مجله پژوهش و توسعه جنگل
سال هشتم شماره 4 (زمستان 1401)

In order to achieve the goals of sustainable forest management, single tree selection method was implemented in Hyrcanian forests. But it is not clear what effect the implementation of this method has on the reproductive characteristics of trees in forest stands. For this purpose, we compared the quantitative and qualitative characteristics of beech seedlings and saplings in the gaps of two managed and unmanaged compartments. Expanded gaps with an area > 100 m2 were identified in the two compartments. Except of density and richness of tree species, the average of other quantitative characteristics of saplings was significantly (ρ<0.05) in the unmanaged than the managed compartment. While the highest frequency of healthy and unforked seedlings was observed in the managed compartment (ρ<0.05). Species richness in both compartments showed a low value. Considering that one of the goals of sustainable forest management is to increase the diversity of trees and adapt to the ecosystem, it is necessary to pay attention to the promotion of the diversity and richness of tree species in the future management plans in the studied areas.

The aim of present study is investigating the effect of physiographic factors on leaf area index (LAI), leaf mass per area (LMA) and canopy water content (CWC). 125 square plots with dimensions of 30 meters by 30 meters in cluster method model were sampled. Plot elevation was determined by using digital elevation model (DEM) map. Also 9 aspects were determined by using a compass device. Photographing the canopy and collecting leaves from the canopy were done to estimate the indices. The results showed that the elevation has a significant effect on all indices. The aspect has a significant effect on LAI and LMI indices. LAI and CWC indices decrease from low to high elevations and increase on the highest elevation. The LMA attribute also increases from low to high elevations and decreases in the highest elevation class again. The high LAI value observed in the north and northeast aspect and the lowest LAI observed in the south and southwest aspects. The CWC is higher in northern aspects and it is lower in the southern aspect. LMA is lower in the northern and northeastern aspects while it was higher in the western and south western aspects. Knowing the conditions of vegetation indicators status in different aspects and elevations, provides the possibility of prioritizing support and maintenance measures in different topographical conditions of the region.

In this study, machine learning based models (linear regression, k-nearest neighbor, support vector regression, random forest) were evaluated to estimate carbon sequestration and soil respiration in the forests of eastern Mazandaran province. After identifying the sampling points, in each plot, the diameter and height of the trees were measured and the above-ground biomass of the trees was calculated using allometric models of Hyrcanian forest. Soil samples were taken from 0-20 cm depth and soil respiration was measured by CO2-port. Soil respiration was estimated using bulk density, moisture content, texture, soil temperature, total nitrogen, available phosphorus and potassium, organic carbon and above-ground trees biomass. Soil carbon sequestration was estimated using soil temperature and moisture and above-ground tree biomass. Random forest model (RMSE = 10.47 and R2 = 0.82) and support vector machine (RMSE = 0.77 and R2 = 0.90) had the highest performance in estimating carbon sequestration and soil respiration, respectively. Soil moisture had the highest relative importance in estimating carbon sequestration (random forest model) and soil respiration (support vector machine model). According to the obtained results, it is possible to estimate the amount of carbon sequestration and soil respiration in the forest with appropriate accuracy by having the above-ground biomass of trees and basic soil characteristics.

The aim of this research is to evaluate the characteristics of wild-type genotypes of Hackberry (Celtis australis) in the East Azerbaijan province in order to use in breeding programs. In this research, 22 genotypes were collected and physical characteristics of fruit, seed and leaf were examined. The results showed that the length of fruit varies between 8.29 to 10.01 mm and the largest fruit is related to the C10 genotype. According to the results of factor analysis, the six main factors were explained more than 88.3% of the total variance. In the cluster analysis based on ward method, genotypes were divided into three main groups. The first group consisted of 11 genotypes (C1, C11, C4, C9, C8, C15, C19, C21, C2, C10, C16) with the highest mean of fruit length, fruit width, seed width, fruit weight, sphericity, geometric mean diameter and hue index. In the second group, 6 genotypes (C3, C5, C14, C20, C22, C17) were located with the highest mean seed length, petiole length, seed weight, a* and chroma. The third group included 5 genotypes (C6, C7, C18, C12, C13), which the leaf length, leaf width, and surface area had the highest effect in separation of genotypes in this group. As a result, the obtained results of present study can be useful for breeding programs and introduction of cultivar in Celtis australis.

Taxus is one of the most valuable plant resources that has a variety of benefits and uses. The leaves of this plant are a good source for extracting an anti-cancer drug called Taxol. Today, therapeutic approaches for use herbal medicines have been developed, so the study of the biosynthetic pathway of medicinal plants is important. In the present study, plant samples were treated with Methyl Jasmonate at different concentrations of 0, 100, 250 and 500 μM and kept for 48 hours and 72 hours. After treatment, dbat gene expression was measured by Real Time PCR, also the amount of Taxol produced was examined by High-performance liquid chromatography (HPLC) and the obtained data were analyzed. The results showed that at 72 hours, the expression of dbat gene at a concentration of 250 μM was 1.68 times higher than the control plant. In addition, at 48 hours and 100 μM, the expression of dbat gene was lower than all treatments. Also, the highest amount of Taxol produced in the treated plant was observed with a concentration of 500 μM Methyl Jasmonate and a time of 48 hours at the rate of 0.3276 mg / g dry weight. Pearson correlation test showed that there was no significant relationship between gene expression and Taxol production. This may be due to the difference between the expression time of the gene and the Taxol produced under the influence of the Methyl Jasmonate.

Plant endophytic fungi play an important role in the physiological and biochemical interactions of plants in response to environmental conditions and by producing specific secondary metabolites. In addition to preserving the host plant, they also gain economic importance. In this regard, the identification of endophytic fungi of Arasbaran Cotoneaster integerrimus shrub was targeted. Leaf and stem samples were isolated from the plant and, after surface disinfection, were cultured in a PDA medium containing Streptomycin. After growing fungal hyphae and culturing them, the PDB medium was used to continue the work. To identify the grown fungal, DNA extraction was performed and Polymerase Chain Reaction was performed using Internal Transcribed Spacer (ITS) primers. PCR results showed that out of 15 isolated isolates, the ITS fragment was amplified in 9 isolates. As 3 isolates in Penicillium sizovae, three isolates in Alternaria alternate, two isolates in Penicillium and the last isolate were not named due to the low similarity of its ITS sequence with the database data and it is probably a new species and needs further studies. Phylogenetic analysis identified the four species in two completely distinct clades, so that the lowest genetic distance observed between the two Penicillium species and the maximum distance observed between the Penicillium sp and Fungal sp. The present study is the first report on Cotoneaster integerrimus endophytic fungi and shows that this plant hosts a small number and range of endophytic fungi.

Fire has different effects on soil quality and its physical, chemical and biological properties. In order to investigate these effects, in this study, various physical, chemical and biological properties of soil in a part of Arasbaran forest located in Kalibar city that were affected by fire were studied. Soil samples were taken from burned areas (32 samples) and adjacent areas that were not affected by fire as blank samples (32 samples) by systematic random method from a depth of 0 to 15 cm and different soil properties were measured. The results showed that the values of pH, organic carbon, total nitrogen, moisture content, basal respiration and soil microbial biomass in the blank samples were significantly higher than the values in burned samples; while the highest amounts of absorbable P and K and bulk density were observed in burned samples. There was no significant difference in the percentage of sand, silt, clay, porosity, PD and substrate Induced Respiration in the blank and burned samples. Based on PCA analysis, absorbable P and Microbial Biomass Carbon were significantly affected before and after fire, respectively. The results of this study showed that the chemical and biological properties of Arasbaran forest soils (except P and K) were more affected by fire than physical properties.