Iranian journal of Forest
Year:2018 | Volume:10 | Issue:2 |Papers Count:15

Urban pollution can damage animals and plants. Leaf is one of the most sensitive organs to air pollution, which can be changed morphologically and physiologically under pollution stress. The present study was conducted to evaluate the accumulation of heavy metals in Platanus orientalis and Pinus eldarica leaves and also their morphological (leaf area, leaf moisture and specific leaf area) and physiological (malondialdehid, proline and catalase) responses in the polluted (Center of Tehran) and non-polluted area (Chitgar Forest Park). For this purpose, 20 healthy tress (10 trees of polluted area and 10 tress of non-polluted area) with same age, height and DBH were selected. The results showed the concentration of lead, cadmium, and chromium in the urban area was higher than those obtained in non-polluted area for Platanus orientalis and Pinus eldarica. Zinc concentration in Platanus orientalis leaves of polluted area was less than that in non-polluted area, while there was not observed a significant difference between these areas for Zn in Pinus eldarica needles. Leaf moisture of Platanus orientalis in polluted area was less than that in non-polluted area, but there was not found a significant difference for leaf area and specific leaf area. Proline and catalase activity in polluted area were more than those in non-polluted area for both Platanus orientalis and Pinus eldarica, whereas malondialdehid in polluted area was more in respect to non-polluted area only for Platanus orientalis. There was found an increase for malondialdehid in Platanus orientalis leaves in polluted area compared to non-polluted area, but this value was not significant for Pinus eldarica. According to the findings, it can be said that Pinus eldarica is relatively more tolerate in respect to Platanus orientalis, but Platanus orientalis is more stronger in accumulating pollutants, which is the main reason of large variations of Platanus orientalis compared to Pinus eldarica.

Forest roads are constructed to facilitate forest protection, reforestation, logging operations and maximizing the value of forest products. Therefore forest roads are key infrastructures in the development of the region. This study aims to plan forest road network using artificial neural network and GIS regarding forest road technical principles. First the criteria were chosen using Delphi method and then they were weighted regarding their importance in road planning. After that the criteria were combined with corresponding weighs to achieve suitability map based on the degree of suitability for road allocation. Value and coordinates of each pixel were extracted by ENVI software and were normalized in the range of 0-1 for modeling by MATLAB software. In this study two neural networks were used for modeling, including multilayer perceptron (MLP) and radial-bases functions (RBF). The neural networks estimated suitability of different pixels in other districts based on the Patom district results. Using an ArcView GIS extension, PEGGER, two forest road networks were planned. The results showed that MLP provides better ability for estimating suitability of pixels for road passage in comparison with RBF with the R2 of 0. 994. A linear regression was also used to compare the results of the proposed neural networks. The results revealed that neural network improves the results in comparison with the linear regression and results showed that the second road alternative was optimum network with regard to the unit cost.

In order to consider oleo-gum resin extraction periodicity on biometric variables of wild pistachio (Pistacia atlantica subsp. kurdica), three different forest areas in Kurdistan province, west of Iran, were selected based on difference extraction periodicities (regular, irregular and without periodicity). Then homogenous unit maps in GIS environment produced, and one unit with identical characteristic from any three different areas were selected. Sampling in the selected units was implemented on 100 randomized pistachio tress with diameter at breast height (DBH) more than 25 cm. On each tree, DBH, total height, crown diameter and number of fruit bunches were recorded. Then the measured trees were classified to three different diameter classes as: 25-35 cm, 35-45 cm and more than 45 cm diameter at breast height. Comparison between averages of the interested variables was done using ANOVA and Duncan tests. Results showed that except to the average of number of clusters, the averages of other interested variables, at least in one diameter classes, were significantly higher in the area with regular extraction periodicity compare to the area with irregular extraction periodicity. Finally, we concluded that oleo-gum resin extraction without regular periodicity had a negative impact on biometric variables of wild pistachio, therefore, we propose to consider the periodicity in the future extraction.

The oak mortality in the west of Iran has been studied in various aspects. However, the physiological mechanisms underlying susceptibility or resistance of tree to mortality are poorly understood. To find out whether the features of xylem, such as tree ring-width, size, and the number of vessels affect the susceptibility to disease, these features were compared between healthy and dead trees in Dalab forest of Ilam province. By cross-dating the time series of the ring widths, it was determined that the most of the dried trees dies in 2008. However, data analysis showed that the symptoms of the disease appear in xylem, several years before the dying. Since the early 1990s, the trend of annual variation in the vascular features of dead trees were different compared with the healthy ones, and at the same time, the ring width of these trees has decreased. Successive shrinking of earlywood vessels and narrowing ring width reduces the tree's hydraulic conductivity. However, during this decade, dead trees actively tried to cope with reduction by increasing the number of their vessels (the incubation period of disease). Nonetheless, from the early 2000s till the death of sick trees, trees were not able to produce more vessels (the emergence period of disease). Overall, it can be concluded that oaks with smaller vessels are more susceptible to drying, and after infection, the decrease in diameter growth and successive shrinking of earlywood vessels aggravate the tree's condition leading to its death.

Logging operation by skidders can lead to soil compaction, rutting and erosion of skid trails. Therefore, in order to restore the soil physical properties of skid trails, it is necessary to perform improvement treatments. In this study, four compaction improvement treatments were investigated on one-year-old skid trails with two slope classes of low slope (0-20) and high slope (over 20) and 5 replications. 360 soil samples were taken, half of them before applying the treatments and the other half a year after the treatments application, and were analyzed to evaluate the improvement effect of the treatments. Results of low slope class showed that there was a significant difference between soil bulk density and porosity percentage in improvement treatment plots and control plots of forested area. Treatments of orthogonal groove, diagonal groove and logging residuals showed no significant difference with the control skid trail, and only the use of the combined treatment was able to significantly reduce bulk density and increase porosity percentage compared to the control skid trail. For high slope class, all soil improvement treatments showed a significant difference with control plots; however, compared to the control skid trail, none of the mentioned treatments could cause significant differences. Among the studied treatments, the combined treatment had the best performance in restoring soil physical properties in both low and high slope classes.

The dead trees, as a soil forming factors and dynamic of forest ecosystems, is regarded an important role in improving fertility. They also effect on biodiversity, regeneration of forest, increasing of forest soil nutrient and soil nutrient cycling. For this study, soil around the dead Populus caspica trees was examined in an area of 382. 5 hectare in the Safrabasteh forests of Guilan province. In this study strip transects with 10 meter-wide were used and all of their dead Populus caspica were considered. With respect to the amount of decay, every dead Populus caspica tree was classified into four groups called new dead tree, decay beginning, advanced decay and full decay. Beside each dead tree, three soil samples were collected from the depth of 0-20 cm and were sent to the laboratory for analyzing. In this study, the chemical characteristics of soil included Organic carbon, Nitrogen, Phosphorus, Potassium, EC, C/N and pH were analyzed. The results obtained from this study indicated that there is significant difference in some soil chemical properties at the confidence level of %95 between the different degrees of decay. The highest amounts of soil chemical properties were under advanced and full decay. Based on the results, it can be declared that soil chemical characteristics in different degrees and distances differ can be changed.

This research carried out to quantification of juniper stands structure in Kandragak region. For this purpose, three one-hectare study area were selected and the full calipering and the nearest neighbor’ s methods were used to quantification of stand structure. Some indices including mingling index, distance to nearest neighbors, Clarke and Evans, and uniform angle and dimensional differences were employed to quantification of the stand structure. Results indicated the mean of DBH and crown coverage were 13. 2 cm and 8. 7 m2, respectively. Results showed mean value of Clarke and Evans and uniform angle indices was 1. 05 and 0. 45, respectively that revealed clumped or random distribution of juniper trees. The mean of mingling index calculated 0. 14 among three study area showed low tendency of juniper to mix with other tree species. The mean value of distance to the neighbors was 3. 70 meter and the height and diameter differentiation were 0. 16 and 0. 23, respectively. According to findings juniper in the natural habitats tends to be fairly pure in species composition and have slightly heterogeneous diameter distributions and uniform tree height. Accordingly, in the decision making and planning strategies, maintaining the natural structure and spatial pattern of trees have to be sufficiently considered.

Trees respond to environmental and climatic changes during their biological life. Tree rings study is one way to discover these responses called dendrochronology. The most effective climatic factors which affect tree rings are temperature and precipitation. Present study aimed at investigating the influence of temperature and precipitation on annual growth of oriental beach (Fagus orientalis Lipsky) and oak (Querscus castaneifolia C. A. Mey), which clearly illustrate climatic factors on their tree rings. Trees were selected in three altitudes (450, 900 and 1380 a. s. l), from forest part 2 of Neka and Haft Khal in central Alborz mountains of Iran. Core samples were extracted from two sides of trees with an increment borer. Growth rings widths were measured by using LINTAB6 table with accuracy of 0. 1 mm. The measurement results were analyzed using time series analysis software TSAPWin. Results showed that growth pattern of oak and beech in three altitudes were not similar. Altitudes affect mean growth of these species significantly. In each altitude, oak and beech have shown different responses to temperature and annual precipitation. These differences could be depending on species’ nature. In response to climatic factors, oak was more sensitive than beech. In high altitude, previous growth season temperature of affect oak chronology negatively while had positive effect on mid and low altitudes. In all altitudes, oak positively affected by precipitation of June (of current growth year). Beech of high altitude showed positive correlation with March and summer precipitation. However, no significand correlation was detected in beech in low altitude.

This study was carried out to evaluate the effects of different irrigation levels on some morphophysiological properties of pine (Pinus eldarica Medw. ) in Tehran green areas in 2015 and 2016. For this purpose, water requirements of pine in the studied area was estimated using the method recommended by FAO for drip irrigation system and WUCOILSIII method, then the effects of four levels of irrigation (50, 75, 100 and 125% water requirements) on some growth properties of pine species during the growth season were investigated in a split plot experiment in time based on randomized complete block design. The results showed that the amount of rainfall in April (in the first year) and also in April and May (in the second year) were more than the estimated amount of pine water need. The highest amounts of water requirement in both years were estimated in June (204. 6 and 246. 45 liters per month), wherase the lowest ones in the first and second years (139. 5 and 117 liters per month) were determined in May and October, respectively. The treatment of 50% water requirement significantly decreased the branch length, branch diameter, height, tree crown diameter and pine crowns and increased the percentage of leaf and branch dry matters and proline in comparison with the control treatment. Leaf abundance per tree and leaf succulence were not affected by irrigation treatment. In general, the results of this study showed that meanwhile maintaining the important indics of green erea, water consumption for Tehran pine trees in the studied area could be reduced to 50% of the water requirement in the first months of growing season and to 75% of that in the others months of year.

Due to global climate change, climate change in Iran is inevitable and the results of the climate studies clearly show that the Hyrcanian climate has been warmer over the past 50 years. In this research, the current and future distribution of oriental beech (Fagus orientalis Lipsky) was studied using an ensemble method including five different species distribution models. We used five general circulation models under four existing reprehensive concentration pathway (RCPs) to project the impact of climate change on the distribution of oriental beech by 2070. In addition, the stable, gained and lost suitable habitat of oriental beech were determined using range size change analyses under climate change. The results indicated that the area of suitable habitats with high certainty would be decreased by 72. 79% and 89. 88% under RCP 2. 6 and RCP 8. 5, respectively, by 2070. The results of the range size analyses of oriental beech showed only 24. 84% of suitable habitat would remain in the most optimistic condition (RCP 2. 6) and stable the suitable habitat would decrease by 7. 13% under RCP 8. 5 by 2070. Also the lowest and highest rate of suitable habitats lost will be by 72. 79% and 89. 85% under RCP2. 6 and RCP 8. 5, respectively, by 2070. It is suggested that the climate change impacts should be considered in the management decisions and conservation plans related to the oriental beech in the Hyrcanian forests.