فصلنامه تحقیقات جنگل و صنوبر ایران
سال شانزدهم شماره 3 (پیاپی 33، پاییز 1387)

This research was carried out to identify the site demands and silvicultural characteristics of Caucasian false walnut in Lorestan province, south western of Iran, far from its common natural habitat in northern Iran. Considering the small distribution area of this species, 100% inventory of qualitative and quantitative characteristics of all trees were made. Moreover, the climatic condition and soil properties of the stand were studied. Results showed that climate of the studied area is semi-humid and cold. The stand appears at a stream terrace in the calcareous bedrock, clay loam soil with a pH of 7.5. Almost 58% of trees were coppice while only 42% had seed origin. The minimum and maximum diameter of false walnut trees were 2 and 28 cm, respectively. The mean annual diameter increment was calculated to 3.8 mm and the total volume was estimated to 389.5 m3ha-1. The minimum, maximum and mean height of trees were 2.3, 28 and 19.1 m, respectively. The frequency of regeneration was estimated to 15226 per hectare.

Control of weed is one of the most important problems in the botanic gardens, tree nurseries and plant research centers which generally are man made with high cost and time investment. In this investigation a wheel trimmer (brush cutter) was designed and manufactured which not only is used for weed controlling but also is applicable for seedling and bush cutting, harvesting medicinal plants and lawn mowering. The process of design and manufacturing of this machine consist mechanism selection, calculation of required power, design of the power transmission mechanism, parts design, preparing 2nd and 3rd dimensional drafts, parts manufacturing and assembling. After manufacturing, investigation on application and comparing with other methods and machines especially for time efficiency has been done. Results showed that cultivating, forage harvesting in agroforestry field, medicinal plants harvesting and mowering of old, bushy and uneven lawn are applicable and has better time efficiency compare to manual and other general methods. In bushy nurseries with high density of narrow and high young seedlings, using of this machine with circular saw blade has more efficiency in comparison to chain saw. However, in low density nurseries with thick seedlings (diameter more than 5 cm), chain saw is applicable. This wheel trimmer is a multi purpose machine with four kind knives. It is cheap, high efficient, safe and suitable for gardens, plant research centers and nurseries with low maintenance and repairing costs.

The morphology of deciduous plants changes seasonally. In addition, deciduous and ever-green plants encounter with internal changes as a consequence of seasons. Enzymes activities alter with changes of temperature, drought and salinity. Plants adapt to environmental changes with alteration of enzymes activities. In this study, the peroxidase activity was measured in leaves and shoots of Eucalyptus viminalis during a year. Peroxidase activity was measured by spectrophotometer (530 nm) by use of Worthington method. Data were analyzed to determine statistical relationship in peroxidase activity of individual trees and seasonal changes of enzyme activity by SPSS software. Results showed that peroxidase activity was different in individual trees. The difference of peroxidase activity in different individual trees was little in April, July and January but differences were higher in September and November. The peroxidase activity decreased in all individual trees from April to July. Peroxidase activity of leaves was higher than those of branches in all of studied months. There was negative correlation between some month of peroxidase activity (α<0.05). There was not any correlation between leaves and branches peroxidase activity. Individuals were classified to three classes according to their peroxidase activities using JMP software (centroid method).

In this research typology of seedlings composition and density of Fagus orientalis stands in Caspian forests of Iran (Ramsar area), at altitude of 1200-1300 m.a.s.l. within 43 gaps were studied. The gaps were created after marking and cutting the trees. The gaps area varied between 67 and 617 m2. The trial was conducted under the fully randomized design. Based on gap size and homogeneity, 1 to 3 microplots (1m2) were established in each gap. Seedling frequency was counted in each microplot, according to their species and age range (1 and 2-4 years old). The statistical methods of chi-square and ANOVA (analysis of variance) were used to analyze the data. There was no significant difference of seedling frequency and species diversity among the gap sizes. However, the number of the defined seedlings composition and density types were four and six, respectively. Beech showed the highest frequency among the species. The maximum and average densities of beech seedling were 60 and 15 per m2, respectively. 57% of gaps showed a number of 10/m2 with 1 to 4 years old seedlings.

Restoration of degraded forest areas in the Caspian region with appropriate species is very important. For this purpose two 18- years old pure plantations of Tilia platyphyllos and Acer cappadocicum with 2m×2m spacing were selected in Chamestan region. Survival and quantitative characteristics (dbh, height, volume, basal area and slenderness coefficient) as well as some qualitative characteristics (stem quality and branching mode) were investigated. Results showed that survival of maple and lime trees were 75% and 62%, respectively. The mean dbh of lime and maple trees were 17.1cm, 11.3cm, respectively. The annual diameter increment of lime and maple trees were 0.84cm and 0.6cm, respectively. Volume was calculated 214 sylve/ha for lime tree and 112 sylve/ha for maple. Basal area for maple 18.7 (m2/ha) and for lime tree 15.2 (m2/ha) were determined. Stem quality was better in lime tree than in maple. Generally, this study indicates that both Tilia platyphyllos and Acer cappadocicum are suitable species for restoration of degraded areas in the plateau of Chamestan region.

The determination of survival and vigority effective parameters on old saxaul (Haloxylon aphyllum) shrub is essential for sustainable development of planted forests in desert area. In fact, the objective of this study was to determine the effects of different density and pruning levels on survival and the vigority of saxaul. The study was carried out in obviously wilted planted saxaul forest that is located in Ashkezar desert region of Yazd province. Experiment was conducted in split plot design with main-plots that had 250 and 125 trees per ha and sub-plots were 3 types of pruning at height of 10, 35 and 70 cm above ground surface, plus control (no pruning) sub-plot. Pruning was done on autumn 1994. After one year from shrubs pruning, analysis of plant mortality percentages was started and continued on the same pruning time to 2000. The determination of vigority carried out only in 2000. Results showed that the differences of survival among all treatments were not significant. The effect of density on vigority was also not significant, whereas the pruning height had significant effect (p<0.01) on vigority of saxaul shrubs. One can conclude that the best pruning method was cutting 35 cm above ground with vigority of 43.3% and 40.9% in 250 and 125 trees per hectare treatments, respectively.

In order to investigate on deforestation modeling and correlation between deforestation and physiographic parameters, man made settlements and roads parameters in Zagros forests using remote sensing and GIS, a case study was accomplished at the Armerdeh forests, Baneh, Iran. The Landsat 7 ETM+, IRS-1C images and aerial photos were used for forest extent mapping and obtaining forest extent changes from 1955 to 2002. The forest extent map in 1955 was produced from digitizing of a digital photo mosaic of aerial photos. The ETM+ and IRS-1C images were used to generate the forest extent map in 2002. The images were geo referenced using GCPs points and digital elevation model in some steps. In addition to main spectral bands, some arithmetic bands such as some rationing transformations, vegetation indices, tasseled cap transformation, and principal components analysis were used for classification processes. Moreover, the panchromatic images of ETM+ and IRS-1D with multi spectral bands were merged using IHS and automatic statistical PANSHARP techniques. After selecting some pixels as training area for forest and non forest classes, the best set bands for classification were chosen using severability indices. The images were classified with supervised classification to forest and non forest by maximum likelihood algorithm. Results showed that using the best selected ETM+ bands could better classified forest and non forest areas than other images by maximum likelihood algorithm with 81.3% overall accuracy and 0.64 Kappa coefficient. The result of forest change detection using forest maps of 1955 and 2002 showed that 4853 ha of the forest area have been reduced and 953 ha increased in this period. The Spearman test correlation and logistic regression model were used to investigate correlation between changed forests and the mentioned parameters. The result showed that there is inverse relationship between deforestation and distance from roads. Minimum and maximum deforestation were happened at north and east aspects, respectively. The result of applying logistic regression model indicated that distance from road is more effective than other parameters on deforestation in the study area. Because of irregular scattering of deforested area and low impact of other parameters, this model could not predicted deforested area, accurately.

This study was carried out to investigate poplar and paulownia’s growth under different spacing in a 5-year plantation located in Mazandaran wood and paper company’s fields in Sari-Iran. The trees were planted in three different spacing: 3×3m, 4×4m, and 5×5 m, each established in 3 replications. The quantitative parameters including DBH and Height were measured and a comparison was made between the stands height and diameter growth. Survival percentage was also calculated across the stands. The averages were statistically compared in a randomized block design in two forms: 1) two species were separately compared in their threefold spacing, and 2) two species were crossed in each spacing. Tukey’s test was used to compare the averages. Results showed a promising rate of survival over the stands. Moreover, the growth was significantly different amongst different spacing of the stands, representing the best growth in 3×3m spacing. In addition, the height of poplar was significantly more than those of paulownia, though the diameter growth assessment showed a reverse trend between the stands.

This study was carried out in Carpino-Fagetum orientalis, Rusco-Fagetum orientalis, Fagetum orientalis and Alno-Fagetum orientalis forest communities of Namkhaneh, Gorazbon and Chelir districts of Kheiroudkenar forests. The aim of the research was determination of the optimum number of ecological groups in the study area using indicator species analysis. Selective stratification sampling method was used to locate samples. One plot was laid out on each aspect and on each community. Totally, 120 samples were selected in the Fagus orientalis communities in the study area. The plot size was 400m2 considering to minimal area method. At each sample, floristic list in separate strata (trees, shrubs and herbs) were recorded using Braun-Blanquet scales. Cluster analysis was used for classification of samples. In this method, Sorenson distance measure was applied to calculate the distance matrix and flexible beta method as a cluster linkage measure. Indicator species analysis accompanied with Monte Carlo test was used to choose the optimum number of the clusters. Results showed that if four clusters were selected in the vegetation classification of Fagus orientalis communities in the study area based on cluster analysis, the number of indicator species, which had significant indicator values, would be maximum. Therefore, four groups could be introduced as the optimum number of ecological groups of Fagus orientalis communities in the study area.

Sprout is one of the most important regeneration mechanisms in degraded oak forests. The main goal of this research was study of effects of different physiographical conditions on oak sprout-clumps structure. For this purpose a section of Baba-Kooseh Olia forest in Kermanshah province with an area of 430 ha was selected. Then 84 square sample plots with an area of 1600 m2 by systematic - random network and random starting point were established in the mentioned region. Some important quantitative parameters were measured in plots including maximum height, crown area, basal area and number of sprouts in oak sprout-clumps. 5 altitude classes, 3 slope classes, 4 aspect classes and 3 land form classes were considered too. Result showed that the main woody species was Quercus brantii and average number of sprouts in oak sprout clumps was 5.9. Results of analysis of variances (ANOVA) showed that there was a significant difference between oak sprout-clumps structure relation to altitude and slope changes. There was also a significant difference in sprout number with aspect. The maximum number of sprouts was observed in elevation range of 1600-1700 m.a.s.l., in slope percent range of 0-12%, eastern aspect and in valley land form.

The best time of seed collection of Tilia in nurseries is at the end of September and the first of October. In this study, the effect of collection time on seed germination was investigated. Seeds were collected at the first of September, end of September and end of October with three weeks intervals. Because of their hard pericarps, seeds of Linden exhibit double dormancy and thus require both scarification and stratification (moist-prechilling) because of their impermeable seed coat and dormant embryo, respectively. Since the effectiveness of hydrogen peroxide (H2O2), of Tilia seeds were already investigated, in this study the seeds were immersed in concentrated hydrogen peroxide 1% for 40 minute, including stratification in river sand for 7 month, approximately. Stratification continued until emergence of radical. Then the seed were removed and counted. Results showed that the best time of seed collection is the first of September when the pericarp is semi-hard.

The purpose of this study was to analyze socio – economic factors influencing on adoption of agroforestry among poplar farmers in northern part of Iran. This research is descriptive – correlation. The statistical population includes all poplar farmers (in Golestan, Mazandaran and Guilan provinces) in the agricultural year 2006 that included 546 poplar farmers. A sample of 175 poplar farmers was selected, with Cochran formula, using "stratified random proportional sampling" method. A questionnaire was used to collect information. Content validity was achieved by a panel of experts in the fields of forest and natural resources extension. Questionnaire reliability was established by calculating Cronbach Alfa coefficient for dependent variable "extent of adoption of agroforestry among poplar farmers" which has been 0.91. The analysis of data has been carried out by using of descriptive and deductive statistics. The findings of research revealed that there are significant and positive relationships among adoption level of agroforestry independent variables consisting: literacy level, level of annual income, level of awareness about agroforestry, level of access to needful inputs, level of access to credit facilities and contact with extension agents. Significant difference was found in the mean score for level of adoption agroforestry in relation to using of credit facilities. The result of regression analysis indicated that 49.8% of the variations in level of adoption agroforestry were explained by level of awareness about agroforestry, level of access to credit facilities and level of annual income.

The aim of this research was to detect tree cover changes through Artificial Neural Network classification and post-classification comparison methods using landsat TM and ETM+ images in Golestan province, north of Iran with area of 20437.74 ha. Land uses and land covers were distinguished on the color composite image of the area and used as training sites for image classification that included all six bands of the imagery. We also used unsupervised classification to derive 100 clusters for purifying initial training sites. A post-classification comparison method was conducted on classified images of the years 1987 and 2001 and forest increase and decrease areas were identified. Accuracy assessment was implemented through test set pixels that were randomized and set aside from the training set pixels. We also used a LISS III imagery to assess the accuracy of the classification. Both methods proved the classifications and change detection in high accuracy.