مجله پژوهش و توسعه جنگل
سال نهم شماره 3 (پاییز 1402)

Depending on the purpose, different species of broadleaf and coniferous trees are used in the urban green space, which has diverse and complex characteristics. In this study, to obtain accurate information about trees and to cover the weaknesses of two technologies, TLS and TOF, their combination was used. For this purpose, 20 trees were selected from broadleaf (Fraxinus Ornus L. & Ulmus umbraculifera) and coniferous (Cupressus sempervirens L. & Cupressus arizonica Greene) species in the green space of Khajeh Nasir Toosi University and their point clouds were produced using TLS and TOF. After processing point clouds, the parameters of breast diameter, basal area, and crown area were measured. The RMSE of measuring the diameter at the breast of broadleaf and coniferous trees using TOF technology was 0.33 and 0.38 cm and TLS technology was 0.59 and 0.62 cm respectively. The diameter measurement error of the broadleaf is less than the coniferous due to the thinner bark. The basal area measured using TOF technology is more accurate than TLS; On the other hand, TLS technology has a precise and unique function in measuring the crown area. The basal area and crown area of broadleaf trees showed more errors than coniferous trees due to the asymmetric and irregular shape of the stem and crown. According to the obtained results and the examination of the strengths and weaknesses of these technologies, the combination of these two leads to more accurate and comprehensive results. Therefore, it is recommended to use the integration of these technologies in detailed scientific studies that are the basis of executive works.

Several methods have been proposed to evaluate soil quality in line with its management and provide suitable management solutions. Visual assessment method of soil disturbance provides a quick and effective tool for cheap evaluation of the quality of the soil in the field. The method of visual evaluation of soil degradation provides a quick and effective tool for cheap evaluation of soil quality in the field. The aim of this study was to visually assessment of soil disturbance due to forest operation by short wood and full tree methods in western plantations of Guilan province. For this purpose, 625 plots were measured in each method based on visual soil assessment method. The results showed that the studied operation methods destroyed different proportions of field areas so that 79.36 and 69.92% of the total area were destroyed in the short wood and full tree methods, respectively. Logging residuals in short wood method was more than in full tree method. The results showed that soil compaction in the short wood method (18.72%) was higher than in full tree method (14.08%). Logging residuals, shallow disturbance and soil compaction were the most common types of soil disturbance cause by logging methods, therefore the highest amount of disturbance in both methods was related to the logging residuals class. The results of Mann-Whitney U test showed that there was a significant difference between the two forest logging methods. In general, the results showed that the type of timber removal method in logging operations and skidding has a significant effect on forest soil disturbance.

One of the concerns for the executive organizations to introduce an alternative plan of rest of the Hyrcanian forests is to make decision regarding the exit of coarse woody debris (CWD) volume from the Hyrcanian forests. The research was carried out in the permanent plot with 400 m2 based on the protocols of the comprehensive research plan enacted by Agricultural research Education and Extension organization in Iran. Within each plot beneath the CWDs over than height of 1.5 m and dimensions of 7.5 cm, the organic accumulations resulted from the decay trend were sampled. Besides, the soils mineral layer up to 10 cm depth were sampled after removing the organic accumulations, and were transported to the laboratory. The results of PCA (Principal Component Analysis) showed that beneath the CWDs including higher organic accumulations, amount of the organic carbon and the nutrients were lower in the substrate soil mineral layer. Furthermore, the results of Spearman test indicated that amounts of organic carbon and nutrients in the organic and substrate mineral layers were independent of each other (P > 0.05), and amounts of the organic carbon with Nitrogen were significantly correlated (P < 0.01). Also, the results of two-way PERMANOVA test indicated that interactions of form, species and decay of the CWDs in the study sites were not significantly effective on the organic carbon under the CWDs.

Quantitative description of forest stands in terms of the composition and species diversity is used as one of the most important tools in forest management. This research investigates the composition and species diversity of the coppice with standard stands of Arasbaran forests. In order to carry out this research, 24 rectangular sample plots with an area of ​​half a hectare (with dimensions of 50 meters by 100 meters) were randomly surveyed in the study area. Inside these samples, the structural characteristics of the stands, including the species, Coppice shoots, the diameter and the height of the sprout-clump, were measured using the 100% statistical method. Shannon-Wiener diversity index, Margalf richness and Pylo's uniformity were used to check biodiversity. The results showed that Carpinus betulus L. (63.8 percent) was the dominant species and Quercus macranthera (26.7 percent) and Acer campestre (4.5 percent) were among the species with the highest abundance. The average height and DBH were 6.45 meters and 12.14 cm, respectively. The highest and lowest values ​​of the biodiversity index are related to the Pylo index (1.01) and the Margalef index (0.71). The research showed that the diagonal distribution of the stand indicates that the stand is of the same age and young, and the bell shape of the height distribution also indicates the accumulation of the most searches in the middle altitude classes.

To investigate the effect of drought stress on the vegetative, physiological, and biochemical characteristics of purple seedlings, an experiment was conducted in the form of a completely randomized design with four levels of irrigation including 75% (mild stress), 50% (medium stress) and 25% (severe stress) of the field capacity (FC) and the control (100% FC) in greenhouse conditions. The results showed that severe drought stress significantly reduced vegetative traits such as seedling height growth (86.8%), the number of leaves, and total fresh and dry biomass by 93%, 46.2%, and 44.8%, respectively, but increased root volumetric growth (1034%). Also, drought stress affected all parameters of gas exchange and photosynthetic pigments. So that at the level of 25% FC, it caused a significant decrease in the rate of photosynthesis (1/20 µmolCo2m-2s-1), transpiration (0/65 mmolm-2s-1), stomatal conductance (106/2 mmolm-2s-1) and mesophilic (0/0088 mmolm-2s-1), intracellular carbon dioxide concentration (134/2 mmolCO2 m-2s-1) and carboxylation efficiency (0/00112 µmolCO2 mol-1H2O). The amount of photosynthetic pigments (chlorophyll a, b, total chlorophyll, and carotenoids) also showed a significant decrease at 25% FC (4.07, 1.96, 6.03 and 1.23 mg g-1 FW, respectively.). Also, drought stress increased the amount of proline and soluble sugar and showed the highest values at the level of 25% FC (respectively, 1.348 µmol g-1 FW of proline and 41.51 mg g-1 FW of soluble sugar). According to the above evaluations, it seems that the purple variety can tolerate drought stress up to 75% FC without causing damage to the plant tissue, but if the amount of water is reduced to the threshold of 25% FC, its growth and performance will be severely affected.

The purpose of this research is to investigate the quantitative and qualitative characteristics of the Quercus branti stands in the altitude classes and to estimate the amount of its fruit production in the investigated stands; therefore, in the three altitudes classes of Sardasht forests (below 1400 m, 1000-1400 m, and over 1400 m), the study area were chosen and 27 transects were randomly taken. In the sample, characteristics such as species, height, dbh, small and large crown diameter, trees origin, health and distance between trees were measured. To estimate the fruit, the number of fruits produced from 116 stems in different diameter classes were visually counted and weighed. Based on the average weight of 100 fruits, the weight of all individuals was calculated. The results also showed that Quercus branti coverage was the highest in the altitude layer less than 1000 m and it decreases with the increasing altitude. The average d.b.h (36.16 cm), the crown diameter (6.34 m), and the total height (6.71 m) are the highest in the altitude class below 1000 m. D.b.h as an important variable showed a significant positive correlation with the amount of fruit produced by selected trees. This research showed that with the increase in altitude, the presence of the Quercus branti decreases, and the quantitative and qualitative characteristics of trees show significant differences. Based on the results, it is suggested to use more Quercus brantii species in rehabilitation and enrichment programs in the altitude class of less than 1000 meters.

The objective of this research was to estimate the biomass, carbon storage and leaf area index of hawthorn species (Crataegus aronia L.) in Sartaf forests of Ilam city. For this purpose, using random sampling method, 30 hawthorn trees were selected and variables of collar diameter, tree height, crown length and large and small diameter of the crown were measured. Then, the leaves from 1/4 or 1/8 of the crown of sample trees were collected. After drying the leaves in the oven, the dry weight of the leaves was determined. After burning a sufficient amount of dried leaves in an electric oven, the weight of organic matter and carbon content of the leaves were obtained. The weight method was used to calculate the leaf area index. The results showed that the average leaf biomass, leaf carbon sequestration, and carbon dioxide absorption from the atmosphere were 99.18, 46.61, and 170.59 kg per hectare, respectively. The average leaf area index of hawthorn species was calculated as 9.08 for each tree and 0.095 per hectare in study area. The results of allometric relationships using different regression models showed a positive and significant correlation between the variable of mean crown diameter with the variables of biomass and leaf area index of hawthorn trees in Ilam forests. In general, the results of this research show the ability of using allometric equations to measure biomass, carbon sequestration, and leaf area index of Crataegus aronia.

The aim of this study was to investigate the spatiotemporal dynamics of trees distribution patterns in a ten-year period following disturbance caused by decline in the oak forests of Lorestan province in the west of Iran. For this purpose, the quantitative characteristics and the spatial patterns of trees in 5-hectare sample plots in four different regions without decline, which were surveyed in 2010, also surveyed in 2020 which three regions had conditions of decline and one region without decline). The results showed that the mean of density was decreased in declined areas and increased in the non-declined area during the period. During the ten-year period, there was a significant difference between the tree density and canopy percentage in the areas with and without decline. The spatial patterns of Persian oak (Quercus brantii) trees in the decline areas showed that during the period, the spatial patterns in the pure and low-density stands were clustered, while in the mixed stands with the dominance of oak with relatively high density, it was a random distribution pattern, which with increasing of distance, changed to clustered. The disturbance due to decline in the mixed stands caused the clustering occurred in a smaller radius (40 meters and more), but in the mixed stands without declined clustering observed in a radius of more than 60 meters. The results of this study showed that the trees decline affects the spatial patterns of trees which can be an effective guide in the management of decline stands.

Despite the potential of the Hyrcanian forests to maintain of Quercus castaneifolia, the abundance of this species has decreased drastically and most of the young stands of this species are seriously threatened. This research, using an integrated perspective, shows the distribution Q. castaneifolia species in the Hyrcanian forest with the aim of determining the optimal areas for reforestation using five different modeling methods including GAM, GLM, RF, CTA, and GBM. Rainfall and temperature maps are based on data collected from a network of weather stations, as well as soil data from Soil Grade database maps. Then, the most important independent variables affecting the distribution Q. castaneifolia were identified. The results obtained from the evaluation of the relative importance of the variables indicate that the amount of organic carbon, pH, changes in seasonal rainfall and rainfall in the coldest season of the year have the greatest relative importance in determining and developing the habitat of this species and the area has a favorable potential of 14.1 The percentage is for this species. The produced habitat suitability map is suggested as a basis for future forest restoration plans, especially in areas that are more affected by destruction.