جستجوی مقالات مرتبط با کلیدواژه « قطر یقه » در نشریات گروه « جنگلداری »

The single tree selection method was applied in the Hyrcanian forests of northern Iran to imitate nature and enhance the ecosystem characteristics and functions such as biodiversity, flexibility, and adaptability. However, the effectiveness of this imitation and the changes in the forest stand characteristics were unclear. This research compared the regeneration characteristics of tree species in canopy gaps larger than 100 m2 in a beech (Fagus orientalis Lipsky) stand in the Hyrcanian forests that underwent single tree selection in 2013 with an unmanaged beech forest as a reference. The abundance of seedlings and saplings of all tree species was recorded in each microplot (with an area of 4 m2) in the center and four edges of each gap. The height, collar diameter, crown width, health, stem form, and mode of branching of beech saplings were also measured in each sample microplot and compared. The results indicated that the mean collar diameter (26.6±2.2 mm), height (270.4±23.6 cm), and frequency of orthotropic beech saplings (0.3±0.06) in the managed compartment were significantly higher than the unmanaged compartment (p < 0.05). The average frequency of regeneration in the managed and unmanaged compartments was 7.9 and 6.3 per microplot, respectively. The frequency of beech regeneration in the managed compartment was higher in large gaps, while it was higher in medium gaps in the unmanaged compartment. Although the low harvesting in the studied forest improved the growth conditions for beech seedlings, the abundance of dead trees should be considered. Moreover, the presence of Hedera pastuchovii Woron. exGrossh. in these forests should be examined and managed accordingly.

The slow growth of hazelnut seedlings, particularly during the initial years of afforestation, hampers the rehabilitation and development programs of hazelnut forests. In this context, biological fertilizers, especially plant growth-promoting bacteria, can be an effective strategy to enhance the growth and physiological traits of hazelnut seedlings. In May 2017, new hazelnut potted seedlings from two seed sources - Fandoglou (Ardabil Fandoglou forest) and Makesh (Aghvalar Guilan forest) - were propagated in an Ardabil hazelnut nursery. These seedlings were inoculated separately and in combination with Pseudomonas putida DSM291, Bacillus subtilis FzB24, and Enterobacter cloacae E1. In November 2017, the one-year-old hazelnut seedlings were transferred to agricultural lands bordering the Fandoglou forest. The seedlings were planted in rain-fed conditions following a randomized complete block design with three replications of 12 based on two factors: fertilization and seed origin. After four years, it was observed that inoculated seedlings from both origins outperformed non-inoculated ones in all investigated traits. The largest parameters of the studied variables were attributed to the Fandoglou-origin seedlings inoculated with a combination of three bacteria. These seedlings showed a survival rate of 49.7%, collar diameter growth of 51.1%, height growth of 60.4%, and dry mass increases in roots (85.6%), stems (75.1%), and leaves (68.2%). Additionally, photosynthesis increased by 49.9%, stomatal conductance by 58.04%, water consumption efficiency by 121.7%, and chlorophyll content by 46% compared to non-fertilized Fandoglou-origin seedlings. In conclusion, considering the role of the studied growth-promoting bacteria (especially the combined treatment) in enhancing the growth characteristics and physiology of hazelnut provenances, inoculating hazelnut seedlings with bacteria in nurseries can be a beneficial strategy for successful field transplantation.

Mangrove forests are fragile ecosystems that are very sensitive to human activities. For this purpose, in this study, for the first time, effects of desalination sewage on vegetative characteristics and vitality of mangrove seedlings have been investigated. After collecting propagules from healthy mother trees and planting them in September 2020, propagules were irrigated twice a day with water treatments of 0, 1, 2, 3, 5, 10 and 20% concentration of desalination sewage. After 6 months, vegetative characteristics and vitality of seedlings were measured in different treatments and compared using ANOVA and Kruskal Wallis test. The results showed that diameter growth (3.40 mm), height growth (50.10 cm), root length (33.58 cm) and leaf area (21.67 cm2) were the highest in the control treatment. Also, the number of leaves and the degree of vitality had significant differences in  different treatments. Also, control and 20% concentration treatments (24 and 30.41 mS.cm) had the least and highest amounts of soil salinity (p<0.05), respectively. The results showed that desalination sewage has a negative role on the vegetative characteristics of mangrove seedlings. The higher concentration of desalination sewage, the greater negative effects on vegetative characteristics. Totally, the critical effect of desalination sewage concentration on the vegetative characteristics of mangrove seedlings could be reported from 10% concentration. Therefore, it was recommended to use suitable management programs in the use of desalination set and sewage remove in order to minimize the mangrove forest damages.

Drought stress is the most important factor in the growth of plants in arid and semi-arid regions and plays an important role in the establishment of plants in these ecosystems. Russian olive seedlings were planted in environmental plan in the form of Complete Randomized Block Design (RCBD) with four replications and treat mental plan in the form of factorial with 2 factors in the greenhouse. The test factors were Arbuscular mycorrhizal inoculum (Rhizophagus irregularis, Funneliformis mosseae and control without inoculation) and four drought stress intensity (25, 50, 75 and 100% of field capacity (FC)). Seedlings growth rate include height, collar diameter, number of leaves, number of branches, weight of aerial and underground organs was calculated by comparison of the growth rate at the beginning and end of the experimental period. With increasing drought stress intensity, vegetative traits such as height, collar diameter, number of branches and leaves, root dry weight and shoot dry weight of Russian olive seedlings were decreased significantly. With increasing drought stress to 50% of FC, the main root length of seedlings showed an increasing trend, indicating an increase in root length under dehydration. The highest and lowest dry weights of seedlings shoot were observed in treatments of F. mosseae and control, 36 g and 18 g, respectively. Fungal species of F. mosseae in all morphological traits except root dry weight provided more favorable conditions for the seedlings, as well as the F. mosseae, showed more abundance and better coexistence with Russian olive seedlings.

In a study of growth and morphological differences among Populus caspica Bornm., trees within Hyrcanian biogeographical region, 15 stands were selected from which one-year cuttings were cut from three plus-trees in each stand. The cuttings were planted in March 2017 at Chamestan Research Station, and the rooted cuttings were cut from the collar base after one year. Cuttings were separated from the one-year sprouts in the next winter and planted based on Randomized Complete Block Design with three replications. We sampled five leaves of each stand-tree seedling on late June and 17 leaf morphological and growth traits as well as collar diameter and height of the rooted cuttings. Data were analysed by hierarchical cluster analysis, two-way ANOVA and Duncan comparison of means test. Four groups were separated according to cluster analysis, among which rooted cuttings from Golestan province showed the highest morphological diversity. The maximum and minimum collar diameters and height growth were observed in seedlings originated from Rostam-Abad (Guilan province) and Golestan National Park (Golestan province) respectively, yet they were similar in some of their morphological traits like their minimum leaf width at 10% of the total length, maximum leaf width, lobe depth and number of veins, which id presumably due to the location of their mother stands at the border of Hyrcanian and Irano-Turanian regions. Thus, they can be considered as morphological traits of P. caspica in the ecotone regions. However, the two regions had a high value for conservation, especially in Rostam-Abad due to high growth rate as well as prominent morphological differences in comparison with the other genotypes. Therefore, they are suggested for being integrated in tree improvement programs in the future.

This research was carried out in Sirachal Research Station in order to identify the best method for Greek juniper (Juniperus excelsa M. B.) afforestation as one of the most important forest species in Iran. Three year-old juniper saplings were transported to Sirachal and were planted in a Split-Plot Randomized Block Design with water harvesting (in 5 treatments including using organs of native plants and shrubs at the bottom of pits, using 1×1 m plastic film at the surface of pits, using Aquasorb polymers mixed with the pits soil, semi-circular bonds and control) as main factor and shading (in 2 level of using tree sprouts as artificial shading and control) as secondary factor in 3 replication and 16 saplings per replication. Measured variables were survival, collar diameter, height, and crown area and sapling vitality at the end of growing season of 2015 and 2016. Results showed that rainwater harvesting had significant effect on survival juniper saplings for both 2014 and 2015 years and current annual increment of collar diameter. The highest value of these parameters was noticed for plastic film treatment though the highest decrease of survival from 2014 to 2015 was noticed for this treatment too. Both rainwater harvesting and shading had no significant effect on height, crown area, vitality and their changes during the studied years. Overall, results confirmed the possibility of rainfed afforestation of Greek juniper in high altitude of Southern Alborz Mountain. To achieve this goal, usage of nylon at the surface of plantation pits is recommended. There is no need to use artificial shading for planted saplings.

A study on the impacts of soil humidity and artificial shading on growth, biomass production and its allocation to different organs of wild pistachio (Pistacia atlantica Desf.)saplings was carried out in Alborz research station complex (Karaj, Iran). One year seedlings were treated by soil humidity (20, 50 and 100 percent of field capacity) and shading (100, 70 and 50 percent of full sunlight) factors in a split plot experiment based on a randomized complete block design from June to December 2014. Results showed significant impact of oil humidity on height, collar diameter, fresh and dry biomass of leaves and stem as well as on total fresh biomass. Shade significantly decreased height, root and total dry biomass and root to shoot fresh biomass ratio. Moreover, wild pistachio saplings with different soil humidity treatments show different responses to shade. In particular, shade significantly decreases height, fresh leaves biomass and R/S fresh biomass ratio for well-irrigated saplings and increases these parameters for saplings under drought stress. Response trends of different parameters under humidity × shade treatments showed that shade can reduce undesirable effects of drought stress on wild pistachio saplings.

In order to investigate some silvicultural and soil physico-chemical characteristics of Christ's thorn (Ziziphus spina christi L. Desf.) natural stands, ten natural stands of the tree species which have similar climate and aspects were selected and altitude from sea level (ASL), the thickest sprout collar diameter (TSCD) and total tree height (TH) of the tree species were measured in 1000 m2 circular main plots. Seedling regenerations of the species were counted in 100 m2 circular microplots. We sampled soil from three depths of 0-30, 31-50 and 51-70 cm for studying on soil physico-chemical properties in each main plot. To compare means of tree quantitative characteristics, t-student, ANOVA and Duncan and for soil studying, CA and PCA were used. The results showed that TSCD and TH hadnt significant differences in two levels of ASL. Although there were an exclusive correlation between presence of the species and sand percent of all three layers of soil in around 60% of Christ's thorn sites, the minimum TSCD were recorded in the sites too. Christ's thorn had the maximum TSCD in sites correlated with N, OC and EC in shallow and percent of silt and clay in deep layers of soil. So for increasing success of Christ's thorn plantations we suggest such sites are selected.

Diameter is such a notable characteristic in forest inventory that it is important to have a suitable method of its measurement, especially in coppice trees. This seems more important in Zagros forests that most of them are covered with coppice trees. So this research was aimed to find an efficient method in studying the diameter at root collar (DRC) of Persian Oak coppice trees as the most important species in Zagros forests. For this purpose, DRC by two methods, crown area and height and tree height were measured in 235 Persian Oak coppice trees. The results showed that the average of DRC by the first method (24.06±12.69 cm) was significantly different from the second method (13.03±7.22 cm) and it had higher significant correlation with other characteristics. Also the linear relation between DRC by two methods and other characteristics showed the higher significant correlation of the DRC measured with the first method. So it is concluded that the first method applied in this research is an efficient method in DRC studies in Persian Oak coppice trees of the study area. Also it can be recommended to assess this method in other coppice trees of Zagros forests and if proved, it can be applied to all coppice trees in Zagros forests.

This experiment was conducted in Rikhalan Experimental Station in Marivan city of Kurdistan province of Iran in 1999 and ended in 2006. In first phase, (nursery selection) 29 genotypes of walnut (Juglans regia L.) were studied, under Randomized Complete Blocks Design (RCBD) with four replications in three years. The measured tree characteristics were: height, collar diameter and survival. Based on the results of first phase, for the second phase, five genotypes of walnut (J–2, J–10, J–17, J–18 and J–19) were selected and planted under Split Plots Design with three replications during seven years (1998–2006). The main plots were: Control and soil surface with mulch cover and the secondary plots contained five walnut genotypes. Results showed that there were only significant differences between the main treatments in respect to the growth characteristics (p < 0.01). Survival, crown diameter, height and collar diameter of the walnuts at plots applied with plant material mulch (oak chipped branches) were significantly greater (96.7 %, 72.6 cm, 135.9 cm and 37.4 mm, respectively) than the walnuts at control plots (77.9 %, 50.1 cm, 95.6 and 28.4 mm, respectively).