مجله جنگل ایران
سال پنجم شماره 3 (پاییز 1392)

Forest roads are the most important factor to access the watershed; nevertheless they are the main sources of sediment production. The delivered sediment by forest roads cause environmental problems and pollution of water resources and are dangerous for aquatic life. Many factors play roles in the amount of sedimentation produced by forest roads with different levels. In this study four factors including road width, road slope, vegetation cover and road age were investigated in sediment production by CULSED model and ArcGIS. Sensitivity analysis was used for identifying the sensitivity of the produced sediment to the mentioned factors and for studying the kind of relativity and its value using Spearman rank correlation test and scenario analysis. Results showed that maximum sensitivity belongs to road width, road gradient, vegetation cover and road age, respectively. The Spearman rank correlation has a direct relativity with road width and its slope, vegetation cover and age have a negative relation with sediment production. These results help the forest roads designers to note the most important factors during the initial stages of the designing process and at the other hand when the road is constructed, they could use the suitable management to control and reduce erosion and sediment yield causing negative effects of roads on the water resource pollution.

This study was conducted to determine the effects of forest conservation on natural regeneration of trees and shrubs and the percentage of Earth's surface covered by tree and litter in Zagros forest. For this purpose, Koshk reservoir forest in Eyvan city and at the vicinity of this region, the Baye forest with similar physiographic characters as control, was selected. 27 0.09 ha sample plots were randomly established in both regions. Number of trees and shrubs regeneration, vegetation, litter and stone cover percentage and litter depth were recorded in each plot. The results showed that forest conservation increased the regeneration of Quercus brantii with seed origin (P = 0.000) and stump sprouts (P = 0.039). It also increased the regeneration of Pistacia atlantica (P = 0.001), and Crataegus pontica (P = 0.014) by stump sprout as well as Cerasus microcarpa (P = 0.003) by seed origin. Koshk protected area had the most tree (P = 0.000) and litter (P = 0.000) cover percentage and litter depth (P = 0.000) than Baye region. The result of correlation analysis showed that natural regenerations of Quercus brantii, Pistacia atlantica have positive correlation with tree (P = 0.030) and litter (P = 0.030) cover percentage as well as litter depth (P = 0.003). Seeds originated from seedlings of Acer monspessulanum have positive correlation with tree cover percentage (P = 0.030), while their stump sprouts have positive correlation with stone percentage (P = 0.020).

Estimates of tree biomass are useful in assessing forest structure and condition, forest productivity, and carbon stocks. On the other hand, investigating the sequestration of carbon in biomass components including wood, leaves, and branches is considered as a useful indicator of site productivity. Although measuring actual tree biomass directly in the field is undoubtedly the most accurate method, it is labor-intensive, time-consuming, and destructive. Therefore application of non-destructive and indirect procedure is important. In this research, randomized branch sampling method was used for estimating above-ground biomass of Quercus brantii Lindl in Chaharmahal and Bakhtiari Province. For this purpose, 30 trees including 16 individuals with single stem and 14 coppice shoots were randomly selected. Quantitative and qualitative traits and tree branches were measured. Then, actual biomass was measured by weighting all tree components and biomass was estimated by randomized branch sampling method. Actual and estimated biomass was compared by paired t–test. The results showed that there is no significant difference between the amount of actual and estimated biomass in different parts of individuals with single stem and coppice shoots. Also, randomized branch sampling method is unbiased procedure in biomass estimation. Although RMSE (%) was high especially in leaf, branch, secondary branch and main branch versus canopy and total. The results showed that randomized branch sampling can be considered as an accurate method for estimating tree biomass.

This study aims at determining the main damage caused by logging in single selection method causing open holes in forests. Little is known about this subject, in spite of extensive studies worldwide. Amount of damages based on the FAO criteria in plots and hectare were assessed according to type, size, intensity and height of damages. Quantitative data of two compartments were compared using t-test. One-way ANOVA and Kruskal-Wallis tests were used to compare multiple groups for quantitative and rating data, respectively. Data were collected by survey of land and one hundred percent measurement in damaged parts. In cutting stage, 79.5% damages were occurred in height >1 m. In skidding stage, 90.4% of damages to wood were observed from a height of 1 meter downward the trunk to the tree root and buttress. The average of the most injuries in the two compartments in cutting and skidding stages were observed in size of 10-50 cm2 (44%) and > 200 cm2, respectively. The intensity of damage in cutting stage is the same (72 percent), but higher in skidding stage, because the slope of cut area in compartment 51 is higher than compartment 121 (95 percent versus 63 percent). The total intensity of damages in compartment 51 was higher than compartment 121 (33 damages versus 19). The rate of injuries to regeneration in compartment 51 in all three stages of vegetation development was higher than compartment 121. The types of damages to stem in compartment 51 were 2 up to nine times, depending on the development stages. The total damages in steep slope were more than gentle slopes (4 times). Ignoring the prescribed cutting direction has a large effect on damage caused.

Eucalyptus occidentalis is an important and fast growing species in wood farming and economic exploitation for leather, paper, essence extraction and pharmaceutical industries. In this study, micropropagation of this species was investigated by planting seedlings in MS and GD medium. Sterilization, stability, shooting and rooting treatments were applied to samples as randomized completely design and factorial trails. 0.1 % mercuric chloride solution for 1 minute was used as sterilization treatment. The results showed that appropriate proliferation and elongated growth branches of E. occidentalis were observed in MS medium containing BAP, GA3 and IBA hormones with 0.5, 0.15 and 0.01 mgl-1 concentrations with 200 mgl 1 P.V.P, respectively. The best rooting treatments was obtained in MS medium containing 1/2 Nitrate with IBA, in 1 mgl-1 concentration. Rooted seedlings were successfully adapted in greenhouse conditions.

The basal area growth equations are directly linked to economic variables such as stand volume. Estimating the stand basal area is essential for economic computation and yield estimation. The main objective of this study is to estimate the basal area growth equations for economic studies. Tree’s diameter at breast height and height were measured in plantations of Populus deltoides Clone No.6955 for two successive years. Due to lack of information on poplar growth at high age, two plantations in Gisoom and Pilambara (with age 26 and 27 years) were also inventoried. Three popular dynamic equations (Korf, Hossfeld and Bertalanffy-Richards) were used for data analysis. Graphical analysis and different statistics (RMSE, R2 and AIC) were used to compare models and select the most appropriate model. Then, the basal area growth equations were validated. For this purpose, 30 percent of collected data were set aside and used to estimate RMSE. The Korf growth equations have been successfully estimated with R² =0.97 and RMSE =1.52 square meter per hectare. The result of validation showed that there is no statistical difference between two set of data in terms of RMSE.

Traditional forest management in northern Zagros is quite old and has been able to meet the needs of local people. Lack of productive and arable lands and consequently, unemployment and poverty have made people to overexploit the nature specially forest lands. Severe intervention of people in traditional forest management creates some conflicts between people and forest management organizations. Development and evaluation of forestry incentive program can be appropriate way for improvement of forest management in these areas. This study was performed in three forest villages, Kochar, Belakeh, Kandesoureh, in Armardeh, Baneh, Kurdestan province. In order to evaluate incentive programs to improve traditional forest management, data obtained from a survey of local communities and qualitative and quantitative methods were used to collect data. In this research 276 households in three villages were studied and 76 questionnaires were completed by household’s holder in the quantitative analysis. Economic analyses of forest and communities relationships showed that livelihood of rural households in the study area is based on two main activities (traditional animal husbandry and agriculture) and furthermore, it shows that animal husbandry has the most dependency on forests. Results showed that people with the profession of animal husbandry have the most conflicts with the government. A systematic approach was used to design incentive programs in the study area to determine driving forces, pressure, state, impacts and response (solutions). Also evaluation of local community benefits from forest, in order to clarify financial value of incentive programs was done. Result of financial evaluation indicated that for preventing pollarding and firewood collection as main reasons of forest degradation, 500 $ per year for each family as incentive programs in 2010 were needed.

Biomass Measurement is one of the prominent procedures for estimating carbon storage and/ or carbon dispersion in atmosphere following global warming. This research aims at modeling the various & different applicable equations in order to increase the accuracy of dry biomass measurement of beech species in natural Hyrcanian forests. This research was backed by natural resources organization so that 21 beech trees could be cut. After cutting and converting the trees, each part of bole which had been converted, was weighed and one disc with 2 cm thickness from the 2-5 m end part of the bole was taken. Then, the samples were taken to lab and they were oven-dried at 105 C to obtain moisture content and constant special gravity. For multiple modeling three variables such as diameter at breast height, bole height and dry wood density were used. The results showed that the combination of height and square of diameter (DBH2 ×H) as explanatory variables would induce the best allometric model. As well, among the whole models presented in this study, the power function just having diameter at breast height (R2adj = 0.922; SEE = 0.241) and log-transformed model having combined variables (DBH2× H) were the best models (R2adj = 0.993; SEE = 0.072) so that they could demonstrate the best goodness of fit. At the end, the ultimate model to estimate the bole biomass of beech in the case study was Y = exp [-3.436 + 0.977 ln (DBH2×h)]. Consequently, this height prediction on the original scale is multiplied by correction factor (CF = 1.002) to correct the underestimation.

Detection and prediction of land use changes are powerful tools in natural resource and ecosystem management. This study aims at monitoring and predicting land use changes using LCM module in the western Marivan region. Landsat images dated 1989, 2000 and 2011 were classified in order to generate digital land use maps. The images were classified into four classes including forest, agriculture, water bodies and built-up area. LCM module in Idrisi GIS software is used to evaluate the land use changes and predict the land uses status in 2011, based on ANN and Markov Chain Analysis. ANN was trained with various spatial variables including distance from roads, distance from residential areas, distance from forest edges, land uses, elevation and aspect. The results indicated that 1234 hectares of the forest area have been reduced during the period of 1989-2011 and the deforestation rate was 0.21 % per year. Moreover the built-up areas have been increased 2.46% (924 ha) in comparison to initial situation. Results indicate very dynamic changes in agricultural areas, as they showed 10 hectares increase and simultaneously 777 hectares decreasing, so in overall 289 hectares have been increased. The comparison of actual and predicted land use change maps, during the period of 1989-2011, indicates that Kappa coefficient for forest, agricultural and built-up areas were 0.37, 0.50, and 0.48, respectively. Based on the obtained results, Predicting Land use changes using LCM was weak in this study area. To study the role of other variables such as soil types, forest types and socio-economic information to improve the performance of the model is recommended.

Occurrence of development stages in the virgin forests including initial, optimal and decay are determined by species composition, which is independent from human activity. In all development stages, some differences such as the amount of light reaching to the forest floor influences soil chemical properties and activity of the soil microorganisms. Soil is a living system in which many biological and biochemical processes occur. In all these processes, enzymes play main roles. This study was carried out to investigate the alteration in activity of dehydrogenase and urease enzymes and some chemical properties of soil in different development stages of Fagus orientalis Lipsky forests in Rezvanshahr area. Soil samples were randomly taken from 0-10 and 10-20 cm depths. Activity of dehydrogenase and urease enzymes, using the substrate and the reaction was measured by spectrophotometer. Chemical properties of soil pH, N, P, K and organic matter were also measured. The results indicated that pH and activities of dehydrogenase and urease have significant differences in different development stages and activity of these enzymes in decay stage is higher than the other stages. This study indicated that decay stage could be a better condition for activity of soil microorganisms. Our findings showed that soil enzymes are suitable indices for presenting differences in developmental stages, and soil chemical characteristics can be effective in the interpretation of results.