فصلنامه تحقیقات جنگل و صنوبر ایران
سال بیست و دوم شماره 1 (پیاپی 55، بهار 1393)

Along with the increasing public interest for recreational activities in the natural environment, the total urban green area per capita has been reduced during the recent years, resulted in an aerially-dense concentration of urban forest park users. Therefore, this study aims at conducting a suitability analysis for establishing plantation sites in a 10km buffer around the city of Sanandaj (48145 ha) in Kurdistan, western Iran. Here, a set of relevant factors including the ecology, socio-economy and tourism were studies to identify potential plantation sites. The criteria were spatially mapped following the data analysis. Questionnaires were used for evaluating each geographical map, and the Analytical Hierarchy Process (AHP) method was applied for pair wise comparison of the variables. Convenient weights were consequently assigned to each map based on the relevance of variables for establishing plantations. The final suitability map was derived by overlaying the maps of various factors in the Geographic Information System (GIS). The final map was evaluated and classified into five groups based on the finallyassigned values. The results included the regions with highest priorities which turn out to be more suitable for plantation establishment.

A study was conducted to investigate the effective factors in the formation of the forest structure across the Aras Riparian Zone in northwestern Iran. To this aim, the study area was divided into 5 units based on the vegetation status (natural, artificial), destruction rate of riparian zone and topography. The silvicultural (e.g. density, average diameter, average height, growth form, canopy cover and quality of trees), ecological and socioeconomic ecological, socioeconomic parameters were studied in each unit. The silvicultural parameters were surveyed within a number of 20 sample plots each encompassing 10×1 m which were selected by randomized systematic design. The results showed that species density was the only factor showing a significant difference (p<0.01) amongst the units, whereas the average diameter and the average height did not were not significantly different. As a socioeconomic factor, livestock showed to bear a negative significant correlation with species density (p<0.01), whereas the population proved not to be significantly associated with species density. Further results showed that a difference in soil texture is significantly correlated (p<0.05) with the density of tree species.

Spatial distribution pattern of species plays an important role for understanding forest ecosystem dynamics due to its effect on ecological factors such as establishment, growth, competition, regeneration, mortality, resource allocation, gap dynamic and understory development. In this study, the spatial pattern of twelve tree and shrub species (including Oak, Pistachio, Hawthorn, Juniper, Mahleb, Montpellier Maple, Ash, Almond, Honeysuckle, Cotoneaster, Wild Cherry and Daphne) was explored in Chahartagh forest reserve in Chaharmahal-o-Bakhtiari Province in Iran. Attributes recorded in field included species type and geographic position for individual trees with DBH > 5 cm as well as for shrubs with crown width > 0.5 m within a 52 ha rectangular area. We used Ripley's K function for determination of species-specific spatial distribution pattern as well as the spatial pattern of total woody species across the study. Despite of existing differences in the intensity of aggregation, the results showed that all woody species are distributed in aggregated pattern. The Oak and Montpellier Maple showed the most aggregated distribution amongst the tree species. Furthermore, the trees were shown to follow a aggregated distribution than the shrubs. Compared with other similar studies, the distribution pattern of woody species seems to be aggregated form everywhere across the Zagros region of Iran. The results of this study are concluded to provide useful guidelines for conducting reforestation and afforestation projects for similar test sites. In addition, the study suggests a more cautious choice of sampling strategy for such areas, since the use of common methods such distance sampling can presumably lead to a biased estimation of forest parameters across similar regions.

Hyrcania is a productive region near the southern coast of Caspian Sea. Her forests are mostly uneven-aged beach-dominated hardwood mixtures. There is increasing willingness to treat these forests without clear-felling, following the ideas of continuous cover management. However, lack of growth and yield models have delayed this endeavor, and no instructions for uneven-aged management have been issued so far. 768.4 ha virgin forest of Gorazbon district in Kheyroud educational- experimental Forest was sampled using 258 permanent sample plots in which two inventories was done. This study developed a set of models which enable the simulation of stand development in alternative management schedules and select finally the best method. The models were used to optimize the stand structure and the way in which various initial stands should be converted to the optimal uneven-aged structure. These models firstly developed without site index and age. The model set consists of individual-tree diameter increment model, individual tree height model, survival model, and a model for ingrowth. Logistic model fitted with binary logistic regression analysis was used to model the probability of survival. Non-linear mixed-effects modeling was used in height and diameter increment modeling. The predictors used in survival and increment modeling described the influence of tree size, competition and species. A common model was fitted for all species, using indicator variables to account for any species effects. Competition was described by stand basal area and basal area in larger trees. Competition variables were not included in the tree height model since they would result in instantaneous (and illogical) changes in predicted tree height in simulated thinning treatments. Within the models individual-tree diameter increment model, individual tree height model, survival model had high accuracy, Fagus orientalis and Quercus casaneifolia species had highest incremental diameter between species. In the end, using of growth models have advantages and disadvantages in planning and forest management that aware of this importance can be taken correct and logical decisions.

To improve the nutritional status of Acer negundo trees, a three- year experiment was conducted in the National Botanical Garden of Iran which is currently suffering under low soil nutrient availability and occasional symptoms of yellow leaves. Firstly, samples were taken from both weak and vigorous trees in different stands located inside and outside the project site. Next, a factorial experiment based on a randomized complete block design with four replications was conducted, in which the factor A included the application of organic, inorganic and mixed fertilizers. The factor B included two levels of applying fertilizer via 1) solution in the irrigation water and 2) deep placement. The leaf samples were analyzed at growing season for NPK. Statistical comparison of means based Duncan's test showed an increment of N and K elements in leaves compared to control samples following two-year fertilization. Furthermore, an analysis tree vitality based on leaf chlorophyll availability and leaf nutritional status showed no differences in leaf P concentration between fertilizer treatments as a function of fertilizing method. As a conclusion, optimum levels of N and K content in A. negundo leaves are 1.90 % and 1.20 %, respectively.

Knowledge on physical and mechanical properties of soil is necessary for forest road construction and in turn for optimal forest management. Avoiding a mixture of organic matter with soil is considered as being principal in constructing forest roads which is, however, often neglected. Therefore, quantifying the consequences of such mixture can help optimizing the high economic and environmental costs associated with road constructions. The aim of this study was to assess if and how the level of organic matter affects the physical and mechanical properties of soil on forest roads. To this aim, soil samples were collected by profile excavation. Organic matter was collected from residual and litter layer of forest floor. Different mixtures of organic matter with soil were tested (0%, 5%, 10% and 15% of weight), followed by Atterberg limits and CBR tests conducted on the samples. Results showed that increasing organic matter content would increase plastic and liquid limits, which in turn increases the CBR values. Results also showed a significant negative effect of organic matter on soil engineering properties. Therefore, it necessitates a separation between the organic matter and soil during forest road construction.

Establishing poplar plantations is a practical way for national and regional self-sufficiency in wood production. Therefore, a precise estimation of the growing stock is essential for a consequent economical crop valuation. This study was conducted in a portion of Shafaroud Corporation poplar plantations in the west of Guilan province. Here, 370 individual Populus deltoides trees were selected along a range of 1 cm diameter classes from 7 to 43 cm, which resulted in a within-class sample size of 10 trees. The volume was calculated by Huber and Smalian methods, and the results were statistically compared. The results did not reveal any significant differences between the volumes calculated by the two methods (p< 0.05). The Smalian method entails diameter measurements in the two ends of logs, whereas one measured diameter in the middle of main log is required by the Huber method. Thus, our results support the application of one-factor volume table (tariff) of Huber due to the economical and logistic assets as well as the convenient usage.

Long drought periods during plant growth are result in critical problems in establishment and restoration of plantations in Sahara - Sindian region of Iran. Application of water catchment and storage systems help to reduce drought stress and improve soil physical and chemical properties. To investigate the effect of moisture conservation methods on Moringa peregerina plantations, a 4-year study was designed from 2008 in an area in the vicinity of Rask town at Sarbaz river. The study was conducted using split plots design in three replications with the main plots comprising of seed and pot seedling and the subplots being treated with five moisture conservation methods (straw and dried residual at the bottom of planting dig, tourkinest, plastic film, polymer materials mixed with soil and ditch). The pot seedling treatment resulted in less mortality than the seed treatment. Furthermore, a significant difference was observed amongst the applied moisture conservation methods (P<0.05). The highest survival rate was observed for the plastic film, tourkinest and dried residual treatments, respectively, while the lowest rates were shown by the polymer material treatment. Significant differences were observed between the water catchment and storage systems with respect to Moringa peregerina growth parameters, including total height, stem diameter and canopy cover (P<0.05). The tourkinest and dry residual treatments revealed the greatest performance, whereas polymer and ditch showed the lowest rates. Interaction between treatments revealed the highest growth for tourkinest, dried residual and pot seedling treatments, while the lowest growth was returned when using polymer material with seed treatments. As a conclusion, the application of tourkinest, plastic film and dried residual treatments in combination with pot seedling material are suggested to increase the success in afforestations across the similar arid region.

Forest management and planning require a proper level of quantitative and qualitative information on forest stands. Such data is usually collected by means of different sampling methods e.g. transect method. This study aims at exploring the most appropriate sampling method for estimating basal area incorporating their on precision and cost in a case study of Dalab forests of Ilam province. To this aim, a representative area encompassing 37.2 hectares of forests was selected and surveyed by a 100% inventory. Three sampling methods (transect based on probability theory, transect with fixed 50 m length and transect with fixed number of 5 trees) were applied. Based on a regular random sampling pattern, 37 samples were selected for each sampling method in a 100 × 100m grid. The results showed significant difference between the measured basal area and those estimated by any of the three sampling methods. The E%2×T criteria was additionally applied for a better evaluation of the applied sampling methods. These cost and precision criteria turned out the transect method with fixed number of 5 trees to be the superior to other tested methods, which can be further suggested for estimation of basal area of trees in Dalab Forests of Ilam province.

Climate change and global warming result in an increased amount of greenhouse gases and, therefore, are amongst the most important challenges for sustainable development. The increment in the amount of Carbon sequestrated as plant biomass as well as within the underlying soils is considered as the easiest way to reduce the atmospheric carbon, which can also be economically implemented. In this regard, urban forests play an essential role in the major cities by absorbing the atmospheric carbon. Here, the existing Pinus eldarica stands planted in Bakhtiardasht forest park of Isfahan were studied for their level of carbon sequestration. To perform the estimation, the biomass, soil (in depths of 0-15cm and 15- 30cm) and litter were sampled in a randomly systematic design. The Carbon sequestration in plant biomass and the soil organic carbon were measured by means of allometric equation and Walkly-Black method, respectively. The results indicated that the Pinus eldarica plantation led to an increasing amount of sequestrated Carbon up to 422.4 tons per hectare as compared with the surrounding barren land. The economic value of the resulted Carbon across the entire plantation area was valuated to exceed 5 million USD. The fixed carbon was shown to be mostly stem from the trunk of trees (40 percent). This study concludes such Carbon sequestration to be amongst the essential requirements for existing and upcoming forest conservation plans as an effective step to decrease of atmospheric carbon and mitigate the climate change effects.

The sustainable development of natural resources depends partially on identifying the role of local people’s participation in conservation, restoration and utilization of natural resources. This study aims at investigating of participation level of forest dwellers as well as the effective factors on their participation in forest management. Therefore, a number of 330 forest dweller households and 70 natural resources experts of natural resources headquarters of Mazandaran province in Babolkenar area of Babol Township were sampled for a survey research framework. It led to the selection of 178 households using Morgan table as well as 70 experts from natural resources headquarters via census. The required information was collected by means of questionnaires, which were validated using the executive and professional expertise. The reliability coefficients if 87 and 88 percent were determined by Cronbach’s alpha for forest dwellers and experts, respectively. Furthermore, forest management measures showed that the forest dwellers support conservation and utilization activities generally more than rehabilitation activities. In addition, a positive significant correlation was observed amongst the quality of the implemented management by forest dwellers and a set of factors including their education level, age, agricultural income, interaction with natural resources officers, participation in training courses and the level of awareness on forest benefits. As a conclusion, an improvement of awareness and knowledge of forest dwellers on forest management is suggested.

The optimal computational capability for analyzing multispectral aerial images e.g. for fine-scale tree species mapping is often considerably constrained by their enormous data volume. This may be mainly reflected in a reduction in the speed of data processing as well as in their archiving. This research was conducted to explore the effect of alterations in spatial and radiometric resolutions in the quality of object-based tree species classification by UltraCamD aerial images. The study was conducted in three different study sites. Segmentation was firstly implemented on the original images featuring spatial and radiometric resolution of 7 cm and 8-bit, respectively. The optimum segmentation result was then classified. Following this, rescaling in spatial (to 14, 21, 28, 35 and 42 cm pixel size) and radiometric (16-bit to 8-bit) resolutions were conducted, which was followed by classification of the resulted images using the similar segmentation, input bands, features and training and validation data. Based on the conducted accuracy assessment of the resulted classified images, the accuracy was shown to reduce along with a decrease in the radiometric resolution for all of the three areas. However, the trend was shown to be non-uniform when reducing the spatial resolution of the input data. It is concluded that a downscaling of the pixel size down to 4 times coarser than the original pixel size does not notably affect the classification of even-aged or homogeneous forests, while it should be merely conducted with caution in case of natural stands encompassing undisturbed, heterogeneous and diverse groups of species.

Tree felling could optimally result in a low height of the left-over stump, which might positively cause an increment in the harvested amount of wood and in turn augment the associated income. To study this issue, a number of 254 felled trees were randomly sampled within the Nav compartment of watershed no. 7 in Asalem, Guilan province. Following the measurement of the stump heights, a survey on a set of the most influential factors on stump height (including tree species, slope gradient and stump diameter) was conducted in a randomized block design. Compared to the heuristically-optimal stump height of 15cm, the mean stump height of felled trees was 25.45cm. Results turned out the stump diameter to be an effective variable on stump height, which can lead to a possible loss of 0.02691 cubic meter in harvested volume as well as 47167 Rials of financial income per tree.

The forests located in Kurdistan province, in particular the Marivan forests, are assessed to be substantially vulnerable to wildfire hazard due to the Mediterranean climatic regime within the region. A research was designed here to explore the effects of periodic wildfires on soil nutrient. A total number of 40 soil samples were collected, consisting of 10 samples from 0-20 cm depth within 3 Persian oak (Quercus brantii) stands which were previously affected by fire in 2005, 2008 and 2010, as well as 10 samples from a fire-unaffected natural stand as control treatment. The soil properties were analyzed within the taken samples, which showed the Ca, Mg and EC content to be higher in the burned soils compared to those within the control treatment. Furthermore, the more currently-occurred fire resulted in a higher amount of the three nutrient elements. Concentration of potassium was also shown to be higher in the burned soils, with an exception of the burned soil of 2008 fire.

The expansion of Poplar plantations has been stated to play a decisive role by increasing the amount of wood production, reducing the wood import as well as by creating employment rate in wood and paper industry. Here, a number of 34 native and exotic Poplar clones were explored in a two-year study in a selected nursery of the Chalaki research station in Gorgan. The aim was to examine the effects of stump cutting on the growth in different ages (1/1 and 1/2 age), the results of which will support the decision making process when choosing the suitable clones for Poplar plantations. The sample seedlings were provided by planting 100 cuttings in 20×130 cm spacing grid. The examined clones were selected from 6 species including Populus nigra (12 clones), P. alba (6 clones), P.x.euramericana (9 clones), P. deltoids (5 clones), P. trichocarpa (one clone) and P. caspica 80.4 (one clone). Following the first growth period, all seedlings were cut from the ground level. In the subsequent year, half of the seedlings (i.e. oneyear old stems and two-year old roots) were bred. Then, Collar diameters and heights were measured for all the seedlings, followed by calculating the mortality rate and the rate of growth change. The one-way analysis of variance (ANOVA) and Duncan test were used for comparing the means. The stump cutting was shown to bear a significant positive effect on the growth rate as well as on the uniformity of the seedlings in different clones. The changes in height growth among different poplar groups showed a significant difference (P<0.05). Moreover, the maximum and the minimum changes in height were returned by P. euramericana (70%) and P. nigra (46%), respectively. Native clones of P. caspica 80.4 and P. alba showed maximum percent of height growth changes with their substantial rates of 143% and 109% respectively.

This survey aimed to identify a set of crucial parameters which contribute to form the suitable sites for developing mangroves in Hormozgan Province. Therefore, a systematic literature review on 25 studies in Iran and comparable regions was conducted to identify the potentially-influential factors. It led to the subsequent selection of 3 main criteria and 9 sub-criteria. These were examined across the study site by means of Delphi method. The entire criteria were also weighted by Fuzzy Analytic Hierarchy Process (AHP). The results indicate that the climate, the seawater properties and the physiographic properties (as main criteria) as well as the precipitation, the air temperature, the climate type, the sea waves, the tidewater quality and the physiochemical properties of land (as sub-criteria) play the most vital roles in the formation of optimal sites for Avicennia marina establishment. The physiographic property was the most crucial criterion, whereas the physical properties of land and precipitation were the most and least significant criteria, respectively. The results also returned a compatibility index of less than 0.1 in fuzzy hierarchical cluster analysis, which indicates the compatibility of judgments.