Iranian Journal of Forest and Poplar Research
Year:2008 | Volume:15 | Issue:4 (30)|Papers Count:13

Depletion of natural forest due to different reasons has made the forest plantation important for extending forest area and wood production. Therefore, evaluation of forest plantation can play an important role to establish the plantation for the future. The objective of this study is to evaluate three different reforestation which was planted by Acer velutinum, Alnus subcordata and Fraxinus excelsior species. Each planted area with 49 ha was established in 1985. For data collection, 90 plots of 400 m2 were selected randomly. Different variable such as diameter, total height, trunk length, forked tree and number of trees in different classes of diameter were assessed. The obtained results indicated that Alnus subcordata with 3.2 percent in 5 cm diameter class and 38.5 percent in 20 cm diameter class had the highest values in survival, while Fraxinus excelsior with 31.7 percent in 5 cm diameter class and 19.7 percent in 20 cm. diameter class had the lowest values in survival. Data analysis for stem quality showed that Fraxinus excelsior with 31.6 percent forked trees had the lowest value, while Alnlls subcordata with 18.5 percent forked trees had the highest value in stem quality. Therefore, assuring seed quality for seedling production and protection after out planting could be resulted as a good quality of plantation.

The development stages in the natural forests run very slowly, which are not easy to recognize them within a short period of time. The duration of development of a stand and transition from one stage to another varies among the forest communities. Also the growth characteristics and dynamic of the stands varies in different development stages. This paper aimed to study the diameter and height increment of oriental beech in relation to tree age within the stages. For this purpose, four beech trees in diameter from 15 to 70 cm, were selected and stem analysis were carried out in an interval of 1.4 m logs. The results showed that the diameter increment has no uniform pattern and varies with the age of tree and the development stage of the stand. The diameter and height increment of young beechs are very slow at the early stage of growth (up to the age of 30), which starts to increase later. A beech tree with a diameter of 12 cm could be 30 years old and could reach to a height of 12 m. While, another beech tree with a diameter of 40 cm could be 140 to 150 years old and the total height of such tree could reach to 25 m. The development (successional) cycle of oriental beech in the Caspian region, which occurs with establishing of seedlings within the gaps after falling of old trees and continues up to physiological death of trees, is estimated between 200 and 230 years. At this age the diameter of tree could reach to 70 cm.

This investigation was carried out in spilt plot design with three replication and two treatments (depth of planting and seed density) in Pasand research station in North of Iran, Mazandaran province. Depth of planting performed in 4 levels including I, 1.5,2.5 and 3.5 cm and seed density including 40, 60, 80, 100 and 120 gr/m2. Germination duration, seedling collar diameter and height were recorded in year 3 after seed planting. Results showed that depth of planting has significant effect on germination duration and seedling survival. Seed density has significant effect only on seedling height growth. Seedling survival decreased with increasing of the depth of planting. Height growth of seedlings increased with increasing of the seed density. One can conclude that the best result could be obtained by planting of Cedrus seed in 1.5 cm depth with 80 to 100gr/m2 seed density.

Simmondsia chinensis (Link) Schneider) commonly known as jojoba (hohoba), is a dioicious evergreen shrub native to dry regions of south west of United States of America and north of Mexico. This species is very tolerant to drought and heat and is of great importance with regard to soil conservation and combat desertification. Moreover, it produces seeds which contain about 50% liquid wax, a unique substance which is of great value in cosmetics, food, pharmaceuticals and in other industries. To study the performance and adaptation of this species at south of Fars province in rain-fed and irrigated conditions, 286 and 225 seedlings were planted in statistical designs in 1993 and 1994 in Jahrom and Larestan, respectively. Growth, mortality and phenological factors including flowering, sex differentiation etc., of the plants were monitored at several irrigation levels. In Jahrom experiment, supplementary irrigation for two rows of plants continued after four years of establishment while the rest of the plants were left rainfed.In Larestan experiment, four different irrigation regimes (control, 45, 30, 15 day intervals) were applied during the trial period. Jojoba clearly demonstrated the potential and ability to adapt to the climatic and edaphic conditions in Jahrom region. For the first time in Iran, seed production was materialized in this experiment. The mean weight of produced seed/plant from the total 120 female plants in Jahrom in 1998, 1999 and 2000 was 15,22, and 35 Kg, respectively. Continuation of supplementary irrigation after the fourth year of establishment significantly increased height and crown diameter as well as seed production. The survival of rain-fed plants and the growth and yield in almost all treatments in Larestan experiment were not as satisfactory as they were in Jahrom due to several factors such as different provenance, heavy textured soil, and protection difficulties. However, jojoba generally demonstrated an acceptable adaptation in terms of reaching the stage of seed production. It is too early to recommend any commercial plantations unless more extensive experiments in the context of comparison of provenances and clones in different edaphic and climatic conditions are carried out.

This research was conducted in Boldaji research nursery from Chaharmahal and Bakhtiari province. At the first step, saplings of 39 clones from Alborz research nursery and 9 native clones were selected and planted on Boldaji research nursery in 1996. From these clones, 34 clones including 18 clones of populus nigra, 11 clones of populus x euramericana and 5 clones of populus deltoides were established. After cutting the poplars from first and second year's nursery, three nurseries with 1/1, 1/2 and 2/3 age (right number: root age and left number: stem age) were created. Some factors such as germination percent, resistance to pest and disease, frost tolerance, height and diameter in 0.5 meter height were measured. The results showed that Populus nigra clones have most germination percent. Height and diameter growth of populus euramericana 561.41 clone was more than other clones.

The process of natural regeneration including establishment of seedling under dead and mother trees ensure sustainable productivity in the forests. Qualifying the impact of dead trees on the density of establishment seedling in closed and open canopy in a mixed beech forest was studied. According to the field inspection, compartments 112 and 214 in Kheiroudkenar forests were chosen for sampling. Dead trees were considered as the center of sampling plot with different radius. Also in a 20-30 meter distance from dead trees, sound mother trees of same species were chosen. At the center of each plot, seedlings were counted in a circular sample plots with diffident radius. The results show that number of beech seedlings is higher than that of hornbeam and there is significant difference between establishments of seedling between dead and sound trees in an open canopy. Seealing density in open stand is higher than that under mother trees. Frequency of seedling around the dead trees was maximum. The higher decay class, the higher is the establishment of seedling. Also the number of seedlings is higher in small sample plots (100m2) which are closer to the dead trees. The results showed that the maintenance of dead trees is important and effective in establishment of natural regeneration in mixed beech forest.

Managers of logging operation are faced with profit reduction due to rapid increases in equipment costs, rapid depreciation of equipment and changing logging systems from harvesting the large trees to the smaller ones. The simplest way to confront this problem is improving the efficiency of the logging operation. Using work study methods, the required information for this purpose can be obtained. The aim of this study was to develop skidding time estimation model, skidding unit cost and productivity estimation of Timberjack- 450C skidder in two skidding directions and under combined logging system (tree length, long wood and short wood systems depending on different situations). The results show that skidder productivity rate in uphill skidding is 16.31 m3/hr and greater than its productivity in downhill skidding (12.32 m3/hr). Changing of logging system (using combined system (with 14.31 m3/hr productivity rate) rather than short wood system (8.88 m3/hr) gives rise to the increase of productivity rate. The Timberjack- 450C production cost which was working under contract was 145000 rials/ m3.

With covering an area of 14 ha, the investigated site is located in Armardeh Oak forests of Baneh city, Kurdistan province. The main problem of these forests is the lack of regeneration. In this research four different techniques of restoration operations, all of them in the shape of a participatory management approach were tested as randomized complete Design (RCD) with 5 treatment and 30 replications. The techniques are as follows: fencing outside the crown coverage, fencing beneath the crown coverage, fencing along with direct seeding and fencing plus seeding via Jiffy pellet technique. For the quantitative and qualitative measurements, thirty permanent macro plots each 1000 m2, were laid out in the study area randomly. Five microplots, each 1m2, were laid out within the macro plots for the restoration techniques.Inputs of the test were the number of primer seeds and outputs were number of seedlings and their heights. The results showed that only 2% of shed seeds have been converted to seedlings by late spring. Using fencing, even out of crown cover, caused increasing in natural regeneration up to one seedling per m2, Therefore, it seems that the main limiting factor of regeneration is livestock grazing. If fencing exerts beneath crown cover, natural regeneration will increase up to 3.9 seedlings per m2. Applying artificial methods increased regeneration significantly. Conservation with seeding via Jiffy pellet technique showed to be the best technical method either from number of seedlings or their heights point of view.

Considering the morphological characteristics of trees and the structure of stands, different development stages could be recognized in natural untouched forests. The development stages as well as the dynamic of the stands are basic references for application and development of nature based silvicultural interventions. The aim of this research was to study the structure, qualitative and quantitative characteristics of the main development stages (initial, optimal and decay) in two different plant communities of oriental beech forests, in the Caspian region. For this purpose two communities of Rusco- Fagetum and Carpineto-Fagetum in the experimental forest of Tehran University (Kheyroudkenar- Noshahr) were selected. In each community three sample plots, each one ha, were established and tree spieces, diameter and height of all trees were assessed. Moreover, one transect (10.100) was selected in each sample plot and the structure (vertical and horizontal profile) of the stand was studied. Results showed that all three stages could be recognized in the pure beech community, while the optimal stage has not been occurred yet in the mixed beech-hornbeam community. Distribution of stem number, basal area and volume in different diameter and height classes of all development stages are given in this paper.

Yasuj forests are regarded as the representative of south Zagros forests that are especially important due to density and species diversity. Two major species of these forests are Quercus brantii and Pistacia mutica. In this research leaf biomass and leaf area index (LAI) were assessed by the measurement of various parts of trees and finding correlation between different variables. In order to perform this research, a number of trees were selected by systematic randomized method and different variables such as diameter at breast, height, height of tree crown and small and large diameters of tree crown were measured. Also the leaves of a sector of the tree crown were picked off and after weighting, their dry weight were measured in laboratory. Gravimetric method was applied for calculating LAI in which the relationship between leaf area and its dry weight is used to estimate the total area of whole trees leaves. Mean Tree Method was used to generalize the result to the whole forest. The results showed that the amount of leaf biomass for Quercus brantii and Pistacia mutica were 1317.3 and 57.2 (kg/ha), respectively. For rapid estimation of this index allometric equations were suggested. Mean LAI in studied site was estimated to be about 1.2. Also analysis tests were done for more evaluation of the amount of elements in leaves.