FOREST RESEARCH AND DEVELOPMENT
Year:2020 | Volume:6 | Issue:1|Papers Count:11

In the present study, the response curve of box tree to some edaphic characteristics (texture, nitrogen content, carbon content and pH) and physiographic factors (slope, aspect, and altitude) were analyzed in the Hyrcanian forests using random forest algorithm. For this purpose, 857 sample plots (400 m 2 ) were established in the large habitats of B. hyrcana as selective method. The response curve of B. hyrcana Pojark showed that acidity and altitude are the most important and aspect and silt content are the least important variables. Also, based on the ecological optimum values for each variable showed that the Buxus tree is lime-and moisture-demanding species, which is present in low altitudes, steep slopes and light soils with high nitrogen content that can be used for the management decisions. The results and methods presented in the paper can also be applied to conserve and restore the other rare and endangered species.

The present research aimed to investigate effects of social capital on stakeholder's participation in Tang-e Sulak watershed in Likakin county of Kohgiluyeh and Boyerahmad province. The research method was descriptive-applied and conducted using stratified random sampling method. Study population included rural households in eight villages (N=754). Based on Morgan's sample, 256 persons in selected households have been interviewed as the sample size. Results showed that relational aspect of social capital and also conservation aspect of participation were at top priority. There were significant relationships between social capital and number of household members and education. Furthermore, significant positive relationships were found between age, duration of residence number of household members, ranching experience and agriculture experience with participation in forestry plans.

This study was carried out to study the habitat characteristics of Persian juniper trees due to the topographical factors and site exposure in Spiro forest habitat, located at Damghan County. Inventory done by systematic method (Net dimensions: 300×400m). Trees number and diameter at breast height in 10 R area sample plots were taken. Then, the topographic factors effects on some of the growth variables of Persian juniper stands such as basal area and number per hectare were evaluated using stepwise regression model. The results showed that three indices of aspect, site exposure and topographic wetness had a positive and significant correlation with the number of hectares of trees. Also, elevation from the sea level, site exposure and roughness had a positive and significant correlation with trees basal area variable per hectare. According to the results, the most correlation between cypress quantitative characteristics, including number per hectare and its basal area, was obtained by topographic factor of site exposure.

In the present study, the effects of three type of Iranian hardwoods (Beech, Hornbeam, and Alder) on the vibration level and characteristics of Stihl-MS230 chainsaw were analyzed and the results were compared together and to the control sample (without cutting). The vibration acceleration on front and rear handles of chainsaw were measured in three perpendicular axes based on ISO 7505 (1986) standard. The total root mean square (RMS) acceleration and frequency-weighted vibration acceleration (Ahw) were obtained from acceleration-time spectrum and acceleration-frequency spectrum respectively in accordance with guidelines of ISO 5349 (2001). The results indicated that the effect of operational mode, axis, and interaction between them on the RMS acceleration were statistically significant (p˂ 0. 01). Also, the effect of operational mode, position, axis, and interaction between them on the Ahw were significant (p˂ 0. 01). However, Ahw values of different woods were not found statistically different (p>0. 05). Analysis of RMS acceleration revealed no significant difference between handles (p>0. 05). While, frequency-weighted vibration acceleration of rear handle was significantly more than that of front handle (p<0. 01).

This study aims to determine the floristic composition and investigate the distribution of communities along an altitude gradient in oak forests of Taf in Khoramabad. The study area was classified into 100m elevation classes, and in each class two 500m2 plots were chosen randomly for measuring trees and shrubs layer. Also in each 500 m2 plot three 4m2 plots were distributed for measuring herbaceous layer composition. Changes in vegetation along an altitudinal gradient were studied using slope, altitude and some edaphic data by CCA, DCA and TWINSPAN ordination and classification methods. Based on the results, 116 species from 35 genera were observed along the altitude gradient. Asteraceae, Poaceae and Fabaceae families had the most species respectively. Therophytes, Hemicryptophytes and Cryptophytes were the most dominant life forms and Iran-Toranian and Iran-Torani-Mediterranean were the most chorotypes in this area.

The purpose of this study was evaluation the effects of nanoparticles (nano-cellulose, nano-chitin, nano-chitosan, nano-silver and nano-copper) on the control of disease fungal agent in-vitro conditions. Factorial experiment was carried out in a completely randomized design with three replicates and five concentrations (0, 50, 100, 150 and 200 ppm) for each nanoparticles. Results showed that the using of nanoparticles with the mentioned concentrations in inhibiting the growth of mycelium fungi was significant in box blight and nanoparticles had a significant effect on the growth of mycelial fungi growth. The results of comparison of meanings showed that nano-silver had the most effect and nanocellulose had the least effect on reducing the colonization diameter of fungi. Among the various concentrations tested, the concentration of 200 ppm had the highest effect on the growth of the colony of the fungus, while the concentration of 50 ppm has the least inhibitory growth of of the colony of the fungus. The results showed that application of different concentrations of nano-cellulose and nanochitin had little effect on inhibiting the growth of colony of fungus caused by Calonectria pseudonaviculata. Meanwhile, nano-copper, nano-silver and nano-chitosan were able to inhibit growth of 200 ppm in 83. 1%, 78. 8% and 64. 9%, respectively. Results showed that using nanoparticles with mentioned concentrations had significant inhibitory effects on fungal mycelial growth. The results of mean comparison showed that nano-silver had the most effect and nano-cellulose had the least effect on reducing fungal colony diameter. 200 ppm concentration had the highest effect with maximum fungal growth inhibition. On the other hand, 50 ppm concentration showed the least inhibitory effect on fungal mycelial growth. The results showed that using of nano-cellulose and nano-chitin different concentrations had little effect on fungal colony growth inhibition.

This research attempted to assess and provide information about biodiversity and distribution of urban tree species by applying several biodiversity indices, including richness, per area estimates of number of species, Shannon-Wiener, Menhinick, Simpson diversity, Shannon-Wiener evenness indexes, evenness index and Sander’ s rarefaction technique and also analyzing native and exotic species using i-Tree Eco model both at the city scale and land use classes. Forty-eight species identified among the city. It is estimated that Tabriz had 192800 trees with the 9. 4% tree cover. There were 3. 6 trees per hectare. The Shannon-Wiener, Menhinick, Simpson diversity and Shannon-Wiener evenness indexes calculated as 2. 9, 1, 12 and 0. 8 for the whole city, respectively. The green space and agricultural lands had the highest richness. Commercial, transportation and industrial land (CTI) included the most species per hectare. Also, residential areas had the highest value of Shannon-Wiener and Menhinick diversity indexes. The 37. 5% of the species was endemic to Azerbaijan.

Determination of the sprouting potential of the Quercus brantii, the relationship between the shoots variables with the stump diameter and the number of shoots in each stool are the objectives of this study. For these purposes, a total of 93 stumps in the coppicing stands in Chaharmahal and Bakhtiari Province were selected in a growth period of personal protection. The logistic model was used to determine the potential for sprouting with age and stump diameter variables. The relationship between the shoots variables with a different model (linear and non-linear) was investigated. The results of the logistic model showed that a model including the stump diameter is the appropriate model for determining the potential of sprouting. The polynomial model in terms of model selection criteria among other models showed better results for estimating the three variable include dominant heights, mean height and number of shoots in each stool. The highest coefficient of determination (R² adj = 0. 639) and the best result for the selection criteria of the model were the numbers of shoots per stool with the stump diameter. The results of ANOVA analysis showed that there were significant differences between different diameter classes. There is no significant difference between 5-25 cm and 25-55 cm diameters classes.

The aim of the study was to provide an intelligent artificial neural networks-based method for modeling the capability of Arasbaran protected area for road crossing, in order to design, modify, and appropriate development of existing road network and communication routs in the region. First, using Analytical Hierarchy Process (AHP) and Weighted Linear Combination (WLC) method, and utilization the effective informative layers on routing, the suitability map of road construction was prepared to provide training samples in ArcGIS. In the following, Multilayer Perceptron (MLP) network was used to estimate the suitability value of road crossing. In order to evaluate the neural network’ s model performance, the results were compared with the results of multivariate linear regression. According to the results, artificial neural network and statistical method of regression were shown to be useful in determining the suitability value of road crossing with coefficient of determination (R2) 0. 908 and 0. 901, root mean squared error (RMSE) 0. 0385 and 0. 04, respectively. Neural network results were relatively better than regression. Also, according to the results of sensitivity analysis of input variables, four criteria of slope, bedrock, erosion susceptibility, and soil texture showed the highest influence in estimating the model, respectively.

Several factors play an important role in the occurrence of fire in forests. So accurate prediction of the time and place of the fire is difficult, but using the GIS, it is possible to identify points of high fire risk. The purpose of this study was to investigate the possibility of preparing a fire hazard zonation map for Ilam district. Socioeconomic, climatic, topographic and vegetation factors were considered as suitable criteria for assessing the status of fire risk of these forests and were evalutaed Using satellite imagery data, geographic information system and neural network system. According to the results, the variable of distance from cities with a weight of 100% is the most influential variable in creating fire and height variable with a weight of 1. 5% as the least important variable in the occurrence of forest fire in study area. Based on the results of the assessment of the accuracy of the fire hazard zonation map using the error matrix, it was found that the produced map with a general accuracy of 73. 73% is highly true. Also, based on Kappa agreement coefficient (0. 77) between the map and actual fire data, it can be concluded that the map prepared with the actual data was highly adapted.

In order to provide quantitative characteristics of the oak forests structure, a six-hectare area was selected in the Shine Qalaee area of Lorestan province and the structural diversity of tree communities was investigated using the nearest neighbor Method. The Clarke-Evans, mingling, diameter and height differentiation and distance indices were employed to quantify the structure of oak forests. The mean of diameter, tree height and number of shoots per cohorts was 38. 8 cm, 2. 50 m and 11. 33 tree, respectively. Also, the mean of mingling, height differentiation, diameter differentiation was calculated 0. 33, 0. 21 and 0. 12 respectively. Tree to tree interval was 4. 07 m and Clark-Evans was 0. 9. Results revealed that tree species spatial pattern was clumped associate with low diversity of species and relatively homogeny in tree dimension that distance increase cause to falling down in diameter differentiation and raising up tree vitality. Accordingly, we could conclude that oak trees in natural habitats tend to have low diversity and high inter-species completion. In order to maintain structural diversity of stands we suggest enclosing and restoration operation in studied sites.