فصلنامه تحقیقات جنگل و صنوبر ایران
سال بیست و یکم شماره 4 (پیاپی 54، زمستان 1392)

This study was performed in order to investigate microhabitats in compartments 317 (managed) and 318 (control) at Jamand district of Golband forest, located in Noshahr (Mazandaran province). Random systematic sampling method was selected with regular gird of 100 × 200 m and 1000 m² area sampling plots. Type and number of defined microhabitats were recorded in each sampling compartment. Species of host trees at each microhabitat were determined and its diameter at breast height (dbh) was measured as well. Results showed that average density of the host trees of different microhabitat types at managed and control compartments were 28.12 and 26.66 per hectare, respectively and the difference was not significant, based on t-student test. Average number per hectare of different microhabitat types at the managed and the control compartments were as follows, respectively: burst bark: 0.6 and 3, snag: 5.6 and 11.5, deadwood: 5.6 and 5.4, woodpecker: 4.4 and 5.4, broken tree top: 5 and 0.8, conks: 0.6 and 1.5, uprooted Stumps: 0.6 (only in the managed compartment), cavities or scars 10 and 3.8. Results of Mann-Whitney test showed that there was only significant difference between the compartments in respect to their average number of cavity or scar trees. Although there were not significant differences between the two compartments in respect to their host trees number at different diameter classes, but the number at the managed compartment at diameter classes of 30 and 60 cm was greater than that one at the control compartment, whereas the number at 90 cm. diameter class at the control compartment was greater than that one at the managed compartment. Furthermore, Carpinus betulus in the managed compartment and Fagus orientalis in the control compartment were host of more microhabitats. Fagus orientalis was host of more diverse microhabitats in both compartments.

This research was carried out to compare two oak (Quercus brantii) stands (healthy and affected by oak decline) in respect to characteristics of competitive environments in Shalam Forest، located at north of Ilam province of Iran. The study area was divided into 20 topographical homogeneous units، using GIS method. Considering the dieback rate at the units، five homogeneous units with different dieback rates were selected. After that، six transects (100 m. length) were allocated at each of the units and five points were laid on them at 25 m. intervals، using the systematic random statistical method. The two closest dead and alive trees to the points were identified. Finally، some characteristics of the focal trees around the two selected trees were measured and recorded، including their distance to the focal trees، species، crown diameter and total height. Competitive condition of the focal alive and dead trees in the stands was computed by Hegyi index. The data were analyzed، using ANOVA and t-test statistical methods. Results showed that there was significant difference between the homogeneous units in respect to the tree''s competition rate. According to the t-test results، competition rate of the dry and almost dry trees was greater than that of the healthy or less dried trees. The lowest and the greatest tree competition rates were found in the homogenous units with lowest and greatest crown dieback rate، respectively. The focal dieback trees had lower crown diameter، total height and distance to the neighboring trees in comparison to the focal healthy trees، whereas the neighboring trees to the focal dieback trees had greater crown diameter، total height and density. It might be concluded that tree''s competition rate has direct correlation with stand or tree groups density which varies، depends on available soil moisture content and competitive stress at different parts of the stand. The results of this research can highlight importance of tree competition، dependant on stand density as a predisposing factor of oak trees mortality at drought conditions، occurred at recent years and can be useful for rehabilitation management of the oak forests under dieback condition.

One advantage of artificial neural networks is application in the management and planning of natural ecosystems. Considering the high biological diversity of northern forests of Iran، it is necessary to know forests ecosystems. Thus، using artificial neural networks is important for modeling and forecasting of presence and abundance of wood macrofungi in forests. Fungi samples were collected in summer and fall seasons on oak and hornbeam trees from compartments 110، 207 and 311 in educational and research forest of the University of Tehran. Totally 231 samples of macrofungi were collected that 112 samples of them belong to wood decay fungi. Results showed that the designed artificial neural network، has suitable potential for modeling of abundance of wood fungi. Network with two hidden layers and 11 neurons in each layer with the highest coefficient of determination، show the best performance of topology optimization. The number of inputs and outputs equal to 112 samples with 11 variables including density class 4 or class of fungi. Sensitivity analysis showed the decay stage of tree، tree health status and its condition and stand microclimate have the most effect on presence and abundance of wood macrofungi.

This research was carried out to predict potential distribution of Armardeh forests types (16482. 44 hectares). Determination and classification of forest types was made، based on data of 448 circular sample plots (0. 1 hectare area). Eight forest types were identified، in which four types، including “Quercus infectoria- Quercus brantii”، “Quercus brantii-other species، mixed with Quercus infectoria”، “Quercus brantii، Quercus libani mixed with other species” and “Quercus brantii” were modeled using physiographical factors. Modeling was performed by both logistic regression and stepwise methods (likelihood ratio)، using 70% of the samples for modeling and 30% of them for model validation. Results showed that the achieved models for the forest types with limited distribution range، had more accuracy than the other types. According to ROC curve test، the greatest precision was allocated to models related to “Q. brantii”، “Q. brantii، Q. libanii mixed with other species”، “Q. brantii -other species، mixed with Q. infectorai” and “Q. infectoria- Q. brantii” forest types، respectively. Furthermore، due to presence of aspect in most of the models، it was distinguished as an important physiographical parameter in local forest type''s distribution. Overall، according to positive and negative correlation between presence of each forest type with variables which take part in the logistic model process، its accordance with results obtained from forest type map adaptation with other studied parameters، and further similar research results، it might be concluded that logistic regression is an appropriate method to study effects of different factors on spatial distribution of various forest types. Forest types predicted probability maps، could be used as a management tools for development and rehabilitation of forest ecosystems.

Nitrogen-fixing trees (NFT) or trees that have the ability to sequestrate nitrogen in soil، could increase organic matter in the understory’s soil. These trees can increase fertility of soil by adding large amount of nitrogen to soil and also supply necessity of the understory’s plants or NFTs to this element. This study was conducted to investigate the role of “Celtis caucasica” as nitrogen-fixing tree on understory’s soil fertility and plants in a reserved area called Ardasteh-Dehaghan at Isfahan province of Iran. For this reason، soil sampling was made from two locations (the tree’s understory and outside it or control) and three depths from soil surface (0-20، 20-40 and 40-60 cm) under the randomized complete blocks statistical design. The studied soil properties consisted of: pH، EC، CaCO3، organic carbon، mineral nitrogen، total nitrogen and particle density. Furthermore، a criterion plant from the tree’s understory was analyzed at laboratory scale to test effects of the trees on amount of total nitrogen، protein and plant production. Results showed that the greatest amounts of soil’s lime، mineral nitrogen and total nitrogen as well as the criterion plant’s organic carbon، total nitrogen، protein and production was gained at soil depth of 0-20 cm of the hackberry’s understory. These amounts were reduced as soil depth increased.

Forest harvesting is one of the most important objectives of forest management، in which it will cause damages to the residual stand، using any of the current methods، but the improved harvesting methods might reduce these effects. One of these methods is application of the directional felling. It was tried to investigate effect of directional felling on number of damaged trees at both felling and winching processes، as well as on felling and winching times. Observation and measuring was made in Neka-Choob Company’s forests. Overall، 84 trees were selected from the total marked trees، from which 42 trees were painted before the felling operation to specify the cutting and the felling direction on them by the project supervisor support. The time required for cutting and winching operations and number of the damaged trees at both operations were recorded. Results showed that the average net time required for the cutting operation at directed trees was 2. 95 minutes per tree whereas it was 4. 04 minute per tree for undirected trees. Furthermore، the number of the damaged trees with diameter greater than 10 cm at the undirected felling was more than the directed felling method (100 vs. 25 trees). In addition، winching time at undirected trees was more than two times in comparison to directed trees and more residual trees were damaged at undirected felling method at winching process (50 vs. 14 trees).

Tractor-based logging systems are the most common type of small-scale equipments. Farm tractors equipped with a 2-wheel trailer are mostly used to perform forwarding operations of pulpwoods and fuelwoods in the Hyrcanian forests of Iran. This study was carried out in Gorazbon district of Khyrud forest. The aim of the study was to evaluate effects of slope gradient، tractor traffic intensity over skid trails and soil depth on brown soil bulk density (BD)، total porosity (TP) and penetration resistance (PR) with clayey loam to loamy texture. The trial was conducted under the completely randomized factorial design at three replicates and three treatments، including: three slope gradients (0-10% (downhill)، 10-20% (downhill) and 0-10% (uphill))، three traffic intensity classes (<5، 5-10 and >10 passes) and four soil depths (5، 10، 15 and 20 cm) on skid trails and undisturbed locations adjacent to the study area. Results indicated that mean BD was significantly influenced by slope gradient، traffic intensity and soil depth. Skid trail on the uphill tractor forwarding slopes، showed the greatest value among the other ones. Results showed that TP significantly decreased as number of machine passes increased and high level of decrease occurred after further than 10 machine passes performed (TP= 38. 6%). Skid trail on the uphill tractor forwarding slopes showed the greatest PR value among the other ones. Penetration resistance increased significantly by increase in soil depth under the skid trails. Skid trails with 0-10% slope (downhill) had the lowest BD and PR values، whereas the trails with 10-20% slope (downhill) had the moderate values and the trails with 0-10% slope (uphill) had the highest compaction values. Overall، it might be concluded that forwarding operations with farm tractor should be planned in gentle slopes and uphill forwarding should be excluded from ground-based logging systems، if it’s possible.

Taxus baccata is a native endangered coniferous species of Iran. Although the species had a wide range distribution in the past، but now has limited habitats. Therefore، further studies of the species spatial distribution and its possible development and extant by plantation projects، is necessary due to vital support of this medicinal species. The aim of the study was to compare the Yew’s ecological requirements with the ecological characteristics of the studied area at Golestan province in order to identify the most appropriate sites for forest plantation. For this reason، the multi-criteria evaluation (MCE) method، based on analysis of hierarchical process (AHP) was used. At first، the 10 required natural criteria which affect T. baccata’s growth، including altitude، slope gradient، slope aspect، geology، relatively air moisture، precipitation، temperature، soil type، plant cover and canopy cover density were considered and at the end after identifying their weight، final map of the area suitable for the Yew’s plantation was developed، based on the Multi Criteria Evaluation model. The results showed that from the studied total area of 30554 hectares، the classified lands for the Yew’s plantation were as follows: 2482 ha. Excellent، 10982 ha. fine، 10909 ha. moderate and 6181 ha poor. Overall، it’s easy to specify the areas suitable for Yew’s plantation as well as to develop a registered program and plan for its plantation at the Caspian forests of Iran.

Islamic Republic of Iran''s forest products export market at time interval of 1970 to 2009 was investigated، using comparative advantage indices. Based on application of Revealed Comparative Advantage (RCA) and Revealed Symmetric Comparative Advantage (RSCA) indices and Stability Export Performance، results showed that the country had a non-comparative advantage in forest products export issue and the country''s trade movement in respect to forest products export was subject to numerous fluctuations with descendant and negative growth. Overall، in order to increase the forest products exports and have benefits in Export Comparative Advantage، the following comments were suggested: 1- Study the intended commercial perspectives such as identifying the target markets of these products. 2- Cession of forest resources to private sector، in order to increase forest exports via increasing forest products

In forestry، human seeks to achieve a new ecological system which suits local conditions. The aim of the research is to investigate soil carbon sequestration and its economic value، herbaceous cover biodiversity of the studied forest plantation stands and introduce factors affecting carbon sequestration. In order to measure biodiversity in five stands، 10 healthy and dominant trees were selected at each stand and 1 x 1 m. plots were allocated under each canopy cover (at four geographical aspects) and out of it at north aspect Sampling was made from soil surface beneath each tree''s canopy cover. The results showed that the greatest species according to the studied criteria، using Analytical Hierarchy Process، were Pinus brutia، Cercis siliquastrum and Fraxinus excelsior، respectively and they are recommended for forest plantation at similar ecological conditions. Furthermore، step by step regression analysis showed that gravel %، moisture %، bulk density and organic content % are the most effective parameters for carbon storage.

Carbon sequestration rate of forest trees and their spatial pattern are prominent factors which affect global carbon dynamic and can be basically applied to predict climate change. For this reason، compartments2 and 4 of district3 of Glandrood Forest were selected for this study and few disks (2 cm thick) were sampled from each felled oak tree at 2-5 m. interval of its bole. Further samplings were made from each disk at constant volumes (3x3x3 cm) and intervals (2 cm). The samples were oven dried in lab for 24 hours (105°C) in order to determine their dry density. Carbon factor was obtained directly by exposing the wood samples in the oven and was estimated، based on organic carbon/organic material ratio. Compartment3 of district3 (38 hectares) was selected as a control due to its undisturbed and virgin characteristics، to determine carbon sequestration of the oak trees and their spatial pattern in relation to the physiographical units. After that، 400 m2 sampling plots were allocated in the compartment، using the random systematic method at 100 m. grids، then diameter at breast height and total height of the aimed trees were measured. Carbon sequestration was estimated، using the volume x dry density x carbon ratio equation. The results of one-way Anova analysis showed that although there was significant difference between the dry wood density values at different intervals، with respect to pith to periphery (bark) of cross-section of disks (P < 0. 01)، but there was no significant difference between the individual oak trees at different diameter dimensions (P > 0. 05). As the average value of oak wood dry density is 0. 81± 0. 0083 g. cm-3 and average carbon factor is % 57. 37 ± 0. 108، so according to the results of Paired-Samples t test، the values of calculated carbon sequestration were significantly more than the estimated values (P < 0. 01) and their difference was 4. 267 ± 1. 39 t / ha. Overall، the result of one-way Anova analysis showed that there was not significant difference among the carbon sequestration values of the oak trees at various physiographical units (P >0. 05) which indicates that the spatial pattern of carbon sequestration values in the oak bole trees at the aimed study area were not associated with the environmental physical affects.

Regarding the importance of Zagros forest ecosystems and the recent wildfires، interaction between fire severity and soil properties and macrofauna was investigated in this study. For this purpose three burning severity levels including: low (occurred at forest floor or outside oak sprout clumps)، moderate and high severity (occurred inside the oak sprout clumps) were considered and compared respectively to control plots inside and outside the oak sprout clumps. Fifteen 0. 5 × 0. 5× 0. 2 m. sample plots were randomly selected for each above-mentioned treatment along transects in the both burned and control blocks. Sampling was performed for two times، including 13 months (autumn) and 20 months (spring) after fire. Soil macrofauna were hand sorted and classified after their determination. Results indicated that low burning level changed neither the soil properties nor the macrofauna total number، whereas high burning level changed significantly both the macrofauna total number and the soil properties. Presence of earthworm and silverfish was positively correlated to litter thickness، soil organic carbon، nitrogen and moisture، based on canonical correspondence analysis (CCA)، whereas elimination of earthworm and silverfish was positively correlated to decrease of the soil and litter properties at moderate and high burning levels.

Intentional and unintentional fire occurrences are known as main threat factors of Zagros forests which destructed wide areas of these forests in recent years. Investigating and offering management solutions in this respect can play a controller role in tackling this crisis. The aim of the study was to identify and evaluate the most important factors influencing forest firefighting techniques in Marivan forests، using SWOT technique. Due to variation of fire control management solutions، they were classified into two categories، risk and crisis management. Identification and specification of the affecting criteria on fire control was employed، using an open answer-sheet method، based on stockholder analysis. Then the obtained results of SWOT technique were quantified by AHP approach. Results showed that employment generation and income، on-time accessibility and staff efficiency (overall weight of 0. 106، 0. 069 and 0. 068، respectively) were identified as the most important factors affecting crisis management solutions. Furthermore، prevention of fire expanse in forest، action speed and possibility of job generation (overall weight of 0. 123، 0. 120 and 0. 118، respectively) were identified as the most important solutions for risk management. It is recommended to: 1- reconstruct and improve the local societies morale to their surrounding environment، 2- develop the villagers culture، 3- develop national decision for natural resources conservation and finally 4- avoid absolute governmental management and administration for appropriate and scientific control of forest fire.

In order to determine the most suitable water storage method and irrigation interval level on growth and primary establishment of Prosopis cineraria and Ziziphus spina-christi، a trial was conducted under split plots experimental design based on randomized complete blocks، with four replications at Dashtyari territory of Chabahar township (south of Sistan and Baluchestan province of I. R. Iran) for five year period to support reforestation projects. The main factor was water storage method at two levels (turkey nest and terrestrial dam) and the sub factor was irrigation interval with three levels (10، 20 and 30 days). The terrestrial dam and irrigation interval treatments were chosen as control due to local conventional conditions. Results showed that the 10 day irrigation interval was the most suitable treatment for the species establishment and it increased the seedlings survival، growth and establishment significantly. Survival and establishment of P. cineraria was significantly greater than Z. spina christii. Effects of turkey nest and terrestrial dam on survival and species characteristics were often not significant، whereas effects of terrestrial dam on the species vegetative characteristics and establishment were greater than the other treatment.

Populus euphratica Oliv. is one of the important poplar species which regenerate mainly through asexual reproduction، for which there is not enough genetic variation within its plant populations. This work investigated several morphological and micro-morphological traits on four half-sib progenies of each eleven parental clones of the species which was grown in a collection at Alborz Research Station، located at Karaj، Iran، as new produced genotypes. Therefore، 44 new clones of progenies of 11 parental clones were studied، based on a nested statistical model for the traits. Results indicated a vast variation between the studied parents and their progenies that may be used to produce new commercial varieties of the species. Average performance of the studied progenies increased on the traits such as leaf length and width، of which leaf area would be increased; resultantly this would improve plant photosynthesis. The higher performances of the progenies for the traits imply a suitable potential for selecting the genotypes with higher performance within the new produced progenies. Petiole length and leaf width showed a significant positive correlation to stomata length as well as significant negative correlation to number of stomata. Regarding the role of stomata on plant photosynthesis، the correlation values may be used for indirect selection of suitable genotypes of the species.

The aim of the study was to develop forest plantation at appropriate sites of Bushehr province for environmental purposes and to extend olive plantation on marginal lands for economical purposes and to improve local people livelihood. For this reason 12 varieties of Olea europaea including Arbakin، Zard zeitoon، Roghani Roodbari، Mari، Mishen، Lichio، Lemski، Shengeh، Sabz Zeitoon، Sevilana، Beledi and Manzalina were planted on a site located in Chahvak Agricultural Experimental Station in 1997 under statistical design of Randomized Complete Blocks with three replicates and 7 x 8 m. spacing and 10 seedlings per plot. The variance analysis and Duncan test were applied to analyze the data. The data analysis showed that there was significant difference (p<0. 05) between the olive varieties in respect to total height، survival، fruiting percentage and Crown cover area. According to Duncan test، the results are as follows: - Survival: The greatest values belonged to Lemski، sabz Zeitoon، Sevilana، Lichio and Roghani varieties (100 %) and the lowest value belonged to Beledi variety (60 %). - Crown cover area: The highest values belonged to Sevilana and Roghani Roodbari varieties (10. 6 and 9. 8 m2، respectively) and the lowest value belonged to Shengeh variety (4. 6 m2). - Fruiting: The greatest values belonged to Shengeh and Mishen varieties (97. 5 and 57. 8 %، respectively) and the lowest values belonged to Sabz zeitoon، Lemski and Manzalina varieties (2. 5، 2. 5 and 5 %، respectively). - Total height: The highest values belonged to Roghani and Sevilana varieties (3. 3 and 3. 2 m.، respectively) and the lowest value belonged to Shengeh variety (2. 3 m.).