1980 decades. However, in the harvested stand, 262 tree species were established and the greatest frequency was recoreded from 1960 to 1970 years. The radial growth of trees in the harvested area showed the higher variations during the studied period and the highest frequency of release events was belonged to moderate releases. Therefore, this stand should be managed in order to return their historical composition and structure, maintaining natural regeneration and the optimal development of stand for future.

Due to the interaction of Tree species and its environment, descriptions and analysis of forest types are necessary. The aim of present study was to evaluate modeling distribution of forest types using parametric and nonparametric algorithm. Current research was carried out in Ziarat forestry plan, Golestan province, Iran. 556 samples were taken to measure the quantitative parameters of trees including tree height, diameter at the breast height and type of species via Systematic- Randomize pattern with 150×200 m. After that, the forest types have been determined according to frequency of species. Subsequently, the map of forest types have been produced using Physiographic factors (elevation, slope and aspect), Climate factor (rain fall, evaporating and temperature) via Parametric algorithm (Logistic Regression (LR)), Nonparametric algorithm (Artificial Neural Network (ANN)). The results showed that based LR and ANN, the largest area of forest type was observed in Fageto - Carpinetum with Parrotia persica (23.32%) followed by Fageto –Carpinetum (24.69%). In both methods, the elevation and rainfall events have been recognized as impotent factors. Regarding the limitation of input data and complexity of forest ecosystem, the result of LR and ANN are acceptable. Generally, ANN was more effective compared to LR. However, both algorithms are recommended in distribution mapping of forest type.

The objectives of this study were to evaluate the soil physiochemical properties and regeneration of Prosopis cineraria in Bushehr and Hormozgan provinces, and to determine the most important soil factors effecting P. cineraria distribution and regeneration establishment. For this purpose, we selected four natural pure sites including Chah Mobarak, Nakhl Ghanem, Amani, and Bahdeh in Bushehr and Hormozgan provinces. In each site, five 25*25 m plots were randomly selected and soil samples were taken in each plot in two depths of 0-5 and 6-25 cm. Also, all of the regeneration in each plot, were counted and categorized based on their height (seedlings, <10, 11–25, 26–50, 51–75, 76–100, 101–130, 131–200 and >200 cm height). Collected soil physiochemical data and regeneration classes were subjected to one-way ANOVA. Result indicated that the highest and lowest amount of soil calcium carbonate belonged to the Amani (57.28%) and Bahdeh (80.6 %) sites, respectively. However, no calcium carbonate was observed in Chah Mobarak and Nakhl Ghanem sites. The maximum and minimum soil electrical conductivity belonged to the Chah Mobarak (5.58 ds/m) and Bahdeh (1.28 ds/m) sites at the depth 0-5 cm, respectively. Furthermore, the highest amount of calcium carbonate were recorded in Bahdeh (77.7 %) and Amani (55.4 %) at the depth of 6-20 cm. Soil Organic matter (1.24 %) and nitrogen (0.12 %) were greater in Nakhl Ghanem compared to other sites. Results of regeneration indicated that there are significant differences among the studied sites. Furthermore, Nakhl Ghanem, Amani, Bahdeh, and Chah Mobarak had 3814, 1491, 2813, and 3088 regeneration per ha. No regeneration was recorded in Amani and Bahdeh for >200 cm height class. Based on the results, the most important soil factor effecting P. cineraria distribution are silt followed by sand, potassium and clay. Moreover, nitrogen is an essential soil element in P. cineraria regeneration establishment. However, calcium carbonate and electrical conductivity had negative effects on P. cineraria regeneration and should be considered in plantation plans.

Forest fire and leaf litter is one of the effective factors influencing soil nutrient. Fire intensity and duration can affect the properties of ash and surface soil. The aim of this study was to investigate the physio- chemical properties of ash after the heating of Aleppo oak (Quercus infectoria Oliv.) litter at various temperatures under laboratory conditions. In order to collect litter, Khavmire Abad district in Marivan forest was selected such that litter samples were taken under the crown of the 8 Aleppo oak trees. Trees were selected on a transect parallel to the contour lines, 30 m interval. Leaf litter has milled first and then the samples were prepared in four treatments (milled litter and three treatments heated at 200, 400 and 600 °C). The results showed that the color of ash was dark brown, gray and light gray in temperatures of 200, 400 and 600 °C, respectively. The amount of pH, EC, P, Ca, K and Mg increased significantly with increasing temperature, while OC and TN first increased until 200°C and then decreased significantly. The reduction of nutrient concentrations in the ash of Aleppo oak was: N> C> P> K> Mg> Ca. In sum, temperature can significantly affect the availability of nutrients in ash of Aleppo oak after heating. In addition, different temperatures had significant effects on the amount of nutrients and ash color.

Forestry Cooperatives are the only formal institutions in establishing participatory forestry management in Iran. Forest Restoration and Utilization Cooperatives established for forest management in the Caspian forests during 1980 and 1990 decades. These institutions have faced various issues recently, which lead to failure and dissolution. However, there is not enough analysis in these situations yet. The present study aimed to analyze the problems and obstacles and describe the most important factors on the executive and managerial components of the Narvan, Lil, and Amir-Almomenin Forestry Cooperatives of Restoration and Harvesting, located in the Guilan province. The methodology of the research is Strauss-Corbin based Grounded theory. 28 informants from managing directors, board of directors, Forests, Range and Watershed Organization and Rural Cooperative Organization experts were interviewed based on theoretical sampling. Semi-structured interviews were used to collect the data. The results showed management maladministration, inefficient management, poor training and weaknesses in the knowledge of cooperative managers are the main managerial barriers. In addition, poor implementation, lack of proper infrastructures, equipment and resources, management weaknesses in implementation, and weaknesses in providing training and empowerment of staff are the main drivers of executive obstacles. According to the findings, it can be concluded that the status of cooperatives is beyond the internal issues and members level. As shown in this study, there are many problems in the managerial and executive levels of forestry cooperatives that primarily must be solved in high level decision making among government organizations and then problems in the member level of cooperatives be assessed.