Iranian journal of Forest
Year:2012 | Volume:4 | Issue:3|Papers Count:13

The development and deployment of harvesting systems aims to provide physically feasible, environmentally sound and economic solutions. The data of residual stand damage was collected from a mixed broadleaved stand in Kheyrud forest following the cut-to-length harvesting system using Timberjack rubber-tired skidder. After finishing the harvesting operations, damage to the bole, roots, extent of the damage, scars patterns, size and distribution was evaluated for all trees using stratified systematic sampling with a random start and fixed area plots. Results showed that scars occurred on 16.4% of the remaining trees, but the severity of scars varied significantly by species. Forty-six percent of scars for all species was considered as small size (>500cm2). The greatest average amount of damage to the bole occurred along the first 1 m up from the ground (93%) and also within 3 m of the skid trail centerline (86.4%). Gouges were present on 79% of all scars. The stratification of the study unit would effectively improve the accuracy of stand damage surveys.

Govater Creek is one of the creeks in Govater Bay at the end of east southern of Sistan and Baluchestan Province. Mangrove’s communities in this bay only consist of grey mangrove (Avicennia marina). In order to study the changes of mangrove vegetation area and density in Govater Creek from 1957 to 2006 (for 49 years) aerial photos with scales of 1:55000 and 1:20000 in 1957 and 1966, Corona satellite image in 1965, Landsat satellite image TM/ETM related to 1998 and 2001, IRS satellite image in 2006 and QuickBird satellite image in 2006 were used. Results showed that the changes rate of mangrove’s forest for this period has not been uniform but changes have been positive and area was changed from 101.19 to 149.18 ha. This change has average growing rate of 0.98 ha per year. The most of changes is related to years between 1966 until 1998. Generally we can conclude that before 1966, decreases have been in both density class (i.e. dense and sparse) and from 1966 to 1998, increases is observed specially in low density class and then until 2006 trend of changes has been slow and negative.

Habitat needs and requirement of important species in terms of distribution is necessary for natural resources management. Amygdalus scoparia is one of the important forest species in Markazi province for food, industries and environmental protection in different climatic conditions. The effect of physiographic factors such as land form, aspect, altitude, slope and some physical and chemical soil properties on qualitative and quantitative characteristics as height, crown diameter, canopy cover, tree density, regeneration and vitality percent was studied and then the data were analyzed using SPSS and PC-ORD (PCA method). The results of this study showed: 1- maximum height and crown diameter was observed in northern and eastern aspects. 2- The maximum canopy cover and regeneration was seen in northern aspect, valleys and in altitudes 1000- 1500 meters. 3- The maximum tree number was observed in southern aspect, amplitude and valley land forms, in altitudes of 1000-1500 and 1500-2000 meters and in slops of 0-20 and 20-35%. 4- The maximum vitality percent was observed in northern and southern aspects, slope and valley land forms, in altitudes of 1000-1500 meter and in slops of 0-20%. The factors of height, crown diameter, canopy cover, tree number, regeneration and vitality were scattered in the positive direction of first axis by Principal Component Analysis (PCA) that had the highest correlation with sand.

The main purpose of this study was to determine the best treatment for Colutea persica seeds to break their dormancy and better regeneration. Applied treatment Includes: soaking seeds in Sulfuric Acid solution (98%) for half an hour, scratching treatment, two and four weeks cooling, using Gibberellic Acid and cooling treatment simultaneously for two weeks and finally using distilled water as reference control. Statistical analysis was conducted randomly by using five replicates (with 10 seed samples in each one) in Lab conditions. Number of germinated seeds was evaluated in different treatments. The data were analyzed using Duncan’s test at level of 5% probability by SPSS software package. Results demonstrated that the highest germination percentage (Gp) and Germination rate (Gr) was found in seeds for which scratching treatment was applied (88% and 8%, respectively). In addition, the results revealed that hindrance in budding process occurs due to the impermeability of the seed coat. Moreover, no dormancy in embryo was observed in this species.

Fandoghlou forest is one of the most important recreational areas at regional and national levels, thus present study was aimed at determining the amount and intensity of damage to residual shrubs due to recreational activities in this forest. For this purpose, a part of forest that was as a forest park and affected by recreational activities was selected. Using a grid of 50*50 meter, a number of 86 circular plots with the radius of 5m were selected in the region. The results showed that about 56% of plots were moderately and heavily damaged. In order to determine the most affected variable, three variables were selected and analyzed using factor analysis. The results of factor analysis showed that scar length extended around 71% of total variations of primary variables, alone. On the other hand, the results of one-way ANOVA and Tukey test showed that regarding to the amount of damage to shrubs, scar length and scar area, there is a significant difference among different categories of plots (p value=0.000). The results also showed that there is a exponential relationship between the number of damaged shrubs and distance from the forest edge. Thus, it is concluded that recreational activities cause high damages to forest, hence rational planning and management should be conducted for reducing these damages.

Nowadays, with mechanization development, evaluation of machine productivity and calculation of average cost of skidding for each hour and each cubic meter is necessary to compare their efficiency. In this study, the mathematical model of production and cost of steel tracked skidder LTT-100A was studied in Tarbiat Modares University Experimental Forest (TMUF). Continuous time study was applied during skidding operation to record the time spent for each component of skidding. The obtained data was then analyzed using multivariable regression analysis to build the mathematical model of production. Results showed that skidding distance, skid trail slope and volume of logs at each cycle are significant variables influencing skidding time. The share of delay was 14.94 % of total time while 44% of delays time was identified as technical delay (unavoidable delay), personal and operational delay were recorded 33% and 21% percent, respectively. Skidder productivity regardless of delay time and effective time were calculated 5.84 m3/h and 4.98 m3/h, respectively. Total average cost of system was estimated 265678 RLS/h and 54330 RLS/m3, respectively (Rials= 50cent).

The primary purpose of this study was to evaluate the effectiveness of extension and educations programs in natural management and related factors. To do so, information on extension and educations programs and criminal records related to natural resources were gathered from 17 villages in Ardal and Kiar counties in a time period of 2004-2010. Soico-economic information was also recorded in a field survey using a proposed questionnaire in order to gather this information from 20 local people whom were randomly selected in each village. Local people who were participated in extension and educations programs also with illegal activities recorded before extension and educations programs were divided into groups of 1- those with recorded illegal activities related to natural resources after passing these programs and 2- those without them after passing these programs. Afterwards, a Wilcoxon test was used so as to reveal any significant difference in the number of illegal activities before and after extension and educations programs. In order to investigate soico-econmoic effects on effectiveness of extension and educations programs, at first, the villages were clustered based on soico-econmoic characteristics. Finally, chi-square test was used to evaluate the relationship between extracted clusters and the numbers of recorded illegal activities in each cluster.The results showed that there is a significant difference in the numbers of recorded illegal activities before and after the extension and educations programs. The numbers of recorded illegal activities significantly reduced after passing extension and educations programs. However, reducing in the numbers of illegal activities was not the same in every condition, and individual and socio-economic factors. Facilities and services provided by government had significant effects on success in extension and educations programs. The results indicate that socio-economic factors should be considered when designing and performing extension and educations programs.

Street trees are one of the most important components of urban green spaces. Any defects in street trees may cause injuries to human, vehicles and buildings. In this research, the assessment of hazardous oriental plane (Platanus orientalis L.) trees was carried out on both sides of Valiasr Street (between Tajrish square to Tous street cross section). Eight types of tree defects were detected: dead woods, cracks or seams, weak branch unions, decay, wound or cankers, root problems, poor tree structure and contact with power transmission lines. Totally, 457 trees were sampled. The results showed that the dead woods and poor tree structure are the main tree defects (with values of 80 and 69 percent of all sample trees, respectively), while weak branch unions and decay have less importance. Regarding to combination of tree defects, 19 trees were classified as very dangerous and must be removed. Furthermore, trees in medium and high risk classes were classified based on their potential to move toward more dangerous classes. Totally, improvement practices such as pruning of dead branches of trees with medium and high risk and cutting of very dangerous trees are recommended.

The purpose of this research was to compare the development stages in the managed and unmanaged forests, and the resultant changes on the biodiversity of understory vegetation. This study has been conducted in the beech communities of Ramsar region located in the north are forests of Iran. In order to determine the biodiversity of different development stages, the patterns of development stages (initial, optimal and graded) for each of the understudy zones were determined in two 10ha zones of the beech forests in the north of Iran. In order to study the understory species, 112 releves in an area of 100-m2 were done and the percentage of understory species frequency was recorded using Braun-Blanquet Method. Three development stages of initial, optimal, and degraded were observed in both zones, which the highest frequency of polygons in the managed zone are in the initial phase while those in the unmanaged zone were in the degraded phase. The results from the survey on the biodiversity in the phases of the zones showed that in both managed and unmanaged zones, the maximum and minimum richness of Margalef are in initial and optimal stages, respectively. The indices of biodiversity in both managed and unmanaged zones (regardless the phases) revealed that there are no significant differences between the biodiversity of understory species in these two zones.