مجله جنگل ایران
سال سوم شماره 3 (پاییز 1390)

Oriental Beech forests have economic and ecological important roles in northern forests of Iran. Therefore qualitative and quantitative controls of their stands are essential in management of these forests. This study is aimed at determining the stem taper, form factor, and slenderness coefficient of Beech species in four growth stages; (small pole, pole, saw-timber, mature) in natural forests of Lomir area located in Asalem, Guilan Province, Iran. In this study, 159 Beech trees were selected and analyzed based on diameter classes (5 cm). Analysis of Variance and Tukey test showed the factors of stem taper and tree natural form were significantly different at small pole stage compared to other stages (p < 0. 05). Beech species had the highest value of stem reduction factor and the lowest value of tree artificial form factor in stages of small pole (the class with a diameter 10 to 30 centimeter) and mature (the class with a diameter over 80 centimeter). These results indicate that Beech form is affected by growth stages in natural forests. So, the separate management and cultivation planning during various growth stages is necessary in order to obtain the maximum benefit of the Beech natural stands.

Evaluating the cost of different harvesting alternatives is necessary to develop an efficient forest operation plan. This requires estimation of harvesting production rates, equipment and labor costs. To do this, the harvest planner must understand the operating and cost characteristics of the available logging systems especially considering the tree size, skidding distance, and skidding direction. Productivity studies are still frequently used to describe, understand and improve forest operations. This study was carried out in Namkhaneh district in Kheyrud forest using Timberjack 450c wheeled cable skidder. The objectives of this study were to formulate time-consumption models for short-log and long -log methods and determine factors such as production, cost per hour and machine rate during the skidding phase. The study used continuous time studies based on empirical data for two logging methods. The regression model for short-log method included the following factors: skidding distance and number of log. However, the model for long-log method included: skidding distance and winching distance. Results indicated that the productivity of the short-log and the long-log with delay times was found to be 6.71 and 9.84 m3/h, respectively. The productivity of the short-log and the long-log without delay times was found to be 8.92 and 13.34 m3/h, respectively. The cost in short-log method with and without delay times were 98120 and 73810 Rials/m3, and the cost in long-log method with and without delay times were 66910 and 49350 Rials/ 3, respectively. Productions in both short and long log methods were directly related to skidding distance. Also, productivity was more sensitive to skidding distance than number of log and winching distance. Finally, this paper analyzes the delay component of time-study data sets.

This research was carried out in parcel 15 of the first district of Arabdagh afforestation plan to study the growth performance of 17- year old Turkish pine (Pinus brutia Ten.) plantations (ca. 63 ha and 2×3 m spacing). Sixty three sample plots were selected as random-systematic design. Within each plots, DBH, Total Height (TH), form factor, natural regeneration, stem form, crown vitality, stem health, mode of branching,stem straightness and crown symmetry were recorded. Computation of Dominant Height (DH), mean height and DBH, Basal Area (BA), height/DBH ratio, Total Volume (TV) and Mean Annual Increment of Volume (MAIV) and analysis of variable correlations were performed. Results showed that Arabdagh plantation had greater DBH and BA (14 vs. 13.7 cm and 27/983 vs. 24 m2/ha respectively) and less DH, mean height, TVand MIAV than the good sites of Turkish pine plantations in the country of origin with same age and plantation density which generally located between good and medium site conditions for Turkish pine plantation. Therefore regions with same ecological conditions can be considered as suitable sites for Turkish pine plantation.

Arbuscular mycorrhizas fungi (AM) are the most important microorganisms of soil having an important role in soil fertility. The symbiosis rate between AM and plants are different based on specific physiological characteristics and morphological root characteristics. Thirty individuals of Acer cinerascens grown in natural habitats located at Bazoft, Chaharmahal-o-Bakhtiari, the western forests of Iran, were chosen. Roots were sampled during spring and autumn to find out the interactions between arbuscular mycorrhizal and soil elements. Arbuscular mycorrhizal fungi were isolated and characterized by wet sieve. Then roots were stained and colonization percentage was measured. Four species of Glomus and one species of Acaulospora were identified. Significant difference was found between arbuscular mycorrhizal colonization percentage and spore frequency in spring and autumn. Significant correlation was observed between colonization percentage and availability of potassium in spring.

In order to investigate the effect of tree forms on characteristics of Quercus brantii, seeds of 60 trees (both tree forms: high and coppice trees) were collected and studied on north-facing slopes ranging from 1040 to 1960 m a.s.l in Gilane Gharb city, Iran. The results of analysis of variance showed that there is significant difference between two forms of trees regarding to number and weight of seed, unsound seed, canopy and height of trees. Analysis of correlation indicated that in high trees, 1000- seed weights had positive and significant correlation with number of seeds, weight of individual seeds, sound seeds, unsound seeds (p≤%1), and with germination (p ≤%5). In coppice trees, 1000-seed weights had positive and significant correlation with individual seed weight, sound seeds(p ≤%1), and unsound seed(p ≤%5), but they had no correlation with seed number and seed germination. The results of ANOVA showed that the difference between two forms was significant other than individual seed weights and 1000-seed weights. Therefore it would be better to collect seeds from high trees, use the seeds of trees grown in the same elevation (considering other affecting conditions) and from different areas to prepare seeds for seedlings and afforestation.

Valuation of environmental resources plays an important role in environmental economics in recent years. Qaem eco-park is one of the most important recreation areas in Kerman province. Estimation of recreational value of the park, using contingent valuation method is the purpose of this study. To achieve this goal and estimation of people’s willingness to pay, Logit model based on maximum likelihood method was used. Data for this study have been collected by 115 questionnaires. The results showed that the average of WTP for person to visit the park is 2157 Rials and households’ WTP is 178,191.33 Rials. According to the results, one percent increase in the bid price decreases the probability of its acceptation by 40.5 percent. Also, the results show that variable of income has the most effectiveness on acceptation of bid prices.

This study was carried out to identify the best required time for stratification along with the optimum time and generation power test of seeds. The treatments include 22 different periods of stratification from 10 to 32 days. The experiment was done as completely random design blocks with four replicate with 30 seeds within each block. The Ending time of stratification period was the same for all treatments. The percentage of rotten seeds, seed germination and rootlet length were measured, and then the obtained data were analyzed statistically. The results indicated that Chilgoza seeds incubated in temperature of 4°C for 33 days could germinate 38%. While the seeds with less than 16 days has no germination power. In general, this study suggests the period of 23-30 days as the best time for stratifying Chilgoza seeds.

Measurements of gross rainfall (GR), throughfall (TF), and stemflow (SF) were conducted inside oriental beech (Fagus orientalis Lipsky) and oak (Quercus castaneifolia C.A.M.) forests in Kheyrud Forest Station of University of Tehran. GR was collected by means of three manual collectors placed in neighboring open areas from the study plots. TF was collected by thirty five TF manual collectors positioned randomly underneath the trees canopies. SF was collected from beech and oak trees, with different diameters by thespiral-type SF collection collars installed at diameter at breast height. Rainfall interception (I) was calculated indirectly as the difference between GR and sum of the TF and SF. The cumulative GR depths of 13 and 14 events for oak and beech forests were 297 and 270 mm, respectively. On the event scale average ratios of TF:GR, SF:GR, and I:GR in the oak forest were 75.50%, 0.26%, and 24.24%, respectively, whilst those of the beech forest were 71.30%, 2.70%, and 26%. Strong positive correlations were observed between TF and GR in both oak and beech forests. Results showed fairly strong negative relationships between I:GR and GR in both forests. Rainfall interception contributes a notable amount of incident rainfall in the oak and beech forests and its measurement, therefore, is an essential element while assessing water balance on the catchment scale.