جستجوی مقالات مرتبط با کلیدواژه « morphological characteristics » در نشریات گروه « جنگلداری »

The present study was conducted with the aim of mass production of seedlings of Populus deltoides Marsh. and P. euramericana (Dode) and to investigate the vegetative yield of the produced seedlings. In the first phase of the study, the collected seeds from the poplar collection of Chamestan Forest and Rangeland Research Station were sown in two treatments of pure field soil and soil mixed with sand, and three seed densities in three replications. Then, the number, dimensions and some morphological characteristics of the produced seedlings were investigated. In the second phase of the study, 12 genotypes were selected from the offspring of each of the two species. Sufficient cuttings were obtained from them and planted with cuttings of mother trees in three replications. Their vegetative characteristics were also recorded and analyzed. The results of the first stage showed that the range of changes in diameter, height, number of leaves, leaf length, survival percentage and percentage of seedlings longer than one meter in P. euramericana 92/40 seedlings was significantly higher than P. deltoides  69/55 seedlings. In terms of diameter, height and percentage of seedlings higher than one meter, the pure field soil was significantly superior to the mixed soil. Survival for densities of 50, 100 and 200 seeds per square meter was 32.8%, 19.8% and 10.25%, respectively. The results of the second stage showed that the height and diameter of the mother bases were less than the offspring. The selected genotypes of this study include genotypes 10, 12 and 2 from the offspring of P. deltoides 69/55 and genotype three from the offspring of P. euramericana 92/40 which can be introduced to the implementation section for spacing cultivation experiments, stress resistance study and development of wood cultivation.

The current research was planned to investigate the effect of maleic anhydride (MAN) and glycidyl methacrylate (GMA) treatments on morphological and physical properties of the hornbeam wood-styrene composite. Test samples were divided according to ASTM D4446-05 to control and treated with MAN, ST, MAN/ST and MAN /ST/GMA. Treatment was performed by vacuum- pressure method using a experimental cylinder. The presence of styrene in the cell cavities, swelling of treated wood with MAN and interaction between MAN/ST and MAN/ST/GMA with wood cell wall were confirmed by Scanning electron microscopy. According to the results, density and weight of the specimens were increased as 73.47 and 79.91; and 5.95 and 11.9% by addition of MAN and MAN/GMA, respectively. Strong interactions between wood structure and combination of MAN/ST/GMA led toan improvement in the compatibility of polymer with cell wall and reduction in porosity of the treated wood. hydrophobicity and dimensional stability of wood polymer composites were improved as the result of modification with MAN and impregnation with ST, so that after the longest immersion time, water absorption and dimensional changes in MAN/ST/GMA with 42/44% weight percent gain, decreased up to 57/78 and 50.15% in comparison with the untreated samples. The highest anti-swelling efficiency was determined in MAN/ST/GMA treatment.

To investigate the variation between and within same populations of Diospyros lotus based on fruit morphological characteristics، five populations (A، B، C، D، E) were selected along two altitude transects (populations A، B and C with a height of 300، 500 and 700 meters from the sea level، respectively in eastern Band pey forests of Babol and populations D and E with an elevation of 300 and 500 meters in Shastklateh، Gorgan). From each site 10 genotypes were randomly selected and some fruits of each genotype was collected in mid-October. After mixing the fruits، five fruits with three replicates were randomly separated and totally five traits measured. The results indicated that the difference between the populations for all traits was significant (p≤ 0. 01). The mean comparison between populations also showed that in general، population A has the highest amount of trait mean. The analysis of variances within population also indicated that except population A، in other populations for all studied traits، there was significant difference between genotypes. Based on the results of this study، this species has high morphological diversity in fruit characteristics among and within studies populations and the best genotypes in order to gather fruit، were 5 and 6 from population A، 2 and 6 from population B، 3، 4 and 5 from population C، 4 and 5 from D and 5 and 4 from population E.

The aim of study was to evaluate qualitative and quantitative characteristics of old trees in Pattom and Namkhaneh districts in the Nowshahr, Northern Iran. The trees quantitative characteristics of DBH, total height, slenderness coefficient, trunk height, crown length, buttress height, and canopy cover area and qualitative characteristics of crown and trunk, i.e., health, vitality, and concurrent, decay, health, branching system, form, and quality were measured. DBH was regarded as a criterion for identification of old trees, hence, the minimum DBH was considered for each species. Non-plot method was used in the regions with slopes lower than 60%. Full forest inspection showed 49 individual old trees composed of eight tree species. Quercus castaneifolia had the absolute maximum and maximum average of DBH, as well as the maximum height. The mean values of the slenderness coefficient, trunk relative height, crown relative length, buttress relative height, and canopy cover area were 20.2, 42.7%, 57.3%, 4.4%, and 325 m2, respectively. The mean values of the healthy crown, good condition of crown vitality, in-concurrent of crown, trunk without any decay, and cavity of trunk averaged 88%, 59%, 39%, 45%, 59, respectively. Forty five percent of old trees had no single trunk and two-third of them was categorized as middle and poor classes. This research was the first of its kind to address and introduce old trees in the natural Hyrcanyan forests of northern Iran.

Identifying the best attributes of seedlings for evaluation of quality of them has an important role in successful reforestation projects. In this study, some morphological characteristics were used for evaluation of quality of oak seedlings. Seedlings were sampled by method of systematic-random from the planting bed in nursery in late February. Statistical analyses were done after measurement of morphological characteristics. Results of correlation analysis showed that the root collar diameter (RCD) had the strongest correlation with other morphological characteristics. Parameters of leaf area, root volume, number of first order lateral roots, stem height, and length of the main root, respectively, had lower correlations with others, then had less important in seedling quality evaluation. Therefore, in according to this study the RCD is the best characteristic for seedlings quality evaluation of this species in nursery.

Morphological characteristics are important variables applied in forest inventory practices. This paper investigates such variables as diameter at breast height, basal area, height, crown length and width, volume, trunk length and ratio and slenderness coefficient as well as stem branching behavior on 289 stems in a pure stand and 259 stems in a mixed stand with uneven-aged structure in Gorazbon district, North of Iran. Results show no difference between two stands except for height and trunk length which is significantly higher for pure stand while there is no significant difference (α= 0.05) for all concerned variable for beech trees between the two stands.