مجله جنگل ایران
سال ششم شماره 4 (زمستان 1393)

Sowing seeds is the most common method for forest rehabilitation، for this reason، the success in sowing is very important. Sorbus greaca and Acer monspessulanum growingin Zagros and Iran-Tourani zones are important because they tolerate very harsh conditions and make plant cover. One of the most important issues in seedling production is low percent of seed germination. Finding solution for seed germination without negative environmental effect with less charge has great importance. The effects of indole acetic acid (auxin) producing bacteria، nitrate potassium and giberllic acid treatments were determined on two forest species including Sorbus greaca and Acer monspessulanum. Forthis purpose، indole acetic acid (auxin) producing bacteria was isolated by dilution and screening method and identified by microbiological methods. Collected seeds were sterilized and treated by mentioned treatments and incubated at 4 C. There was a significant different between control and treated seeds in Acer but no difference was seen among treatments. Results indicated a significant different between KNO3 (5000ppm)، Citrobacter and Alcaligenese treatments and control and other treatments in Sorbus seeds germination. In conclusion، there is possibility and potential to use microbial treatments alone or with other environmental friendly method to increase the seed germination or decreasing seed dormancy period.

The present study aimed to evaluate the capability of IRS-P6-LISS III imagery to map a forest canopy density by employing the traditional hard classification and the Artificial Neural Networks (ANNs) in Marivan city، Kurdistan province. Geometric correction procedure was performed with less than 1 pixel root mean square error (RMSE). Various vegetation indices and artificially bands generated by principal component analysis (PCA) were used in the classification procedure. A ground truth map was produced based on a randomized-systematic method with a grid size of 250×400 meters and 50×50 meters sample size strata. The suitable band combinations for classification were selected through the training area using the Transformed Divergence index. Supervised classification methods i. e.، parallelepiped، minimum distance to mean، maximum likelihood، and ANNs algorithms were applied to generate the canopy density map with 4 classes (very sparse، sparse، semi-dense and dense). The accuracy assessment of the generated canopy density maps was implemented using the ground truth map. Some classes were also merged because of the low spectral separation between these classes. Finally the classification was performed to produce the canopy density map with 3 classes (sparse، semi-dense and dense). The highest overall accuracy and the Kappa coefficient were achieved by maximum likelihood method with 78. 47 percent and 0. 66، respectively. Our results indicated the high capability of the IRS-P6 LISS III imagery compared to other satellite images، for example، Landsat and Aster data، which already tested in the previous work to map the canopy density in Zagros forests.

The present study investigates how the concession for the exploitation of north forests of Iran was submitted to Russian company “Koosis Teofeelucktous” as well as its consequences and effects on the under- utilization forests. For the first time in this research the exploitation and degradation of the forests by the foreign companies are studied from the historical point of view. So this study can be considered as a step toward the development of the interdisciplinary in historical and environmental issues. The main goal of this research was to identify the influential factors in submitting this concession and its economic and environmental consequences due to the inefficient and corrupting government of Iran as well as colonial policies of the foreign companies relying on the growing western capitalism. In this study، the historical research method is applied based on the acquisition of the required data through historical original documents and descriptive analysis. The results showed that the lack of knowledge and utter neglect of Iran''s official authorities regarding the forest resources as well as the colonial dominance of the authoritative governments and the corruption of Iran''s officials are the main causes behind these agreements and concessions. However، breaking the substances of the agreements was made easier thanks to Iran’s government negligence. Hence، the way of forests exploitation leads to the serious damages and degradations.

Plants as bio-materials in addition to having self-renewal capability، cause no adverse effects on the environment. Vegetation in steep areas have an important effect in the process of soil erosion and its control in comparison with bare soil and therefore plays an important role in improving the stability of the slope. The effects of vegetation in slope stability and hydrological processes depend on tensile strength of roots and determining root tensile strength will provide the information required to analyze the role of roots in the soil improvement. The purpose of this study was to investigate the root tensile strength of Persian oak and comparing its values ​​in leaf on and leaf off seasons. To do this، a relatively uniform hill was selected، root samples were randomly collected from 5 oak trees and tensile strength was measured using a standard Instron. 224 successful tensile tests were conducted with root diameter range of 1. 0- 5. 5 mm، tensile force range of 1. 3-411. 3 N and tensile strength range of 0. 93-1217. 39 MPa. The relationship between root diameter and tensile force and strength were positive and negative power law، respectively. The results of Wald test showed that the difference in tensile strength due to season is significant and the mean strength was higher in winter than summer. The covariate (root diameter) was also statistically significant. This phenomenon may be a mechanism of root system adaptation due to the increased soil moisture content and reduction hydrologic effect of vegetation.

The main objective of this study was to evaluate the relationship between environmental factors and arbuscular mycorrhiza fungi (AMF). For this purpose، soil samples were randomly collected in the rhizosphere of almond trees (from 0-30 cm) in the Meleh-Ruteh region، Darehshahr city. There were 7 species of AMF including; Glomus fasciculatum، G. intraradices، G. mosseae، G. claroideum، G. drummondi، G. caledonium and Gigaspora giganteain this region. Two-way indicator species analysis (TWINSPAN) distinguished two different groups that G. fasciculatum and G. caledonium were the indicator species of the first and G. mosseae، G. drummondi and Gi. gigantea were the indicator species of the second group. Also، DCA analysis showed that the first group had positive correlation with clay and bulk density، while the second group had positive correlation with sand، organic matter، total nitrogen، magnesium and litter depth. The results also showed that colonization and abundance of spores had positive correlation with total N، organic carbon، potassium، litter depth and tree height and negative with silt، phosphorus and bulk density.

Canopy gaps have an important role in constitution of the forest stand composition and natural regeneration establishment in the forest ecosystems. In the single selection method، forest manager try to improve the forest regeneration by the creation of gaps in the crown canopy layer. This study was carried out in the Kheyrud forest to investigate the characteristics of established seedlings within natural and artificial gaps. The study was done in sixty canopy gaps. Gap properties including gap size and shape were precisely measured. The main objective of research was to discover the relationship between abundances and height of seedling with gap properties. Results showed that in the natural canopy gaps، total abundance of seedlings correlated with gap size، moreover beech seedlings density correlated negatively with size of gaps. Meanwhile there is no relationship among density and height of maple، hornbeam and minor species seedlings. Canopy gap shape in natural and artificial gaps correlates significantly with total density of seedlings. Also oriental beech constitutes more than 90 percent of definitive gap fillers. The comparison of total number of seedlings and sapling in different size classes in the natural and artificial canopy gaps revealed significant relationship between size of gap and seedling density. According to our findings، we strongly recommend that forest manager to consider the size and shape of canopy gaps in single tree selection method.

In this study، Pinus nigra forest plantation with an area about 10 hectares، located in Urmia airport was investigated. Sixteen 300 m2 circular sample plots were set up with systematic random method in 50×50 m grids network. One 100 m2 subplots، within the same plot، were established to record plant species and its cover. Soil samples in two depths (0-10 and 10-30cm) were taken in every other samples and soil factors including pH، soil organic carbon، total nitrogen، absorbable phosphorous were measured. Also a rangeland adjacent to plantation area was selected and three plots with 50 m distance spacing were laid out along a transect. Herbaceous species and soil factors were assessed in each plot similar to plantation area. The mean of diameter and height annual increment was calculated via dividing the diameter and height means by stand age till study time (40 years). Species richness and diversity indices were calculated in each plot. T-student test was used to test for significant differences between the means of indices and soil factors of two areas. Non-metric multidimensional scaling was applied to assess the rate of changes on the vegetation and soil chemical properties due to the plantation. Results showed that the mean diameter and height increment were 0. 46 cm and 0. 29 m، respectively. Species richness and Shannon diversity indices considerably decreased in the plantation area. The average of soil organic carbon، total nitrogen in the control area were more than those of the plantation area. Light، soil organic carbon، total nitrogen and absorbable phosphorous were the most important factors influencing the distribution of plant species. Generally، it is suggested that this species would not be planted in the wide regions and in the region in which it’s necessary to conserve plant composition and diversity.

Riparian forests maintain diverse vegetation structure through the influence of various types، intensities، and frequencies of disturbance promoted by fluvial and geomorphic processes. These fluvial and geomorphic disturbances vary longitudinally from headwater streams to low-gradient alluvial rivers and result in different types of plant communities according to longitudinal location. The aim of this study was to investigate on the floristic composition، life forms and chorology of all plants along Safa-Rud riverside between 350-2400 m a. s. l in Ramsar forest. The final results of the studies on floras showed that 260 plant species belonged to 226 genera and 77 families. The Dicots with 204 taxa were the richest group of flora followed by monocots with 41 taxa، Pteridophytes with 13 taxa and Gymnospermae with 2 taxa. Dominant life forms include Hemicryptophyte (38. 37 percent)، Geophytes (23. 55 percent)، followed by phanerophytes (18. 6 percent). From the chorological point of view، the largest proportion of the flora belongs to the Euro-Siberian elements (23. 25 percent) followed by Pluriregional elements (21. 7 percent)، Euro-Sibirian/ Irano-Turanian (18. 6 percent) and Euro-Sibirian/ Irano-Turanian/ Mediterranean (15. 11 percent). Riparian Forest are severely degraded especially by human factors، thus a careful planning is needed to protect them.