فصلنامه جنگل و فرآورده های چوب
سال شصت و ششم شماره 1 (بهار 1392)

Climate change is defined as long term and irreversible changes in the climatic behavior of a region. Many studies have been conducted in different regions of the world on climate change. The results of these studies show considerable changes in climatic factors especially in precipitation and temperature. In this research، the trend of changes in annual and seasonal rainfall and temperature in 24 synoptic stations over a 50-year data period (1956-2005) was investigated in Iran. The Mann- Kendall test and linear regression technique were used to analyze the trend of changes in climatic factors. The results showed both increasing and decreasing trends in annual rainfall at various regions of Iran. Annual rainfall in northern slopes of Alborz and western slopes of the Zagros Mountain as well as in eastern and southeast parts of Iran had a decreasing trend while in the central of Iran the trend of changes was increasing. In southern region of Iran the rainfall had an increasing trend. The results also showed that temperature in most of the studied stations over the considered period was increasing. The highest and lowest changes in temperature were seen in the mean temperature of summer and winter، respectively. Ahwaz and Khorramabad stations had a decreasing trend and over all seasons would go toward more cooling. The temperature trend in Oromiye was decreasing in autumn and summer while Shahrekord and Bandar abbas had the same trend in summer and winter.

Christ thorn (Ziziphus spina-christi) is a forest tree species that grows wild in the arid and semiarid areas of Asia and Africa where rural populations intensively use its fruits، leaves، bark، and wood. The death of a large number of seedlings with root rot symptoms has been observed since 2008 in Kazerunand Lamer nurseries in Fars Provience of Iran. Necrosis of internal skin and crown were also detected in the infected plants. Some isolates of Fusarium oxysporum were recovered through plating the infected tissues on the PDA medium which were found to be pathogenic on the Christ thorn seedlings through Kock’s postulate. Since Christ thornis cultivated in the arid areas and damping-off of the seedlings is a common disease in these areas، the present study was conducted to study the co-effects of water stress and the pathogen on the plant seedlings. The effects of F. oxysporum infection and the levels of irrigation frequencies (every 2، 3، 5 and 8 days) was studied through using a factorial experiment that was arranged in a randomized complete block design with four replications. Some morpho-physiological features of the seedlings such as height، leaf number، leaf height، and width were measured. The results of this experiment indicated that the growth response of Christ thorn to drought stress depends on the levels of irrigation applied. Compared to the unstressed control، the interaction of F. oxysporum and water stress reduced the seedling height and leaf numbers up to more than 50%.

Nowadays، the Zagros forests are being destroyed due to over pollarding and overgrazing of the trees. However، some less-disturbed and wild regions can be found in these forests that have not been destroyed due to being un-accessible or being a holy place. These regions can be used as a suitable standard for planning and managing the other forest areas. In this study، we investigated one of the indicator characteristics of the forest stands، i. e.، spatial patterns of trees، and determined the suitable plot size to study it. For this purpose، 3 one-hectare (100 m × 100 m) nested plots with areas of. 25،. 5، and. 75 of ha in less-disturbed stands were selected. Coordinates of all trees were determined using azimuth-distance method، and the spatial point pattern was analyzed through Ripleyls K- function for each nested plots، individually. The results showed that the spatial patterns of the trees in all nested plots، except for the. 25 ha، were clustered، and the minimum plot size to study the spatial patterns in such forest stands was. 5 hectare.

Mental models are the reference frame works in which people interpret the world around them. In this paper، mental models of two main stakeholder groups (forestry experts in Forest، Rangeland، and Watershed Organization and the local herders of Lire-Sar watershed) were analyzed in the context of forest degradation. The required data have been obtained through semi-structured interviews with individual members of each group. The results were conceptualized in the system dynamics approach and the cause and effect diagram of each groups were derived. The results of the mental models diagraming of the two groups show that each group blames the other group for the degradation process and they are not expected to revise their actions. Organizing training courses about the goals and objectives of the forestry projects for the local herders and villagers، and improving the forestry organization experts capacity and capability in dealing with the mental models that are based on the policies and decision makings، would be useful in creating a proper atmosphere for these two groups to understand the priorities and objectives of each other.

In the paper، the influence of duration of decking on increasing the length and width of end checks and the role of paraffin and anti-checking iron treatments in preventing these changes were investigated. The logs of tree species of Fagus Orientalis، Carpinus Betulus، and Alnus Subcordata that are of the most common species in the northern forest of Iran were chosen for present study. To carry out the sampling process، 75 logs of each species were selected which 25 logs were assigned to metal treatment، 25 logs to paraffin treatment، and 25 logs to control samples. Length and width of main checks on the cross section of logs then were measured in two levels with 20 days time intervals using caulis. The randomly design، Student›s T and Dunnett T3 tests were applied for mean comparisons at the level of 0. 05 percent error. The results showed that in the most cases، treatment S had positive effects on the quality of logs. Among three investigated species Fagus Orientalis was the most sensitive species and Carpinus Betulus was the most flexible one that positively reflected to the anti-checking iron. In addition، paraffin treatment had no significant effect on the dimensions of the checks on the studied species.

Studying and comparing the wood anatomy and fiber morphology of the Field Elm trees that grow in different sites، along with assisting us in the identification and grouping of the Ulmus spp. will help us understand the reaction of these species to different climatic factors. In this study، some wood anatomical characteristics and fiber morphology of Gorgan and Komijan native Field Elms (Ulmus carpinifolia Borkh.) were investigated. The results showed that although these trees exhibit some outlined features of Ulmus spp. they also have unique properties (i. e. delicate spiral thickening in the earlywood vessels of Komijan or fused rays in Gorgan samples) which have not been reported for these species so far. Moreover، the Komijan samples had pronounced narrower tree rings and tyloses in the vessels while this feature was almost absent in Gorgan samples. Some of these differences – especially vessel related features- were linked to the colder and drier climate of Komijan but in order to have a better understanding of the other observed dissimilarities، more studies need to be conducted.

The dendroclimatology science reconstructs the past climates through studying the relationship between climatic indices and tree rings which is a pre-requisite of agricultural and natural resources studies. Basically، the tree species of highland regions are more sensitive to the climatic conditions. Unfortunately، in the highland forest regions like Chaharbagh، Gorgan (case study) there is nometeorological station. In order to solve this problem، in this study various interpolation methods of temperature and precipitation data from the area understudy were compared and the best methods were determined. Then، through using the best interpolation methods، monthly temperature and precipitation variables in the period 1982-2006 were calculated in the tree ring sampling points for two tree species (i. e.، Juniperus polycarpus and Quercus macranthera). Finally the correlation between yearly tree rings and monthly temperature and precipitation، Standardized Drought Index (SPI)، and Reconnaissance Drought Index (RDI) were evaluated. The results show that among various interpolation methods the 3D linear gradient and linear and nonlinear hybrid methods are the best interpolation methods for temperature and precipitation، respectively. Correlation coefficient analyses showed that the effective meteorological factors on the growth of Quercus macranthera trees are the positive effect of the SPI of June and the negative effect of the March temperature. The July precipitation and the pre-growth September temperature have a negative effect on the growth of the Juniperus polycarpus trees.

Wood samples of upper Triassic–middle Jurassic were collected from eastern Alborz، Gheshlagh coalmines. These samples were collected from trunks and roots of the remaining standing trees and some scattered timbers. Thirteen samples were transferred to the lab and were investigated after being prepared in the form of thin layers and sections. All of the materials were identified as Gymnosperm-like woods of pycnoxylic tracheidoxyl Homoxylous type. These are kinds of fossil woods in which the woody cylinder is not dissected by the thick parenchymatous woodrays (so-called manoxylic woods). Almost in all samples (but one) the growth ring boundaries were not distinct and there was no resin canal. One can identify at least two genera، one of which was reported previously in Kerman. Based on the wood remnants and the leaves of the plants such as Scytophyllum، Equisetes، Ferns، Ginkgos، and also Coniferes، the age of Gheshlagh is assumed Triassic.

With regard to the importance of the conduction of limit resources to the superior industries، study on the country’s priorities in the industrial areas and products is essential. Considering the fact that Qom province has special conditions، this provincecan be consideredas a wood centerin the wood industry in which prioritizing the wood and paper industries is essential. To reach this goal two stepsare needed to be taken، the first step is to design a hierarchy based on five major groups of criteria which are financial & economical، infrastructure، material & product، technical & man force، and social & cultural. The weight of the indicators was established by Analytical Hierarchy Process. In the second step، based on the criteria weighing values، alternatives have been ranked through TOPSIS. The results showed that financial and economical criterion as a major group has the highest priority with. 28 weighing value and investment attraction as a sub criterion has a weighing value of. 11. Besides، the results of the alternatives ranking showed that the other types of wood furniture alternative gain the maximum priority and the printing، writing، and newspaper papers gains the minimum priority.

The recycled paper undergoes a decrease in qualitative features in spite of its advantages and potentials. This research was carried out in order for the optimum employment of old corrugated cartons in recycling paper and improving the quality of the recycled paper. Adding cationic starch to the recycled pulp causes the reduction of the lost bonding in the pulp. It accordingly increases the strength properties of the produced paper up to the quality level of the virgin pulp. Starches differ in their effects on the basis of their sources of extraction. In this study، the cationic starches of potatoes and wheat، each at four different levels (0%، 0. 5%. 1% and 1. 5% with 0. 4% alum) were used as the neutralizers of anionic trash. Hand sheets with a grammage of 120) g/m2) were made and their strength properties were measured. Moreover، the absorption rates of two kinds of starch on the pulp were calculated using the Acid-Phenol Method. The results indicated that the use of 1. 5% of potato starch and 1% of wheat starch had an optimum effect in increasing the strength of the produced paper. Concerning the comparison of these two types of starch، the potato starch was more effective that the wheat starch. The absorption diagram of these two kinds of starch also revealed that the potato starch showed a greater absorption and retention on the pulp.