فصلنامه تحقیقات جنگل و صنوبر ایران
سال بیست و هشتم شماره 4 (پیاپی 82، زمستان 1399)

Today, application of superabsorbent material as plantbac panels to overcome water shortages is considered for improving plant vegetation cover in arid areas. This research was aimed to investigate the effects of plantbac panels on plant establishment and growth of Calligonum comosum L’Herit. in the Kashan Arid and Desert Research Station over three years from 2017 to 2020. The experiment was conducted as a split plot design based on randomized complete blocks in four replications, in which the duration of irrigation (2 and 4 weeks) was considered as the main plot, and the amount of water (10 and 20 liters) and treatment (plantbac and control) as sub subplots. The seedlings were planted in the soils with and without plantbac panels. For each plant, the irrigation was conducted using 10 and 20 l water for two- and four-week intervals. Data were collected and analyzed in terms of plant height, canopy diameter, collar diameter, and survival rate. The results showed that the use of plantback plates increased the examined growth criteria of seedlings. When comparing interactions between treatments, the height, collar diameter and crown diameter of the Plantback treated seedlings showed average 11, 11, and 14.8% superiority to their controls. Furthermore, the interaction effect of irrigation by water consumption was significant for canopy diameter (p < /em> < 0.05), while interaction effect of irrigation by plantbac was significant for plant height (p < /em> < 0.05). The average higher and lower crown diameters of 83 cm and 39 cm were observed by 10 l water in two- and four-week irrigations, respectively.

This study aimed at selecting the most appropriate vegetation indices extracted from satellite images to study the effect of climate change on forest cover in the Sardasht, W. Azerbaijan province, Iran. Therefore, 25 plant indices were initially calculated from Landsat time-series images during 1988-2017, followed by applying principal component analysis (PCA), which led to the selection of nine more effective plant indices. The selected indices included seven indices in the first axis and two in the second axis. These two axes explained ca. 91% of the variance of the studied indicators. In addition, linear correlation coefficients between selected indices and climatic parameters were investigated using the data of the Sardasht synoptic station. The results showed that the indicators of the first and second axes were directly and inversely correlated with spring rainfall and temperature, respectively. The Soil Adjusted Vegetation Index (SAVI) showed 49% correlation with spring rainfall, while the Red Green Ratio Index (RGRI) revealed 51% correlation with the average spring temperature during the 30-year period. The association of SAVI and RGRI indices with precipitation and temperature in the last three decades showed a correlation of 84% and 51%, respectively, mainly due to the matching effects of precipitation and spring temperature in the first decade. However, correlation coefficients of both indices decreased to less than 50 and 10%, respectively, in the second and third decades. According to 1) the characteristics of the study area and the involvement of other factors that affect forest cover as well as 2) the opposite or similar effects of climate parameters on forest cover, application of the mentioned indicators to survey the effect of climate change on the Northern Zagros forest cover showed low to moderate correlations.

As one of the most widely used models for fire spread simulation, cellular automata models commonly require appropriate parameters and the optimized coefficients. The main aim of this study was to compare the basic models of cell automation set by previous studies and optimized models using the Bee Colony Algorithm (ABC) to predict the rate of fire spread in a reforestation area in northeastern Golestan province, Iran. Furthermore, a sub-objective was to test the ability of optical and radar sensors (Sentinel 1 and 2) for mapping the vegetation stand type and density required for fire spread modeling. Following pre-processing and extraction of vegetation indices, vegetation type and density were mapped by the Random Forest algorithm. The accuracy assessment showed that the best result was obtained by combining the optical and radar data (Kappa coefficient (KC) = 0.75 and Overall accuracy (OA) = 0.81). Moreover, the fire spread was modeled using previous and optimized coefficients from previous studies. Model coefficients were optimized based on environmental conditions using the BCA algorithm and were compared with the occurred fire to improve the results and comparative evaluation. The results showed that the optimized models were more consistent (Sorenson coefficient (SC) = 0.78; KC = 0.74 and OA = 0.93 for Alexandridis et al., 2011; and SC = 0.78; KC = 0.74 and OA = 0.92 for Alexandridis et al., 2008) with the observed fire than the other applied cellular automation models.

Sweet cherry (Cerasus avium (L.) Moench.) is an endangered species in Iran, which necessitates the preservation of its genome. Cryopreservation condition storage is an efficient way for long-term maintenance of the germplasm. To store sweet cherry seeds in cryopreservation conditions in this study, the first treatment was to dehydrate seeds to prevent free water crystallization and rupture of the plasma membrane at cryo temperatures. Therefore, 30% glycerol pretreatments, vitrification solution, and reduction of seed moisture were used before entering liquid nitrogen. The treated seeds were exposed to heat shock after taking out from liquid nitrogen, followed by examination of their seed survival and germination. The nitrogen control treatment showed the highest survival and germination percentage. Some cryopreservation treatments reduced germination percentage, since they reduced seed moisture. Furthermore, the highest germination percentage (40%) was found in seeds that were not treated with any moisture reduction. Therefore, cryopreservation preservatives impair seed germination. As a result, the amount of moisture in the seed is the minimum amount of moisture needed for survival and germination, and reducing the moisture will damage the seed embryo. Thus, by using cryopreservation technology and applying pretreatment without reducing moisture, the seeds were collected from four different regions and stored in the cryopreservation bank of the Research Institute of Forests and Rangelands in Iran, in order to preserve this species for long term.

Due to its variety of attractions, Jahan Nama forest park is one of the essential tourist attractions in the Alborz Province, Iran. Therefore, studying recreational value can support prediction of the requirements and shortages, which leads to tourism development. This study aimed at determining the recreational value of Jahan Nama forest park and visitors´ willingness to pay by using a conditional valuation method and a two-dimensional dual choice questionnaire. The statistical sample consisted of 350 forest park visitors who were selected based on available sampling method. The logit model was used to investigate the effect of explanatory variables on the rate of visitors' willingness to pay. The results showed 74.9% of the respondents were willing to pay for recreational use of the forest park, with an average willingness to pay of 15,781.6 IRR for recreational values per visit. The total annual recreational value was estimated to be 10,258,040,000 IRR. The variables of the proposed rate of payment, age and the cost of transportation per visit were negatively affective, whereas park quality, marital status, duration of reading per week, environmental attitude, education, income and gender, had a positive effect on willingness to pay were positively influential. The results showed that people are aware of the importance of forest parks and natural environments, with a significant willingness to pay that can support officials in forest park planning and management.

Forest decline is the result of the interaction of factors such as climate, especially the occurrence of drought and early frost, tree age, habitat quality, pests and diseases, and the phenomenon of dust. The aim of this study was to measure the amount of dust particles deposited on oak in a forest stand in Ilam province and to investigate the biological characteristics of healthy trees and trees hosting oak charcoal disease. In order to measure biochemical traits, study of antioxidant activity and enzymes, amount of dry dust deposition on the leaf, random sampling was performed from different parts of the crown of each rootstock. On the leaves, sampling was randomly selected from different parts of the crown. The mean dry dust deposited per unit area of oak leaves for healthy and diseased trees during three sampling periods was 0.21 to 0.26 mg / cm. The amount of chlorophyll a, b, total and carotenoids in healthy and diseased trees was significantly different. 0.038, 0.06, 0.1 and 0.14 in healthy trees, respectively, more than 0.3, 0.05, 0.08 and 0.12 in diseased trees. Also, the amount of antioxidants and catalase in healthy trees were 56.9 and 0.01, respectively, with a significant difference greater than the diseased trees of 42.8 and 0.008. The amount of phenol and flavonoids in diseased trees (169.9 and 47.8) is more than healthy trees (114.5 and 36.6).

The extent to which plants can protect soil largely depends on the biotechnical characteristics of their root system. One of these characteristics is the root distribution pattern in the soil or the Root Area Ratio (RAR). The aim of this study was to investigate the effect of altitude on the root spatial distribution of Caucasian alder (Alnus subcordata C. A. Mey.)trees in lower, middle and upper altitudes in the Neka-Zalmrud forestry plan in the Mazandaran province, Iran. At each site, seven trees were completely randomly sampled. In order to investigate and measure RAR, two soil profiles were dug at both up and down sides of tree samples (with 50×100 cm2 dimensions) using the profile trench method at the horizontal distance of 0.5 and 1.5 m from the tree stem. On wall trenches, 10 cm horizons were identified, on which all intersecting roots were measured and RAR was calculated in each horizon. At all three altitudes, RAR decreased exponentially with increasing depth and distance from the tree. The results of ANCOVA showed that the distribution of roots at all three altitudes was significantly different. In overall, the density of the roots increased along with increasing altitude above sea level. Higher percentages of RAR in some locations at lowland heights were probably due to limited soil depth at this height.

In this study, the diversity of morphological traits of needle in male and female yew (Taxus baccata L.) along the topographic and longitude gradients in the Hyrcanian forests was studied. To this aim, a total of 580 needles from 58 trees were measured in three sites (Amlash, Gazu and Afratakhteh) along the longitudinal gradient of the Hyrcanian forests. A hierarchical or nested analysis of variance was used to assess influencing sex and site on the 6 measured morphological traits of needles. In addition, Duncan's test was used for multiple comparisons of means. Furthermore, principal component analysis (PCA) was used to determine the most important traits and environmental factors in differing sites. Results showed that variation of morphological traits of yew needles is only affected by site factor. However, the influence of sex was not significantly assessed. Results also showed that most morphological traits of yew needles except the form factor were highest in Gazu site that comprised moderate slopes, northern aspects, faced northern humid air and experienced higher growing season due to lower elevation. Generally, morphological traits of yew needles were lowest in Amlash site, which included steep slopes (loss of soil depth) and western aspects (decrease in relative humidity). Yew trees in Afratakhteh site showed intermediate values. Our results imply that sites with cool summers and higher relative air humidity (settling in the humid northern valleys) provide more favorable growth conditions to morphological traits of yew needles compared with sites with higher average annual rainfall across the Hyrcanian forests.